MAGNETIC METALLOMESOGENIC COMPLEXES OF Cu(II), Ni(II), Co(II), AND Mn(II) WITH CYCLAM AND SUBSTITUTED ARYLCARBOXYLATES NAIMA SHARMIN

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1 MAGNETIC METALLOMESOGENIC COMPLEXES OF Cu(II), Ni(II), Co(II), AND Mn(II) WITH CYCLAM AND SUBSTITUTED ARYLCARBOXYLATES NAIMA SHARMIN THESIS SUBMITTED IN FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY FACULTY OF SCIENCE UNIVERSITY OF MALAYA KUALA LUMPUR 2016

2 UNIVERSITY OF MALAYA ORIGINAL LITERARY WORK DECLARATION Name of Candidate: Naima Sharmin (I.C/Passport No: BJ ) Registration/Matric No: SHC Name of Degree: DOCTOR OF PHILOSOPHY Title of Project Paper/Research Report/Dissertation/Thesis ( this Work ): MAGNETIC METALLOMESOGENIC COMPLEXES OF Cu(II), Ni(II), Co(II) AND Mn(II) WITH CYCLAM AND SUBSTITUTED ARYLCARBOXYLATES Field of Study: INORGANIC CHEMISTRY I do solemnly and sincerely declare that: (1) I am the sole author/writer of this Work; (2) This Work is original; (3) Any use of any work in which copyright exists was done by way of fair dealing and for permitted purposes and any excerpt or extract from, or reference to or reproduction of any copyright work has been disclosed expressly and sufficiently and the title of the Work and its authorship have been acknowledged in this Work; (4) I do not have any actual knowledge nor do I ought reasonably to know that the making of this work constitutes an infringement of any copyright work; (5) I hereby assign all and every rights in the copyright to this Work to the University of Malaya ( UM ), who henceforth shall be owner of the copyright in this Work and that any reproduction or use in any form or by any means whatsoever is prohibited without the written consent of UM having been first had and obtained; (6) I am fully aware that if in the course of making this Work I have infringed any copyright whether intentionally or otherwise, I may be subject to legal action or any other action as may be determined by UM. Candidate s Signature Date: Subscribed and solemnly declared before, Witness s Signature Date: Name: Dr. Norbani Abdullah Designation:

3 ABSTRACT The objectives of this research were to synthesise and characterize metal(ii) complexes with 1,4,8,11-tetraazacyclotetradecane (cyclam) and substituted arylcarboxylates, and to study their magnetic and mesogenic properties. The ligands were 4-CH 3 (CH 2 ) 15 OC 5 H 5 N, 4-CH 3 (CH 2 ) n OC 6 H 4 COO - (n = 9, 11, 13, 15) and cyclam. To form metallomesogenic complexes, the mononuclear Cu(II)-cyclam complexes of 4-XC 6 H 4 COO - (X = F, Cl, Br, I, NO 2 ) obtained were reacted with 4-hexadecyloxypyridine. Finally, the dinuclear M(II) complexes of 4-CH 3 (CH 2 ) n OC 6 H 4 COO - (M = Cu(II), Ni(II), Co(II) and Mn(II); n = 9, 11, 13, 15) were reacted with cyclam to form stable mononuclear magnetic metallomesogenic complexes. A total of 21 complexes were synthesized and their structural formulae were deduced either by single crystal XRD (for crystals) or by combined instrumental data from elemental analyses, FTIR spectroscopy and UV-vis spectroscopy. Their magnetic properties were determined as room-temperature magnetic susceptibility by the Gouy method, and their thermal and mesomorphic properties were studied by thermogravimetry (TGA), differential scanning calorimetry (DSC), and polarizing optical microscopy (POM). The organic ligands were also characterized by 1 H-NMR spectroscopy. All complexes have octahedral M(II) centres, paramagnetic and thermally stable. The thermal stabilities of [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (T dec = C) were lower than [Cu(cyclam)(H 2 O) 2 ](R) 2, [M(cyclam)(R) 2 ].2H 2 O, and [Mn(cyclam)(R) 2 ]R.2H 2 O (M = Ni, Co; R = 4-CH 3 (CH 2 ) n OC 6 H 4 COO; n = 9, 11, 13, 15; T dec = C). All complexes, except for [Cu(cyclam)(L) 2 ] (4-NO 2 C 6 H 4 COO) 2.2H 2 O, exhibited mesomorphism. iii

4 ABSTRAK Objektif penyelidikan ini adalah untuk mensintesis dan menciri kompleks logam(ii) dengan 1,4,8,11-tetraazasiklotetradekana (siklam) dan arilkarboksilat tertukarganti, dan mengkaji sifat magnet dan mesogen kompleks yang disediakan. Ligan adalah 4-CH 3 (CH 2 ) 15 OC 5 H 5 N, 4-CH 3 (CH 2 ) n OC 6 H 4 COO - (n = 9, 11, 13, 15) and dan siklam. Untuk membentuk kompleks metalomesogenik, kompleks mononukleus Cu(II)-siklam dengan 4-XC 6 H 4 COO - (X = F, Cl, Br, I, NO 2 ) yang diperoleh ditindakbalaskan dengan 4-heksadesiloksipiridina. Akhir sekali, kompleks dinuklear M(II) dengan 4-CH 3 (CH 2 ) n OC 6 H 4 COO - (M = Cu(II), Ni(II), Co(II) dan Mn(II); n = 9, 11, 13, 15) ditindakbalaskan dengan siklam untuk membentuk kompleks magnetic metalomesogenik mononukleus yang stabil. Sejumlah 21 kompleks disintesiskan dan formula struktur kompleks-kompleks ini dideduksi sama ada melalui XRD hablur tunggal (untuk hablur) atau melalui gabungan data alatan dari analisis unsur, spektroskopi FTIR dan spektroskopi UVnampak. Sifat magnet kompleks ditentukan melalui kerentanan magnet suhu bilik menggunakan kaedah Gouy, dan sifat terma dan mesomorfik dikaji melalui termogravimetri (TGA), kalorimetri imbasan pembeza (DSC), dan mikroskopi pengutuban optik (POM). Ligan organik juga dicirikan melalui spektroskopi 1 H-NMR. Semua kompleks mempunyai pusat M(II) oktahedron, paramagnetik dan stabil secara terma. Kestabilan terma [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (T dec = C) adalah lebih rendah berbanding [Cu(cyclam)(H 2 O) 2 ](R) 2, [M(cyclam)(R) 2 ].2H 2 O dan [Mn(cyclam)(R) 2 ]R.2H 2 O (M = Ni, Co; R = 4-CH 3 (CH 2 ) n OC 6 H 4 COO; n = 9, 11, 13, 15; T dec = C). Semua kompleks, kecuali [Cu(cyclam)(L) 2 ] (4-NO 2 C 6 H 4 COO) 2.2H 2 O, menunjukkan mesomorfisme. iv

5 DEDICATED TO My Parents Husband & Dr. Norbani Abdullah v

6 ACKNOWLEDGEMENTS First of all, I want to convey my cordial gratitude to ALLAH for bestowing his great mercy to me. This research is the product of dynamic and challenging collegial relationships, unflagging friendships, and endless patience on the part of a very special group of individuals. Foremost, I would like to express my sincere acknowledgement to my incredible doctoral adviser Assoc. Prof. Dr. Norbani Abdullah for her intellectual mentorship and emotional guidance throughout this process. I was truly lucky that she has opened the door to opportunities that I never would have imagined, and has supported and encouraged me throughout my PhD studies. I have always been able to turn to her for advice, feedback, motivation and help, both in the context of my research and life in general. The project was financially supported by University of Malaya research grants; FP008/2011A, PV056/2012A and UM.C/625/1/HIR/MOHE/CHAN/05. I particularly thank my husband, Ferdous Ahmed, for his amazing love, support, encouragement, and patience. Also my thanks to my beloved parents and sisters for their unconditional love throughout my life. A special word of thanks also goes to my friends and colleagues over the years who have made my time in University of Malaya so enjoyable. In addition, many thanks to all the staffs in Department of Chemistry, University of Malaya. vi

7 TABLE OF CONTENTS ABSTRACT ACKNOWLEDGEMENTS LIST OF FIGURES LIST OF TABLES LIST OF SCHEMES iii vi xii xxviii xxxi CHAPTER 1: INTRODUCTION Objectives and methodology Thesis 2 CHAPTER 2: THEORY AND LITERATURE REVIEW Copper(II) arylcarboxylates Structures and properties Copper carboxylate-cyclam complexes Dinuclear copper carboxylate metallomesogens Mononuclear copper carboxylate-cyclam metallomesogens Nickel arylcarboxylates Structures and properties Nickel carboxylate-cyclam complexes Dinuclear nickel carboxylate metallomesogens Mononuclear nickel carboxylate-cyclam metallomesogens Cobalt arylcarboxylates Structures and properties Dinuclear cobalt carboxylate metallomesogens Mononuclear cobalt carboxylate cyclam metallomesogens 44 vii

8 2.10 Manganese carboxylates Structures and properties Manganese Carboxylate-Cyclam Complexes Dinuclear manganese carboxylate metallomesogens Mononuclear manganese carboxylate-cyclam metallomesogens Introduction Materials [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO) 2 (X = F, Cl, Br, I, and NO 2 ) Synthesis of 4-hexadecyloxypyridine (L) [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] [M(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2.2H 2 O; (M = Cu(II), Ni(II), Co(II), and Mn(II); n = 9, 11, 13 and 15) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (6) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2.2H 2 O (7) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 2H 2 O (8) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O (9) [Ni(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (10) [Ni(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (11) [Ni(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O (12) [Ni(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O (13) [Co(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (14) [Co(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (15) 60 viii

9 [Co(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O (16) [Co(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O (17) [Mn(cyclam)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Instrumental Analyses H-Nuclear magnetic resonance spectroscopy Elemental analyses X-ray crystallography Fourier transform infrared spectroscopy UV-visible spectroscopy Magnetic susceptibility Thermogravimetry Differential scanning calorimetry Polarizing optical microscopy 64 CHAPTER 4: RESULTS AND DISCUSSION Introduction [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO) [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2 2H 2 O [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) Concluding remarks [Cu(cyclam)(H 2 O) 2 ](4-ROC 6 H 4 COO) ix

10 4.4.1 [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 2H 2 O [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2.2H 2 O [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2.2H 2 O [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O Concluding remarks [Ni(cyclam)(4-ROC 6 H 4 COO) 2 ].2H 2 O [Ni(cyclam(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 )].2H 2 O [Ni(cyclam(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 )].2H 2 O [Ni(cyclam(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 )].2H 2 O [Ni(cyclam(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 )].2H 2 O Concluding remarks [Co(cyclam)(4-ROC 6 H 4 COO) 2 ].2H 2 O [Co(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 )].2H 2 O [Co(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 )].2H 2 O [Co(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 )].2H 2 O [Co(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 )].2H 2 O Concluding Remarks [Mn(cyclam)(4-ROC 6 H 4 COO) 2 ](4-ROC 6 H 4 COO).2H 2 O [Mn(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ] (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO).2H 2 O [Mn(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ] (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO).2H 2 O [Mn(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ] (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO).2H 2 O [Mn(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ] (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO).2H 2 O Concluding Remarks 253 x

11 CHAPTER 5. CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORKS Conclusions Suggestions for Future Works 255 References 257 APPENDICES xi

12 LIST OF FIGURES Figure 2.1 Paddle-wheel structure of dimeric copper(ii) benzoate [71] 5 Figure 2.2 Crystal structure of [Cu 2 (C 6 H 5 COO) 4 (DMSO) 2 ] [76] 5 Figure 2.3 Crystal structure of [Cu 2 (4-FC 6 H 4 COO) 4 (C 2 H 5 OH) 2 ] [77] 6 Figure 2.4 ORTEP view of [Cu 2 (4-ClC 6 H 4 COO) 4 (isopropanol) 2 ] [88] 8 Figure 2.5 Crystal structure of [Cu 2 (µ-o 2 CC 6 H 4 OH) 4 (C 7 H 7 NO) 2 ].6H 2 O [96] 9 Figure 2.6 Figure 2.7 Figure 2.8 Figure 2.9 Figure 2.10 Figure 2.11 Molecular structure of tetrakis(μ-4-nit-benzoato)dicopper(ii) [102] Molecular structure of tetrakis(diphenylacetato-μ-o, O ) bis(acetone-o)dicopper(ii) [104] A column of the hydrogen-bonded components of trans- [Cu(H 2 O 2 )(cyclam)](c 6 H 5 COO) 2.2H 2 O [111] A column of the hydrogen-bonded components of trans- [Cu(H 2 O) 2 (cyclam)](4-t-butyl-benzoate) 2 [111] Crystal structure of [Cu(cyclam)(H 2 O) 2 ](4-CH 3 C 6 H 4 COO) 2.2H 2 O [112] Crystal structure of [Cu(C 10 H 24 N 4 )(H 2 O) 2 ](C 6 F 5 -CO 2 ) 2.2H 2 O [113] Figure 2.12 Discotic mesophase of a copper(ii) carboxylate [138] 18 Figure 2.13 Rhodium(II) 4-alkyloxybenzoates [140] 19 Figure 2.14 Figure 2.15 Figure 2.16 Figure 2.17 DSC thermogram of the first heating and cooling processes for [Rh 2 (μ-oocc 6 H 4-4-OC 10 H 21 ) 4 ]. An asterisk indicates the peak due to the endothermic loss of small amounts of coordinated water [140] The mesophase of [Rh 2 (μ-oocc 6 H 4-4-OC 11 H 23 ) 4 ] viewed under crossed polarizers [140] Metallomesogenic tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclo hexadecane (M = 2H; n = 8, 10, 12 [127]; M = Cu; n = 10, 12, 14, 16, 18 [149]) Texture of tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane viewed under a polarizing microscope at 70 C [152] xii

13 Figure 2.18 Photomicrograph of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2 at C, on cooling from the isotropic liquid phase [153] 24 Figure 2.19 Crystal structure of [Ni 2 (μ-h 2 O)(μ-PhCOO) 2 (PhCOO) 4 (C 5 H 5 N) 4 ].1.5C 6 H 6 [155] 25 Figure 2.20 Crystal structure of [Ni 2 (H 2 O)(2-NO 2 PhCOO) 4 (Py) 4 ] [155] 26 Figure 2.21 Crystal structure of [Ni 2 (H 2 O)Cl(4-ClC 6 H 4 COO) 3 (py) 4 ] [155] 27 Figure 2.22 Ball-stick diagram of the coordination arrangement around the Ni centers for [Ni 2 (L) 2 (py) 4 (H 2 O)] n [157] 28 Figure 2.23 Plot of χm and χ M -1 vs T for [Ni 2 (L) 2 (py) 4 (H 2 O)] n [157] 28 Figure 2.24 Projection of the centrosymmetric molecule of trans- [Ni(O-benzoato) 2 (cyclam)] [111] 31 Figure 2.25 Molecular structure of [Ni(cyclam)(H 2 O) 2 ](fumarate).4h 2 O [178] 32 Figure 2.26 Ni(II) complex of tetrabenzo[b,f,j,n][1,5,9,13] tetraazacyclohexadecane (n = 10,12,14,16,18) [149] 32 Figure 2.27 Structural types of dinuclear cobalt(ii) carboxylates [183] 35 Figure 2.28 Crystal structure of [Co 2 (μ-h 2 O)(μ-Bz) 2 (Bz) 2 (py) 4 ](C 6 H 6 )(BzH) [187] 36 Figure 2.29 Crystal structure of [Co 2 (μ-h 2 O)(μ-p-ClBz) 2 (p-clbz)(py)] [187] 37 Figure 2.30 Crystal structure of [Co 2 (µ-oh 2 )(C 5 H 5 N) 4 (µ-r) 2 R] (R = 2-NO 2 OOCC 6 H 4 ) [193] 38 Figure 2.31 Molecular structure of [(μ 2 -H 2 O)(μ 2 -PhCOO) 2 {Co(PhCOO-κ 1 -O) (Mepy) 2 } 2 ] [183] 39 Figure 2.32 (a) electronic spectrum; and (b) term diagram of [(μ 2 -H 2 O) (μ 2 -PhCOO) 2 {Co(PhCOO-κ 1 -O)(Mepy) 2 } 2 ] [183] 40 Figure 2.33 Different configurations of cobalt-cyclam complexes [195] 41 Figure 2.34 Molecular structure of [CoCl 2 (C 10 H 24 N 4 )]Cl.4H 2 O.0.47HCl [196] 41 Figure 2.35 Figure 2.36 Infrared spectra of some cobalt(iii) complexes showing difference between cis- and trans-isomer [201] Cobalt complex of 5,10,15,20-tetrakis(decyloxyphenyl)porphyrin; R = OC 10 H 21 [209] xiii

14 Figure 2.37 Figure 2.38 Carboxylate binding modes involved in dinuclear Mn(II) compounds with two carboxylate bridges Drawing of the cation [Mn 2 (µ-phcoo) 2 (bpy) 4 ] 2+ showing the syn-anti conformation of the carboxylate bridges [246] Figure 2.39 Crystal structures of the cationic complex of [{Mn(phen) 2 } 2 (m-clc 6 H 4 COO) 2 ](ClO 4 ) 2 [211] 47 Figure 2.40 π-stacking between phen ligands of dinuclear units of [{Mn(phen) 2 } 2 (m-clc 6 H 4 COO) 2 ](ClO 4 ) 2 generating chains [211] 48 Figure 2.41 χ M T vs T and χ M vs T (inset) plots for [{Mn(phen) 2 } 2 (m-clc 6 H 4 COO) 2 ](ClO 4 ) 2 ( ). The solid line is the best fit to the experimental data [211] 49 Figure 2.42 One oxo and two acetate bridged manganese complex [259] 49 Figure 2.43 Plots of χ M -l and μ eff vs T of [Mn 2 (µ-o)(µ-mecoo) 2 {HB(pz) 3 } 2 ] [259] 50 Figure 2.44 ORTEP drawing of [Mn 2 (H 2 O)(Piv) 4 (Me 2 Bpy) 2 [262] 51 Figure 2.45 Figure 3.1 Manganese complex of 5,10,15,20-tetrakis(4-n-dodecylphenyl) porphyrin; R = C 12 H 25 ; X = Cl -, TCNQ - (tetracyanoquinodimethane) [270] The structural formula of the ligands: (a) 4-n-alkyloxybenzoate ion (n = 9, 11, 13, and 15); (b) 1,4,8,11-tetraazacyclotetradecane (cyclam); and (c) 4-hexadecyloxypyridine (L) Figure H-NMR spectrum of 4-hexadecyloxypyridine (L) 66 Figure 4.2 IR spectrum of 4-hexadecyloxypyridine (L) 66 Figure 4.3 (a) Molecular view of [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O showing displacement ellipsoids at 50% probability level, (b) supramolecular chain; most of the alkyl chains and all nonacidic hydrogen atoms have been removed for clarity. The O H O and N H O hydrogen bonds, shown as blue and green dashed lines respectively, lead to a chain. Colour code: Cu, light blue; O, red; N, blue; C, grey; and F, green 69 Figure 4.4 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O 70 Figure 4.5 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O 71 Figure 4.6 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) 72 xiv

15 Figure 4.7 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) 72 Figure 4.8 Proposed structure of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) (R = C 16 H 33 ); lattice H 2 O is not shown 73 Figure 4.9 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O 74 Figure 4.10 TGA trace for [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) 75 Figure 4.11 DSC scans of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) 76 Figure 4.12 Photomicrographs (on cooling) of [Cu(cyclam)(L) 2 ] (4-FC 6 H 4 COO) 2.2H 2 O (1) at: (a) 84.4 C and (b) 73.8 C 76 Figure 4.13 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O 77 Figure 4.14 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O 78 Figure 4.15 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) 79 Figure 4.16 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) 80 Figure 4.17 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O 81 Figure 4.18 TGA trace for [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) 81 Figure 4.19 DSC scans of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) 82 Figure 4.20 Photomicrographs (on cooling) of [Cu(cyclam)(L) 2 ] (4-ClC 6 H 4 COO) 2.2H 2 O (2) at: (a) 100 C and (b) 84 C 83 Figure 4.21 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O 84 Figure 4.22 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O 85 Figure 4.23 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) 86 Figure 4.24 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) 86 Figure 4.25 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O 87 Figure 4.26 TGA trace for [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) 88 Figure 4.27 DSC scans of [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) 89 Figure 4.28 Photomicrograph (on cooling) of [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (3) (R = 4-BrC 6 H 4 COO) at 77.3 C 89 Figure 4.29 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2 2H 2 O 90 xv

16 Figure 4.30 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2 2H 2 O 91 Figure 4.31 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) 92 Figure 4.32 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) 93 Figure 4.33 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2.2H 2 O 94 Figure 4.34 TGA trace for [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) 95 Figure 4.35 DSC scans of [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) 96 Figure 4.36 Photomicrograph (on cooling) of [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (4) (R = 4-IC 6 H 4 COO) at 71.9 C Figure 4.37 (a) Molecular view, showing displacement ellipsoids at 50% probability level and (b) supramolecular chain for [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O; most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity. The O H O and N H O hydrogen bond shown as blue and green dashed lines respectively, lead to a chain. Colour code: Cu, light blue; O, red; N, blue; and C, grey Figure 4.38 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O 99 Figure 4.39 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O 100 Figure 4.40 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) 101 Figure 4.41 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) 101 Figure 4.42 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O 102 Figure 4.43 TGA trace for [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) 103 Figure 4.44 DSC scans of [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) 104 Figure 4.45 (a) Molecular view, showing displacement ellipsoids at 50% probability level and (b) Supramolecular association operating in the crystal structure of [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ]. The intermolecular N H O hydrogen bonding (green dashed lines) leads to a two-dimensional array.intramolecular N H...O-N hydrogen bonds are shown as blue dashed lines.colour code: Same as in Figure Figure 4.46 FTIR spectrum of [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] 107 Figure 4.47 UV-vis spectrum of [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] 107 xvi

17 Figure 4.48 TGA trace for [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] 108 Figure H-NMR spectrum of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H Figure 4.50 FTIR spectrum of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H Figure 4.51 FTIR spectrum of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK 113 Figure 4.52 Structure of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK 113 Figure 4.53 FTIR spectrum of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 114 Figure 4.54 UV-vis spectrum of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 114 Figure 4.55 Figure 4.56 Schematic representation of the proposed structure of [Cu 2 (4-ROC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (R = CH 3 (CH 2 ) 9 ); lattice water are not shown (a) Molecular view of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6), showing displacement ellipsoids at 50% probability level; R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO; operator used to generate symmetry equivalent elements: -x, -y+2, -z+1; (b) supramolecular chain; most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity. The O H O and N H O hydrogen bond shown as blue and green dashed lines respectively, lead to a chain. Colour code: Same as in Figure Figure 4.57 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure 4.58 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure 4.59 TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 120 Figure 4.60 TGA trace for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 121 Figure 4.61 DSC scans of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 122 Figure 4.62 Photomicrographs (on cooling) of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O at: (a) 135 C and (b) 92 C Figure 4.63 DSC scans of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) xvii

18 Figure 4.64 Photomicrographs (on cooling) of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) at: (a) o C, (b) o C, and (c) o C (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 124 Figure H-NMR spectrum of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H Figure 4.66 IR spectrum of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H Figure 4.67 IR spectrum of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOK 127 Figure 4.68 FTIR spectrum of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 128 Figure 4.69 UV-vis spectrum of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 128 Figure 4.70 (a) Molecular view of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) showing displacement ellipsoids at 70% probability level (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO); operator used to generate symmetry equivalent elements: -x+2, -y+2, -z;. (b) supramolecular chain along [1-1 0]; all non-acidic hydrogen atoms have been removed for clarity. The O H O and N H O hydrogen bond shown as blue and green dashed lines respectively, lead to a chain. Colour code: Same as in Figure Figure 4.71 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure 4.72 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure 4.73 TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 133 Figure 4.74 TGA trace for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 134 Figure 4.75 DSC scans of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 135 Figure 4.76 Photomicrographs (on cooling) of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O at: (a) 120 o C, and (b) 118 o C 135 Figure 4.77 DSC scans of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 136 Figure 4.78 Photomicrograph (on cooling) of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) at 135 o C (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 137 Figure H-NMR spectrum of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H xviii

19 Figure 4.80 IR spectrum of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H Figure 4.81 IR spectrum of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOK 140 Figure 4.82 FTIR spectrum of [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 140 Figure 4.83 UV-vis spectrum of [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Figure 4.84 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure 4.85 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure 4.86 TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 143 Figure 4.87 TGA trace for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 144 Figure 4.88 DSC scans of [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 145 Figure 4.89 Photomicrograph (on cooling) of [Cu 2 (R) 4 (H 2 O) 2 ].2H 2 O at C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 145 Figure 4.90 DSC scans of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure 4.91 Photomicrograph of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) on cooling at o C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure H-NMR spectrum of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H Figure 4.93 FTIR spectrum of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H Figure 4.94 FTIR spectrum of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOK 149 Figure 4.95 Figure 4.96 FTIR spectrum of [Cu 2 (R) 4 (H 2 O) 2 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) UV-vis spectrum of [Cu 2 (R) 4 (H 2 O) 2 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) xix

20 Figure 4.97 (a) Molecular view showing O H...O and N H...O hydrogen bonds between the components of the asymmetric unit of [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O (9) and (b) supramolecular chain along [1-1 0]; most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity, and (c) a view in projection down the b-axis of the unit cell contents. The O H O and N H O hydrogen bond shown as orange and blue dashed lines respectively, lead to a chain. Colour code Cu, orange; O, red; N, blue; C, grey; and H, green 152 Figure 4.98 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure 4.99 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 155 Figure TGA trace for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 156 Figure DSC scans of [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 157 Figure Photomicrographs (on cooling) of [Cu 2 (R) 4 (H 2 O) 2 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO at: (a) C; and (b) 83.0 o C Figure DSC scans of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure Photomicrographs (on cooling) of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) at: (a) 141 C; and (b) 89.9 C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure FTIR spectrum of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 160 Figure UV-vis spectrum of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 161 Figure Schematic representation of the proposed structure of [Ni 2 (RCOO) 4 (H 2 O) 5 ] (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 ) Figure (a) Molecular view, showing displacement ellipsoids at 50% probability level; and (b) packing diagram of [Ni(cyclam) (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (10); operator used to generate symmetry equivalent elements: -x+1, -y+1, -z. Colour code: Ni, green; O, red; N, blue; and C, grey xx

21 Figure FTIR spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure UV-vis spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure TGA trace for [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 166 Figure TGA trace for [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 166 Figure DSC scans of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 167 Figure DSC scans of [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure Photomicrograph of [Ni(cyclam)(R) 2 ].2H 2 O (10) on cooling at 100 o C (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure FTIR spectrum of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 169 Figure UV-vis spectrum of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 170 Figure (a) Molecular view, showing displacement ellipsoids at 50% probability level; (b) packing diagram of [Ni(cyclam) (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (11) along crystallographic b-axis; operator used to generate symmetry equivalent elements: -x+1, -y+1, -z. Colour code: same as in Figure Figure FTIR spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure UV-vis spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure TGA trace for [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 174 Figure TGA trace for [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 175 Figure DSC scans of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 175 Figure DSC scans of [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure Photomicrographs of [Ni(cyclam)(R) 2 ].2H 2 O (11) on cooling at: (a) o C; and (b) 51.3 o C (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) xxi

22 Figure FTIR spectrum of [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O 177 Figure UV- vis spectrum of [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure FTIR spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure UV-vis spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure TGA trace for [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O 181 Figure TGA trace for [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 181 Figure DSC scans of [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] 182 Figure Photomicrographs (on cooling) of [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O at: (a) o C, and (b)129.8 o C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure DSC scans of [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure Photomicrographs (on cooling) of [Ni(cyclam)(R) 2 ].2H 2 O (12) at 47.7 o C: (a) initial time; and (b) after 3 min (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure FTIR spectrum of [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O 185 Figure UV-vis spectrum of [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure FTIR spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure UV-vis spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure TGA trace for [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ] 188 Figure TGA trace for [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 189 Figure DSC scans of [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ] 190 xxii

23 Figure DSC scans of [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure Photomicrograph (on cooling) of [Ni(cyclam)(R) 2 ].2H 2 O (13) at 88.6 o C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure FTIR spectrum of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 192 Figure UV-vis spectrum of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 193 Figure Schematic representation of the proposed structure of [Co 2 (4-RCOO) 4 (H 2 O) 5 ] (R = CH 3 (CH 2 ) 9 OC 6 H 4 ) Figure FTIR spectrum of [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure UV-vis spectrum of [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure Proposed structure of [Co(cyclam)(4-ROC 6 H 4 COO) 2 ].2H 2 O (14) (R = CH 3 (CH 2 ) 9 ); lattice H 2 O are not shown Figure TGA trace for [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 196 Figure TGA trace for [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 197 Figure DSC scans of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 197 Figure DSC scans of [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure Photomicrographs (on cooling) of [Co(cyclam)(R) 2 ].2H 2 O (14) at: (a) o C; and (b) 97.3 o C (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure FTIR spectrum of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 199 Figure UV-vis spectrum of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 200 Figure FTIR spectrum of [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure UV-vis spectrum of [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure TGA trace for [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 203 xxiii

24 Figure TGA trace for [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 203 Figure DSC scans of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 204 Figure DSC scans of [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure Photomicrographs (on cooling) of [Co(cyclam)(R) 2 ].2H 2 O (15) at: (a) 91 o C; and (b) 65.7 o C (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure FTIR spectrum of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] 206 Figure UV-vis spectrum of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] 207 Figure FTIR spectrum of [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure UV-vis spectrum of [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure TGA trace for [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] 210 Figure TGA trace for [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 210 Figure DSC scans of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] 211 Figure DSC scans of [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure Photomicrographs (on cooling) of [Co(cyclam)(R) 2 ].2H 2 O (16) at: (a) 56.7 o C; and (b) 45.7 o C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure FTIR spectrum of [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure UV-vis spectrum of [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure FTIR spectrum of [Co(cyclam)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) xxiv

25 Figure UV-vis spectrum of [Co(cyclam)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 216 Figure TGA trace for [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O 217 Figure TGA trace for [Co(cyclam)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 217 Figure DSC scans of [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O 218 Figure Photomicrograph (on cooling) of [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O at o C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure DSC scans of [Co(cyclam)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure Photomicrographs (on cooling) of [Co(cyclam)(R) 2 ].2H 2 O (17) at: (a) o C; and (b) o C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 221 Figure Schematic representation of the proposed structure of [Mn 2 (4-ROC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (R = CH 3 (CH 2 ) 9 ); lattice H 2 O are not shown 222 Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 223 Figure UV-vis spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure Proposed structure of [Mn(cyclam)(4-ROC 6 H 4 COO) 2 ] (4-ROC 6 H 4 COO).2H 2 O (18) (R = CH 3 (CH 2 ) 9 ); lattice H 2 O are not shown Figure TGA trace for [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 225 Figure TGA trace for [Mn(cyclam)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 226 Figure DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 227 Figure DSC scans of [Mn(cyclam)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure Photomicrographs of [Mn(cyclam)(R) 2 ]R.2H 2 O (18) on cooling at: (a) 88.1 o C; and (b) 71.3 o C (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 229 xxv

26 Figure (a) Molecular view, showing displacement ellipsoids at 50% probability level; and (b) supramolecular chain of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity. O-H O and N-H O hydrogen bonds are shown in blue and green dashed lines respectively. Colour code: Mn, purple; O, red; N, blue; and C, grey Figure FTIR spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure UV-vis spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure TGA trace for [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 234 Figure TGA trace for [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 235 Figure DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 236 Figure DSC scans of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure Photomicrographs of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) on cooling at: (a) 90.1 o C; and (b) 56.7 o C (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] 238 Figure (a) Molecular view, showing displacement ellipsoids at 50% probability level; and (b) packing diagram of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO). Colour code: same as in Figure Figure FTIR spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure UV-vis spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure TGA trace for [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] 243 Figure TGA trace for [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 244 Figure DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] 245 xxvi

27 Figure DSC scans of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure Photomicrographs (on cooling) of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) at: (a) 82.9 o C; and (b) 43.4 o C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 247 Figure FTIR spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure UV-vis spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure TGA trace for [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 250 Figure TGA trace for [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 250 Figure DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 251 Figure DSC scans of [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure Photomicrographs (on cooling) of [Mn(cyclam)(R) 2 ]R.2H 2 O (21) at: (a) 90.8 o C; (b) 88.9 o C; and (c) 38.7 o C(R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Figure 5.1 (a) A platinated discotic metallomesogen, and (b) its optical texture at 120 C (Col h phase) [337] 256 xxvii

28 LIST OF TABLES Table 2.1 Table 2.2 Table 2.3 The Thermotropic behavior of Cu(II) complexes of tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane [149] Relative strain energies (kcal mol -1 ) for planar and octahedral conformers of Ni(II) cyclam complexes [162] Thermotropic behavior of Ni(II) complexes of tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane [149] Table 3.1 The chemicals used in this research, arranged in alphabetical order 54 Table 4.1 Table 4.2 Table 4.3 Table 4.4 Table 4.5 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (R = 4-FC 6 H 4 COO) [Å and ] FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (1) (R = 4-FC 6 H 4 COO) FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (2) (R = 4-ClC 6 H 4 COO) FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (3) (R = 4-BrC 6 H 4 COO) FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (4) (R = 4-IC 6 H 4 COO) Table 4.6 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ] (4-NO 2 C 6 H 4 COO) 2.2H 2 O [Å and ] 98 Table 4.7 FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (5) (R = 4-NO 2 C 6 H 4 COO) 99 Table 4.8 Selected Hydrogen bonds for [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] [Å and ] 105 Table 4.9 FTIR data and assignments of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H 5 and its corresponding metal complexes 112 Table 4.10 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) [Å and ] Table 4.11 FTIR data and assignments of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H 5 and its corresponding metal complexes Table 4.12 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Å and ] xxviii

29 Table 4.13 FTIR data and assignments of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H 5 and its corresponding metal complexes Table 4.14 FTIR data and assignments of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H 5 and its corresponding metal complexes Table 4.15 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO [Å and ] Table 4.16 FTIR data and assignments of [Ni 2 (R) 4 (H 2 O) 5 ] and [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Table 4.17 Hydrogen bonds for [Ni(cyclam) (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (10) [Å and ] Table 4.18 FTIR data and assignments of [Ni 2 (R) 4 (H 2 O) 5 ] and [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Table 4.19 Selected Hydrogen bonds for [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Å and ] Table 4.20 FTIR data and assignments of [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O and [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Table 4.21 FTIR data and assignments of [Ni 2 (R) 4 (H 2 O) 5 ] H 2 O and [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Table 4.22 FTIR data and assignments of [Co 2 (R) 4 (H 2 O) 5 ] and [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Table 4.23 FTIR data and assignments of [Co 2 (R) 4 (H 2 O) 5 ] and [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Table 4.24 FTIR data and assignments of [Co 2 (R) 4 (H 2 O) 5 ] and [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Table 4.25 FTIR data and assignments of [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O and [Co(cy)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO, cy = cyclam) Table 4.26 FTIR data and assignments of [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O and [Mn(cy)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO, cy = cyclam) Table 4.27 FTIR data and assignments of [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O and [Mn(cy)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO, cy = cyclam) xxix

30 Table 4.28 Selected Hydrogen bonds for [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Å and ] Table 4.29 FTIR data and assignments of [Mn 2 (R) 4 (H 2 O) 4 ] and [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Table 4.30 Selected Hydrogen bonds for [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) [Å and ] Table 4.31 FTIR data and assignments of [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O and [Mn(cy)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO, cy = cyclam) Table 5.1 Chemical formulae of studied complexes 254 xxx

31 LIST OF SCHEMES Scheme 2.1 (a) dinuclear azopalladium(ii) complex; (b) alkoxy-substituted bis(1,5-diphenyl-1,3,5-pentanetrionato)dicopper(ii) complex; and (c) dinuclear tetraalkanoate-copper(ii) complex; R = long alkyl(oxy) chain 16 Scheme 4.1 Syntheses of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) 67 Scheme 4.2 Synthesis of [Cu(cyclam)(H 2 O) 2 ] (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (6) 110 xxxi

32 CHAPTER 1: INTRODUCTION Magnetic liquid crystals are currently an active research area in metallomesogens (metal-based liquid crystals) [1-6]. In addition, multinuclear metallomesogenic complexes are attractive, as the capability to control the position and orientation of transition metals allow the design of new materials with advantageous magnetic and electronic properties [7-12]. Examples of paramagnetic metal ions are Cu(II) [4, 13, 14], Rh(II), Ru(II), Mo(II), Cr(II) [15] vanadium(ii) [16,17] and lanthanide(iii) ions [18-21]. Other transition metal ions, such as Ni(II), Co(II) and Mn(II), are also promising in this research area. For example, Ni(II) compounds exhibiting cooperative magnetic properties have contributed towards the construction of ferromagnets along with liquidcrystal properties [22]. Another aspect of this research area is introducing a metal ion with spin-crossover properties (SCO). These materials are expected to show novel physical properties originated from the interaction between magnetic and liquid crystal properties toward external stimuli (temperature, pressure, and light). Examples are work done by Hayami et al.[23] on Co(II) complexes exhibiting a unique spin transition induced by phase transitions. Other examples are Mn(III)-tetraphenylporphyrin complexes (Mn[R 4 TPP][TCNE]) containing four long alkyl or alkyloxy chains at the para position of the phenyl rings, which combined ferromagnetic behaviour with liquid crystalline properties [24-26]; these compounds behaved as one-dimensional ferrimagnetic chains in the crystalline phase as well as in the mesophase. Study on several types of mesomorphic macrocyclic structures have shown that these discotic metallomesogens were able to self-assembled in columnar phases due to their molecular shape [27-29]. Such compounds are potential materials in devices based on electronics, photonics, or low dimensional ionic transport [30-36]. Common examples are: (a) tridentate ligands, such as 1,4,7-triazacyclononanes [37]; (b) tetradentate ligands, such as phthalocyanines [38-40], porphyrins [41, 42], tetra- 1

33 azaporphyrins [43], and tetraazacyclotetradecanes [44]; (c) hexadentate ligands, such as hexaazacyclooctadecanes [43]; and (d) octadentate ligands, such as bisphthalocyanines [45, 46]. However, there are only few examples of metallomesogens based on 1,4,8,11- tetraazacyclotetradecane (cyclam) reported in the literature. This N 4 -macrocyclic ligand deserves more attention because of its capability of producing stable complexes with a wide choice of metal ions. 1.1 Objectives and methodology The objectives of this research were to obtain thermally stable metallomesogenic complexes as low-dimensional molecular magnetic materials. Hence, this research project focussed on the syntheses of dinuclear Cu(II), Ni(II), Co(II) and Mn(II) complexes of 4-alkyloxybenzoates followed by their reactions with cyclam. A total of 21 complexes were prepared and fully characterized by elemental analyses, X-ray crystallography (for crystals), FTIR spectroscopy, UV-vis spectroscopy, roomtemperature magnetic susceptibility (Gouy method), thermogravimetry (TGA), differential scanning calorimetry (DSC), and optical polarizing microscopy (POM). 1.2 Thesis This thesis contains five chapters. Chapter 1 presents a brief introduction about the objective of this research, the complexes prepared and the instrumental techniques involved. Chapter 2 presents the theories and literature reviews relevant to the research. Chapter 3 presents the experimental methods used to synthesize the organic ligands and complexes, and the instrumental techniques used to characterize them. Chapter 4 presents the results and discussion of all complexes prepared, and Chapter 5 presents the conclusions and suggestions for future works. A list of references and the appendices were included at the end of the thesis. 2

34 CHAPTER 2: THEORY AND LITERATURE REVIEW 2.1 Copper(II) arylcarboxylates Structures and properties Copper is a first-row transition metal, and its electronic configuration is [Ar]4s 1 3d 10. Hence, its most common ions are copper(i) and copper(ii) ions. Copper(II) ion (valence electronic configuration 3d 9 ) is the most stable ion, paramagnetic, and has a tendency to adopt square planar or distorted octahedral geometries. In the distorted octahedral geometry, four of the ligands frame a square planar geometry while the remaining bonds are extended. Accordingly, the color of most copper(ii) complexes are blue or green. Among copper(ii) compounds, copper(ii) carboxylates have properties of importance in various extents and likewise have been broadly concentrated on [47]. The chemistry of copper(ii) carboxylates keeps on drawing a pronounced deal of attention due to their unique structural, magnetic, catalytic and electrochemical properties, furthermore as potential models for various important biological system containing coupled sites [48-56]. In addition, the flexibility of copper(ii) and carboxylate ligands in their coordination bonding has allowed the synthesis of mononuclear and multinuclear complexes with diverse physico-structural features [57, 58]. Aside from this, binuclear complexes bring about the close proximity of the two central metal ions which right now is the trendy feature for further study in biomimetic inorganic studies [59], in supramolecular chemistry and crystal engineering as well [60-63]. Copper carboxylates are synthesized commonly by the following methods [64-66]: (a) reaction of basic copper (II) carbonate (Cu 2 CO 3 (OH) 2 ) with a carboxylic acid: (b) reaction of sodium salt of the carboxylic acid with copper (II) salt (sulfate, chloride, nitrate); and (c) reaction of copper (II) acetate with the carboxylic acid in ethanol-water solution. The respective equations for these reactions are shown below. 3

35 2 RCOOH + Cu 2 CO 3 (OH) 2 [Cu(RCOO) 2 ] + 2 H 2 O + CO 2 2 RCOO - + Cu 2+ [Cu(RCOO) 2 ] Cu(CH 3 COO) + 2 RCOOH [Cu(RCOO) 2 ] + 2 CH 3 COOH There are 250 X-ray crystal structures containing [Cu 2 (RCO 2 ) 4 ] in the Cambridge Structural database, and out of these, there are 126 complexes of the type [Cu 2 (OOCR) 4 L 2 ], where L is an axial ligand with an oxygen or a nitrogen donor atom [67]. In this type of structure, two copper(ii) atoms are antiferromagnetically coupled, and their magneto-structural correlation has been studied widely [58]. In these dimeric copper(ii) carboxylates, the carboxylate group displays a variety of coordination behavior, such as monodentate, chelate, and η 1 :η 2 :μ 2 bridging ligands (syn-syn, syn-anti, and anti-anti conformations) [68, 69]. Although, influences of the axial and equatorial ligands to the magnetic properties of this class of compounds, is still much doubtful, many researchers proved that the antiferromagnetic interaction is increased as either L or R becomes a stronger electron donor [70]. In 1992 Kawata et al. [71] showed that the very unique dinuclear complex, copper(ii) benzoate, where benzoate is a bidentate ligand, gave rise to paddle-wheel structure (Figure 2.1),analogous to copper (II) acetate, with Cu-Cu bond length of 2.607(8)Å [72]. Such structure can lead to the growth of supramolecular molecule and polymer-like compound with high potential in industrial application [73-75]. As opposed to its counterpart, copper(ii) acetate or other binuclear copper(ii) alkylcarboxylates, The cage structure of copper(ii) benzoate was proved stronger and more stable due to the existence of high electron density at the bridging groups provided by the phenyl rings, consequently making stronger Cu O coordinate bonds. 4

36 Figure 2.1 Paddle-wheel structure of dimeric copper(ii) benzoate [71] Melnik et al. [76] reported a dinuclear complex, bis(µ-benzoato- O, Oʹ)(dimethylsulphoxide)copper(II), [Cu(C 6 H 5 COO) 2 (DMSO)] 2. It was obtained as dark green crystals when anhydrous copper(ii) benzoate was dissolved in dimethylsulphoxide (DMSO). The complex had a dimeric and square pyramidal geometry at each Cu(II) centre bridged by four benzoato ligands at the equatorial positions and DMSO molecules at the axial positions (Figure 2.2). Figure 2.2 Crystal structure of [Cu 2 (C 6 H 5 COO) 4 (DMSO) 2 ] [76] In 2004 Hu et al. [77] isolated [Cu 2 (4-FC 6 H 4 COO) 4 (C 2 H 5 OH) 2 ] as blue plates in monoclinic system with space group C 2/c, in good yield. The dimeric structure of the complex (Figure 2.3) composed of two Cu(II) atoms coordinated by four 4-fluorobenzoato ligands at equatorial and two ethanol molecules at axial positions. Its crystal packing was stabilized by intermolecular O-H O hydrogen bonds. 5

37 Figure 2.3 Crystal structure of [Cu 2 (4-FC 6 H 4 COO) 4 (C 2 H 5 OH) 2 ] [77] Later in 2011, Mohamadin et al. [78] synthesized the same complex by metathesis reaction between copper(ii) acetate and p-fluorobenzoic acid in hot ethanol. They characterized the complex spectroscopically to adopt a binuclear, paddle-wheel structure with axially ligated ethanol molecules. The asymmetric (ν asym ) and symmetric (ν sym ) stretching bands were observed in its FTIR spectrum at 1427 cm -1 and 1549 cm -1, respectively. The value of ν ( ν = ν asym - ν asym = 122 cm -1 ) suggested bidentate symmetric bridging COO groups of the carboxylate ligand in the complex [79, 80]. Its UV-vis spectrum in MeOH/AcOH acid (20:1 v/v) showed two typical absorption peaks at 697 nm (band I) and 380 nm (band II). Band I was for the d-d transition of Cu(II) with a square pyramidal geometry [81]. Band II (a shoulder peak) suggested a dimeric complex in the solvents [82]. The effective magnetic moment value for the complex was 1.91 B.M., which was higher than copper(ii) benzoate (1.4 B.M.) [83]. The authors suggested that the presence of F atom at the phenyl ring resulted in a strong inductive effect which pushed the electron density towards the central copper atom, preventing back bonding to occur thus prohibit any electronic interaction through the ligands (so called superexchange pathway) [84-86]. The complex was found to be thermally 6

38 stable up to 280 C, and suffered three stages of decomposition process and the residue was mainly CuF 2 [87]. The differential scanning calorimetric (DSC) curve showed three small endotherms at 100, 150 and 190 C respectively, which was in accord with TG analysis data, indicating the primary weight loss due to solvated molecules and the beginning of a major decomposition process. In 2013, Jenniefer and Muthiah [88] reported similar centrosymmetric dinuclear complex but composed of 4-chlorobenzoate ligands, [Cu 2 (4-ClC 6 H 4 COO) 4 (isopropanol) 2 ] (Figure 2.4). The complex adopted similar paddle-wheel cage structure with a distorted octahedral geometry. The syn-syn arrangement of carboxylate groups brought the copper(ii) atoms close enough to allow copper-copper interaction [89]. The shorter Cu-Cu distance (5) Å [69, 90], was within the normal range for dinuclear paddle-wheel units in Cu(II) carboxylates [69, 91-97]. The axial N-Cu-Cu-N and O-Cu-Cu-O bond lengths were almost same as that of (Cu-Cu and Cu-N) and (Cu-Cu and Cu-O) bond lengths, respectively. Thus the contraction of Cu-Cu bond was compensated by the axial Cu-N or Cu-O bond elongation. The value of Δν (183 cm -1 ) from IR spectra suggested symmetrically bridged coordinated carboxylate ligand [69, ]. 7

39 Figure 2.4 ORTEP view of [Cu 2 (4-ClC 6 H 4 COO) 4 (isopropanol) 2 ] [88] Youngme et al. [96] reported a dinuclear tetracarboxylato-bridged Cu(II) complex, [Cu 2 (3-HOC 6 H 4 COO) 4 (4-acetylpyridine) 2 ].6H 2 O (Figure 2.5). Its structure consisted of centrosymmetric dinuclear paddle-wheel unit. Four 3-hydroxybenzoato and two 4-acetylpyridine ligands showed similar coordination to adopt the square-pyramidal coordination geometry. The significant bond distances [Cu O = to Å; Cu N = 2.181(2) Å; and Cu Cu = 2.654(1) Å] were in the ranges typical for dinuclear paddle-wheel units in Cu(II) carboxylates. The basal plane was non-planar with a slight tetrahedral twist of 17.2(1) and the Cu atoms lie Å above the basal plane toward the axial sites. The crystal lattice was stabilized by hydrogen bonding between the O water and O carboxylate atoms of neighbouring carboxylato group, and between O water and O hydroxy atoms of neighbouring 3-hydroxybenzoate ligand. The O O distances (2.591(1) to 3.257(1) Å) generated a one-dimensional chain in the lattice. 8

40 Figure 2.5 Crystal structure of [Cu 2 (µ-o 2 CC 6 H 4 OH) 4 (C 7 H 7 NO) 2 ].6H 2 O [96] Variable temperature magnetic susceptibility study showed that at 350 K, the χ M T value for the above complex was cm 3 mol -1 K. This value was lower than the spin-only value for two non-interacting Cu(II) ions (0.75 cm 3 mol -1 K at RT). On lowering the temperatures, the χ M T value dropped gradually to cm 3 mol -1 K at 50 K, and remained constant until 5 K. This behavior indicated a strong antiferromagnetic interaction among the two copper(ii) centres. Schatzschneider et al., [102] reported carboxylate-bridged copper complex [Cu 2 (μ-l) 4 (S) 2 ], (S = solvent) with pendant nitronyl nitroxide (NIT) radical substituents (Figure 2.6). The complex was synthesized by ligand exchange reaction involving copper(ii) acetate and 4-carboxyphenyl-NIT (HL 1 ). Crystal structure determinations of the complex showed a dimeric arrangement with Cu Cu bond length of 2.629(1) Å. Four nitronyl nitroxide ligands (L 1 ) bridged the copper ions. In the FTIR spectrum the N-O stretching vibration of the NIT were observed at 1359 cm -1 and antisymmetric and symmetric ν(c-o) stretching bands were appeared at around 1400 and 1550 cm -1, respectively, in agreement with a bidentate-bridging coordination manner [79, 103]. The 9

41 magnetic susceptibility measurements revealed dominant exchange interactions between the two copper(ii) ions with J Cu-Cu = 150 cm -1. Figure 2.6 Molecular structure of tetrakis(μ-4-nit-benzoato)dicopper(ii) [102] The synthesis, spectroscopic and structural characterization, and magnetic behavior of another dinuclear copper(ii) carboxylate, tetrakis(diphenylacetato-μ-o, O ) bis(acetone-o)dicopper(ii) was described by Agterberg et al. [104]. The complex crystallized in the triclinic space group P-1. Its molecular structure (Figure 2.7) showed two copper(ii) ions bridged by four carboxylate anions in a syn-syn mode, forming a paddle-wheel unit with intramolecular Cu Cu separation of (4) Å. The average equatorial Cu O distance was Å, and the square-pyramidal geometry around copper was accomplished by an acetone O at (15) Å at the axial position. The Cu...basal plane distance was 0.185(1) Å. 10

42 Figure 2.7 Molecular structure of tetrakis(diphenylacetato-μ-o, O )bis (acetone-o)dicopper(ii) [104] The IR spectrum of the above complex gave the ν value equals 238 cm -1, which suggested bridging bidentate coordination of the carboxylate ligands. Its UV-visible spectrum showed broad bands at 699 nm (xy-polarized band I) assigned to 2 2 d xy, d yz d x -y transitions [105], and at approximately 400 nm (z-polarized band II) [105], as a shoulder. Both were in the typical range for copper(ii) complexes in a square-pyramidal CuO 5 chromophore [106]. The temperature-dependent magnetic susceptibilities of the complex indicated that the S = 1 system revealed from spin interactions between two Cu(II) ions (d 9 ) through conjugated π-system of the carboxylate bridges, the so-called superexchange pathway [107]. In such complex, as the unpaired electron density of both Cu(II) ions was shifted to the same orbital of the bridging carboxylale ligand, so this interaction was strongly antiferromagnetic Copper carboxylate-cyclam complexes There were reports that the paddle-wheel motif of copper(ii) carboxylates may or may not formed in solution, especially in the presence of N-donor ligands. Moreover, these labile complexes were reported to have subnormal magnetic properties as a result of a strong anti-ferromagnetic coupling between the two Cu(II) centres through the bidentate 11

43 bridging carboxylate ligands (the superexchange pathway) [108], making them undesirable for certain applications, such as in molecular magnetism [109]. In contrast, cyclam (1,4,8,11-tetraazacyclotetradecane), which is a N 4 -donor macrocyclic ligand, was reported to form stable mononuclear complexes with many Cu(II) ions [110]. Some examples are [Cu(cyclam)(H 2 O) 2 ](C 6 H 5 COO) 2 [111], [Cu(cyclam)(H 2 O) 2 ] (p-ch 3 C 6 H 4 COO) 2.H 2 O [112], [Cu(cyclam)(H 2 O) 2 ](C 6 F 5 COO) 2 [113], [Cu(cyclam)(H 2 O) 2 ](CH 3 (CH 2 ) 5 COO) 2.2H 2 O [114], and [Cu(cyclam)(H 2 O) 2 ] (CH 3 (CH 2 ) 8 COO) 2.2H 2 O [115]. These ionic complexes have weakly coordinating solvent molecules at both axial positions of Cu(II). Hence, by simply choosing a correct carboxylate ion, these complexes may function as low-temperature ionic metallomesogens, metal-based ionic liquids [116], and act as monomers for linear-chain magnetic coordination polymers [117]. In 2003 Lindoy et al.[111] successfully synthesized copper(ii) complexes including cyclam and benzoate or 4-t-butylbenzoate anions by reactingwith the corresponding copper(ii) benzoate (or 4-t-benzoate) with cyclam in methanol. The complexes showed the anticipated 2:1:1 ratio of carboxylate ion to cyclam to Cu(II) ion (Figure 2.8). In each complex s UV-vis spectrum, a broad absorption band in the visible region was observed. 12

44 Figure 2.8 A column of the hydrogen-bonded components of trans-[cu(h 2 O 2 )(cyclam)](c 6 H 5 COO) 2.2H 2 O [111] For most of the cyclam complexes with copper(ii) salts, no cis-octahedral system has been observed. Planar four-coordinate, five-coordinate and six-coordinate are the commonly found systems. In six coordinate complexes the axial metal-ligand bonds are predictably both longer and variable in length [111]. An example of centrosymmetric trans-[cu(h 2 O) 2 (cyclam)] 2+ cation, [Cu(H 2 O) 2 (cyclam)]f 2.4H 2 O, was described by Emsley et al. [118, 119]. The complex crystallized in the monoclinic system with space group C 2/m. The six-coordinate copper atom was located on a crystallographic inversion centre, where one half of the formula unit involved in the asymmetric unit of the structure. The anion and water molecules made [F(OH 2 ) 4 ] - entities; that were connecting and connected by the cations into a three-dimensional hydrogen-bonded network. 13

45 The author found an analogous situation for [Cu(H 2 O) 2 (cyclam)] (4-t-butylbenzoate) 2, but there was no lattice water. The packing mode was similar, revealed a similar c cell dimension as above, although the lack of lattice hydration simplifies the environment of the columnar array (Figure 2.9). Cu O bond length was no longer similar, found in the corresponding benzoate and fluoride complexes. Figure 2.9 A column of the hydrogen-bonded components of trans-[cu(h 2 O) 2 (cyclam)](4-t-butyl-benzoate) 2 [111] In 2010 Ahmad Tajidi et al. [112] reported [Cu(cyclam)(H 2 O) 2 ] (4-CH 3 C 6 H 4 COO) 2.2H 2 O, where chelation of four N atoms of cyclam ligand and coordination of two water molecules to Cu(II) ion gave rise to a Jahn Teller type of tetragonally distorted octahedral geometry. The cations, anions and lattice water 14

46 molecules were interrelated by N H O and O H O hydrogen bonds to generate a layer structure parallel to (0 0 1) (Figure 2.10). Figure 2.10 Crystal structure of [Cu(cyclam)(H 2 O) 2 ](4-CH 3 C 6 H 4 COO) 2.2H 2 O [112] These authors in the same year reported another analogous complex, [Cu(cyclam)(H 2 O) 2 ](C 6 F 5 CO 2 ) 2.2H 2 O [113] (Figure 2.11). Figure 2.11 Crystal structure of [Cu(C 10 H 24 N 4 )(H 2 O) 2 ](C 6 F 5 -CO 2 ) 2.2H 2 O [113] 2.2 Dinuclear copper carboxylate metallomesogens A metallomesogen is a metal containing liquid-crystalline compound of organic ligand that shows the same type of mesophase that found in purely organic liquid crystal [1, 4, 5, 14, ]. The interactions between the anisometric molecules such as dipole-dipole interactions, van der Waals interactions, π-π stacking are the driving 15

47 forces for the development of a liquid-crystalline phase (mesophase) in metallomesogens [128]. Although research on metallomesogens is ruled by mononuclear complexes [129], but introducing additional metal centers could give rise to fascinating effects, such as ferromagnetism, antiferromagnetism, or mixed oxidation states from which new magnetic or electronic behavior and materials may arise. Among the various metallomesogens already explored, the binuclear carboxylates of divalent transition metal ions, of general formula [M 2 (RCO 2 ) 4 ], have been widely studied for M = Cu(II), Rh(II), Ru(II), Mo(II), Pd(II) and Cr(II) [15]. Some examples are shown in Scheme 2.1. (a) (b) (c) Scheme 2.1 (a) dinuclear azopalladium(ii) complex; (b) alkoxy-substituted bis (1,5-diphenyl-1,3,5-pentanetrionato)dicopper(II) complex; and (c) dinuclear tetraalkanoatecopper(ii) complex; R = long alkyl(oxy) chain The challenging probability of relating the anisotropy and fluidity of liquidcrystalline phases with the properties originated from the presence of d electrons in the transition-metal complexes is the basis of the increasing interest and rapid growth of metallomesogen [4, 14, 120, 121, 124, 130]. Another advantage of metallomesogens is that these complexes allow for facile alignment using the weaker magnetic field. A stronger interaction between the diamagnetic organic liquid crystals and the magnetic 16

48 field is obtained by the inclusion of paramagnetic metal ions into liquid crystalline compounds. In metal-carboxylate liquid crystals, intermetallic separations ranging from either very large (6.524 Å and Å) [131], to very small (2.17 Å) [132] or can be intermediate, (~ 3.0 Å), with bridging ligands connecting the metals [133]. The intermediate metal-metal distances lead to the strongest magnetic coupling, although in binuclear complexes the Cu(II) atoms located at a long distance, for example a 10 Å pathway [134], show magnetic coupling. In magnetically non dilute compounds, the electronic structure, as deduced by magnetic coupling, is established by molecular structure. Thus magnetic measurements can be a key in structural determination. The ability to control the position and orientation of transition metals in multinuclear complexes permits the design of new materials to show useful electronic and magnetic properties [7-9, 11, 12]. The first thermotropic metal-carboxylate liquid crystals were reported by Vorlander in 1910 [135]. In 1964 Grant [136] observed the mesomorphic behaviour of dinuclear copper(ii) carboxylates, but their mesophases were thoroughly investigated and characterized by Giroud s [137] research group in the eighties. In 1990 Attard et al. [138] reported that copper(ii) carboxylates can promote the formation of discotic mesophase (Figure 2.12). This behavior is a result of the disc-like shapes of the polar cores of the molecules which comprise of two copper(ii) sites coordinated with four carboxylate ligands. The symmetry of such complex lattice is generally hexagonal. These complexes have low magnetic moments because of the spin exchange between the unpaired electrons in each copper(ii). It was assumed that the combination of discotic mesophase and the electronic properties of the dinuclear cores could give rise to remarkable conductance effect [139]. 17

49 Figure 2.12 Discotic mesophase of a copper(ii) carboxylate [138] Indeed, a number of attempts has been taken to prepare the one-dimensional polymer [Cu 2 (μ-o 2 CC n H 2n+1 ) 4 (pz)] (n = 9, 15), which unsuccessfully were not mesogenic. In the same way copper derivatives polymerized by 4,4ʹ- bipyridine were not mesomorphic. The only complex proved promising was a branched chain carboxylate copper complex, although its mesophase was not fully characterized. But a series of analogous tetrakis(benzoato)dirhodium complexes substituted with diverse numbers of aliphatic chains were synthesized by Barbera et al. [140] in 1992 and Rusjan et al. [141] in These molecules composed of four aromatic rings involved to the dinuclear benzoate unit, generating a large central core and observed to show columnar mesophase, the symmetry of which determined by the number of peripheral chains bonded to the phenyl rings. With overall four chains, the columnar mesophase adopt a rectangular symmetry and a regular intracolumnar stacking with the chains directed in one preferred way instead of surrounding the central core. The complexes, [Rh 2 (μ-o 2 CC 6 H 4-4-OC n H 2n+1 ) 4 ] (n = 8-14; Figure 2.13) were prepared by the ligand exchange reaction involving molten [Rh 2 (μ-o 2 CCH 3 ) 4 ] and the corresponding 4-(alky1oxy)benzoic acid [140]. 18

50 Figure 2.13 Rhodium(II) 4-alkyloxybenzoates [140] The Δν values from the IR spectra of the above complexes were about 160 cm -1, suggesting bridging coordination of the benzoato ligands [79]. The 1 H-NMR spectra confirmed that the four benzoate ligands were equivalent, in agreement with the proposed structure (Figure 2.13). However, the signals for aromatic protons were broad, and no coupling constants were obtained. They explained this broadness as a consequence of the presence of a little amount of coordinated solvents or paramagnetic impurities [142]. These complexes (n 10) showed mesogenic properties too. Figure 2.14 shows the first DSC scans for [Rh 2 (μ-oocc 6 H 4-4-OC 10 H 21 ) 4 ]. The heating scan shows two endothermic peaks, at 156 C, assigned to crystalline-to- mesophase (M) transition, and at 203 C, assigned to M-to-isotropic liquid phase (I) transition. The cooling scan showed a peak for I-to-M transition, but instead of the exothermic M-to-crystal transition, it showed two new transitions with lower energy. 19

51 Figure 2.14 DSC thermogram of the first heating and cooling processes for [Rh 2 (μ-oocc 6 H 4-4-OC 10 H 21 ) 4 ]. An asterisk indicates the peak due to the endothermic loss of small amounts of coordinated water [140] The other mesogenic members of this series showed thermal behaviors similar to [Rh 2 (μ-oocc 6 H 4-4-OC 10 H 21 ) 4 ]. All complexes displayed similar temperatures of isotropization, whereas the temperature range for mesophase stability widen, with the increasing length of the alkyloxy chain. The supercooling phenomena achieved for the M-to-I transitions persisted even at very slow scanning rates. The complexes were thermally stable, started to decompose at temperatures above 240 C. On cooling from isotropic liquid phase,the complex was observed to show the mosaic texture of mesophase (Figure 2.15), that was not affected by two low-energy exotherms observed in DSC and remained unchanged up to room temperature. In successive heating and cooling cycles, only the peaks existent in the cooling scan were found. This behavior indicated that after a heating and cooling cycles, the sample crystallized into a solid phase which differed from the starting crystal phase. 20

52 Figure 2.15 The mesophase of [Rh 2 (μ-oocc 6 H 4-4-OC 11 H 23 ) 4 ] viewed under crossed polarizers [140] 2.3 Mononuclear copper carboxylate-cyclam metallomesogens Studies on numerous types of macrocyclic structures, have revealed that they form discotic metallomesogens, which were capable of inducing columnar phases due to their molecular shape [143]. Such columnar organization of disk-like mesogens is a potential architecture for anisotropic materials with applications such as one dimensional conductors [144], photoconductors [145], molecular wires and fibers [33, 146], light emitting diodes [147] and photovoltaic cells [148]. Examples of commonly used macrocyclic ligands are: (a) tridentate ligands, such as 1,4,7-triazacyclononanes [37]; (b) tetradentate ligands, such as phthalocyanines [38-40], porphyrins [41, 42], tetraazaporphyrins [43], and tetraazacyclotetradecanes [44]; (c) hexadentate ligands, such as hexaazacyclooctadecanes [45]; and (d) octadentate ligands, such as bisphthalocyanines [46, 149]. A wide range of transition metals, such as Co, Ni, Pd, Cu, Zn, Pt, Pb, Cr, Mo, W, Lu, have been fused in such ligands to attain discotic molecules showing hexagonal or rectangular columnar phases [149]. Two motivating advantages of macrocyclic metallomesogens reported by researchers are more stability of their mesophases compared to open chain analogues [150] and self-assembly properties that make them more desirable for manufacturing purposes when producing commercial electronics 21

53 specially [151]. However, there are only few examples of metallomesogens based on 1,4,8,11-tetraazacyclotetradecane (cyclam) reported in the literature. A family of ionic macrocycles [152] and their corresponding metal complexes [149] originated from the potential discotic mesogens tetrabenzo[b,f,j,n][1,5,9,13]- tetraazacyclohexadecane (Figure 2.16: M = Cu; n = 10,12,14,16,18) have been described. The self-condensation of 3,4-dialkoxy-2-aminobenzaldehydes in the presence of HBF 4 resulted in the formation of tetrafluoroborate salts of deprotonated octaalkoxy macrocycles. These salts were then reacted with the appropriate metal acetate to obtain the metal complexes. The metal free macrocycles (Figure 2.16, where M = 2H, n = 8, 10, 12) explored previously by Kang et al. [152], observed to show a Col h phase from room temperature up to 270 C, depending on the chain length. The similar columnar phases were expected to develop for the corresponding metal complexes as well. OC n H 2n+1 2+ H 2n+1 C n O OC n H 2n+1 H 2n+1 C n O N N M N N OC n H 2n+1 H 2n+1 C n O OC n H 2n+1 OC n H 2n+1 Figure 2.16 Metallomesogenic tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane (M = 2H; n = 8, 10, 12 [127]; M = Cu; n = 10, 12, 14, 16, 18 [149]) The above complexes exhibited liquid crystalline behavior. The crystal-tomesophase transition temperatures were determined by differential scanning calorimetry (DSC) analysis. Though, columnar-to-isotropic transition temperatures could not be 22

54 detected by DSC, and authors proposed it was because of a comparatively low transition enthalpy change for this transition. It indicated a highly disordered columnar phase. Similar phenomenon was also observed in metal-free compounds [152] and is probably a nature of the macrocycle ring regardless of the presence or absence of a metal ion. All complexes displayed an enantiotropic Col h phase but with some variationin the mesophase stability upon metallation. The mesophase developed at or close to room temperature (n = 10 to 14) and at about C (n = 16, 18), whereas the range of clearing temperatures was C. The clearing temperatures decreased as n increased from as shown in Table 2.1 [149]. Table 2.1 The Thermotropic behavior of Cu(II) complexes of tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane [149] n Phase transition 10 Col h.196. I 12 Col h.194. I 14 Cr.26.Col h.190. I 16 Cr.58.Col h.190. I 18 Cr.66.Col h.183. I The authors mentioned that when viewed under optical polarizing microscope, similar pseudo-focal conic texture (Figure 2.17) typical of columnar mesophases, was observed for metal free ligand tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane (Figure 2.16: n = 12) and for complexes. Figure 2.17 Texture of tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane viewed under a polarizing microscope at 70 C [152] 23

55 In 2015 Norbani et al. [153] reported a mesomorphic Cu(II) complex with 1,4,8,11-tetraazacyclotetradecane ligand, [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2 (where, L = 4-hexadecyloxypyridine). Its phase transition temperatures and enthalpy changes are summarized in the following scheme (Cr = crystal, M = mesophase, I = isotropic liquid phase): Cr 70.0 o C M 127 o C kj mol -1 I Figure 2.18 Photomicrograph of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2 at C, on cooling from the isotropic liquid phase [153] 2.4 Nickel arylcarboxylates Structures and properties The electronic configuration of nickel is [Ar]4s 2 3d 8. Thus, its most stable ion is Ni 2+ ([Ar]3d 8 ), but compounds of Ni 0, Ni +, and Ni 3+ are familiar too, as well as unusual oxidation states Ni 2, Ni, and Ni 4+. However, Ni(II) complexes exist in the common geometries: octahedral, tetrahedral and square planar [154]. The dinuclear metal carboxylates consist of bridging bidentate carboxylate ligands along with oxo, aqua or hydroxo bridging ligands are well known in nickel chemistry. In 2006, Karmakar et al. [155] described the synthetic and structural aspects of a few binuclear nickel(ii) complexes containing bridging aqua ligand. A representative complex is [Ni 2 (μ-h 2 O)(μ-PhCOO) 2 (PhCOO) 4 (C 5 H 5 N) 4 ].1.5C 6 H 6. It was synthesized by the solid- 24

56 state reaction of nickel(ii) chloride hexahydrate with sodium benzoate in 1:2 stoichiometry, followed by the addition of pyridine. It was readily soluble in chloroform, benzene and toluene, and isolated from benzene as light blue block crystals with space group P 2 1 /c. The crystal structure revealed that each nickel centre adopted octahedral geometry involving two bridging benzoate, two coordinated pyridine, a monodentate benzoate and a bridging aqua ligands (Figure 2.19). The Ni(1) Ni(2) bond distance was 3.506(3) Å. The monodentate benzoate ligand was intramolecularly hydrogen-bonded to the bridging aqua ligand through O water -H O COO (2.565, Å, 166, 170 ) bonds,was in the origin of its structural stability. The Ni(1) O water and Ni(2) O water bond lengths were 2.093(2) and 2.094(2) Å, while the Ni(1) O(9) Ni(2) bond angle was 113.7(8). The structure was stabilized by weak aromatic C H π interactions (d C π =3.87 Å) involving the C60 H of the benzene molecule as the donor and the aromatic ring of the benzoate ligand as the acceptor. Its UV-vis spectra showed an absorption maximum at 645 nm due to a 3 A 2g 3 T 1g transition from d 8 electronic configuration in a weak field. Figure 2.19 Crystal structure of [Ni 2 (μ-h 2 O)(μ-PhCOO) 2 (PhCOO) 4 (C 5 H 5 N) 4 ].1.5C 6 H 6 [155] 25

57 The above authors [155] reported another aqua-bridged binuclear nickel(ii) complex consisted of 2-NO 2 substituted benzoate, [Ni 2 (H 2 O)(2-NO 2 PhCOO) 4 (Py) 4 ] (Figure 2.20). It was prepared by adding pyridine to a mixture of nickel(ii) chloride hexahydrate, 2-nitrobenzoic acid and potassium hydroxide in solid-state. The synthetic procedure was recommended to follow strictly as the analogous reaction in solution led to the formation of a mononuclear species [156]. However the resulting complex crystallized from toluene as blue-green plates in the C 2/c space group. Its crystal structure showed that each nickel(ii) centre was connected by two bridging benzoato and bridging aqua ligands. A six-coordinate octahedral geometry around each nickel(ii) was accomplished by the coordination to one monodentate benzoato and two pyridine ligands. The monodentate benzoato ligand was intramolecularly hydrogen-bonded to the bridging aqua molecule through O(9) H O(2) [2.571(16) Å, 167(2) ] interactions. The corresponding Ni(1) O(9) bond length was 2.089(9) Å with the Ni(1) O(9) Ni(2) bond angle (8). Figure 2.20 Crystal structure of [Ni 2 (H 2 O)(2-NO 2 PhCOO) 4 (Py) 4 ] [155] The same authors reported [Ni 2 (H 2 O)Cl(4-ClC 6 H 4 COO) 3 (py) 4 ], formed in similar synthetic method as above example, using 4-chlorobenzoic acid [155]. The crystal 26

58 structure showed an aqua bridge, a 4-ClC 6 H 4 COO bridge (Figure 2.21), and unlike the previous complex, a chloride bridging group linked the two nickel centres. The effect of such bridging by both chloro and aqua group reflected in the smaller Ni O aqua Ni bond angle (9). All other bonding modes, lengths and angles were comparable to former complex. Each nickel centres had a distorted octahedral geometry, and λ max in methanol was 633 nm (ε max = M 1 cm 1 ) due to the 3 A 2g to 3 T 1g transition. Figure 2.21 Crystal structure of [Ni 2 (H 2 O)Cl(4-ClC 6 H 4 COO) 3 (py) 4 ] [155] In 2011, Niu et al.[157] observed weak antiferromagnetic interactions between two Ni(II) atoms in the complex, [Ni 2 (L) 2 (py) 4 (H 2 O)] (H 2 L = 1,1ʹ-biphenyl-3,3ʹdicarboxylic acid; Figure 2.22), synthesized by hydro/solvothermal and solventdiffusion methods. 27

59 Figure 2.22 Ball-stick diagram of the coordination arrangement around the Ni centers for [Ni 2 (L) 2 (py) 4 (H 2 O)] n [157] The variable temperature magnetic susceptibility of the above complex showed that in the temperature range of K, the χ M T value was about 2.4 cm 3 K mol -1, gradually reduced to 2.32 cm 3 K mol -1 at 4 K, and then sharply decreased to 2.12 cm 3 K mol -1 at 1.8 K (Figure 2.23). This rapid decrease may be attributed to inter layered antiferromagnetic exchange interactions and zero-field splitting (ZFS). From 1.8 to 300 K, magnetic susceptibility obeyed the Curie-Weiss law with Weiss constant (θ) = K and Curie constant (C) = 2.41 cm 3 K mol -1, indicating very weak antiferromagnetic interactions between two Ni(II) atoms. Figure 2.23 Plot of χm and χ M -1 vs T for [Ni 2 (L) 2 (py) 4 (H 2 O)] n [157] 28

60 2.4.2 Nickel carboxylate-cyclam complexes The Ni(II) complexes with 1,4,8,11-tetraazacyclotetradecane macrocycle are thermodynamically and kinetically stable [158], which permits its use in catalytic reactions, sometimes even under severe conditions [159]. A study of Cambridge Structural Database showed that among 139 nickel-cyclam complexes, trans-iii was the most frequently found configuration for octahedral, whereas trans-i was common for square-planar complexes [160]. The ideal Ni-nitrogen bond distances were approximately 1.9 Å and 2.1 Å for square planar and octahedral nickel-cyclam complexes, respectively [161]. In 1987, Connolly and Billo [162] carried out a spectroscopic study of Ni(II) ion, using 1 H-NMR spectra of [Ni(cyclam)](ClO 4 ) 2, and discovered that the most frequently found configuration was the lowest energy configuration, trans-iii. Their NMR measurements and molecular mechanics calculations are shown in Table 2.2. Table 2.2 Relative strain energies (kcal mol -1 ) for planar and octahedral conformers of Ni(II) cyclam complexes [162] Conformer Planar Octahedral trans-i trans-ii trans-iii 0 0 trans-iv trans-v The study of absorption spectra of numerous pseudo-octahedral nickel(ii) complexes with macrocyclic ligands [ ] showed that usually two or three bands arise due to the d-d transitions, in the ranges nm (ν 1 ), nm(ν 2 ), and nm (ν 3 ) with low extinction coefficients (10-40 M -1 cm -1 ). The flexibility of cyclam to host a wide range of guest metal ions with large association constant has developed remarkable growth to the synthesis of coordinated transition metal mononuclear complexes, comprising carboxylates as the counterions 29

61 [110]. The O carboxyl atoms is either being coordinated to the metal, or might not be directly coordinated, hence exist as free ions. In 2003, Lindoy et al.[111] synthesized nickel(ii) complexes including cyclam and benzoate anion by reacting the corresponding metal benzoate with cyclam in methanol. The X-ray crystallography of resulting complex [Ni(O-benzoate) 2 (cyclam)] showed benzoate anions directly coordinated to Ni 2+. The complex had the expected 2:1:1 ratio of carboxylate ligand: cyclam: Ni(II) ion (Figure 2.24). The stereochemistry was trans as the Ni(II) atom was disposed on a crystallographic centre of symmetry, in orthorhombic space group Pbca. The Ni-O(11), Ni-N(1), and Ni-N(5) bond distances were 2.126(2), 2.074(2) and 2.052(2) Å, respectively. The Ni-O(11)-C(111) angle was 131.5(1). The uncoordinated carboxylate oxygen atom was intramolecularly hydrogen bonded to one of the cyclam hydrogen atoms, Ni N to the latter was markedly longer than its counterpart. The cyclam ligand existed in the most stable trans-iii configuration. The visible spectrum of this purple complex in methanol showed absorptions at 522, 635, 721, 873 and 975(sh) nm, indicating a tetragonally distorted octahedral coordination geometry [111]. 30

62 Figure 2.24 Projection of the centrosymmetric molecule of trans-[ni(o-benzoato) 2 (cyclam)] [111] Later in 2010, Lim et al. [178] synthesized [Ni(cyclam)(H 2 O) 2 ](fumarate).4h 2 O (Figure 2.25) which crystallised in triclinic system with space group P -1. In this complex, the fumarate anions were not directly coordinated to the Ni 2+ atom. The asymmetric unit of the complex included half of a nickel(ii) complex dication, half of a fumarate dianion and two water molecules. Both Ni 2+ and fumarate anion lied on a crystallographic center of inversion. The six-coordinated Ni 2+ ion was within a distorted N 4 O 2 octahedral geometry, where four cyclam N atoms were in the equatorial plane and two water molecules were in axial positions. The six-membered ring existed in the chair conformation while the five-membered ring adopted a twisted form. Intermolecular hydrogen bonds (O H O) between the water molecules and the uncoordinated oxygen atom of carboxyl groups of the fumarate anions resulted in the formation of layers with (8) ring motifs. Ni 2+ complex cations were fit in between 31

63 two such layers, and held in place by O H O, N H O and C H O hydrogen bonds, generated a three-dimensional web. Figure 2.25 Molecular structure of [Ni(cyclam)(H 2 O) 2 ](fumarate).4h 2 O [178] 2.5 Dinuclear nickel carboxylate metallomesogens There is no report found in literature for dinuclear nickel-tetracarboxylates with mesogenic properties. 2.6 Mononuclear nickel carboxylate-cyclam metallomesogens Kang et al. [152] in 1999 and Wu et al. [149] in 2001 reported a group of ionic macrocycles and their analogous metal complexes, respectively, originated from the potential discotic mesogens tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane (Figure 2.26; n = 10,12,14,16,18). OC n H 2n+1 2+ H 2n+1 C n O OC n H 2n+1 H 2n+1 C n O N N Ni N N OC n H 2n+1 H 2n+1 C n O OC n H 2n+1 OC n H 2n+1 Figure 2.26 Ni(II) complex of tetrabenzo[b,f,j,n][1,5,9,13] tetraazacyclohexadecane (n = 10,12,14,16,18) [149] 32

64 All of the above complexes displayed an enantiotropic Col h phase but with some shift of the mesophase stability due to metallation. The mesophase developed at or close to room temperature (for n = 10 to 14) and at around C (for n = 16 and 18) while clearing temperatures were in the range C. Both of these temperatures decreased as n increased from 10-18, as shown in Table 2.3. The results showed that the stability of the mesophase increased upon complexation of this ligand to nickel(ii) compared to Cu(II) (Table 2.1 in Section 2.3). Table 2.3 Thermotropic behavior of Ni(II) complexes of tetrabenzo[b,f,j,n][1,5,9,13]tetraazacyclohexadecane [149] n Phase transition 10 Col h 290 I 12 Col h 270 I 14 Cr 28 Col h 265 I 16 Cr 59 Col h 238 I 18 Cr 52 Col h 234 I The above authors mentioned that when viewed under optical polarizing microscope, similar pseudo-focal conic texture (Figure 2.17 in Section 2.3), typical for columnar mesophases, were observed for the metal complexes. 2.7 Cobalt arylcarboxylates Structures and properties The electronic configuration of cobalt is [Ar] 3d 7 4s 2. Its common oxidation states are +2 and +3. In 1783, Wertzel [179] reported the reaction of cobalt(ii) oxide with acetic acid produced [Co(CH 3 CO 2 ) 2 (OH 2 ) 4 ]. This simple formulation led to a variety of structural types (stoichiometries, geometries, and physical properties) in the chemistry of cobalt(ii) carboxylates. These complexes have applications as catalysts [180], and the magnetism of high-spin pseudooctahedral cobalt(ii) compounds has been a subject of enduring interest [181, 109], because their high anisotropy and d 7 electronic configuration lead to interesting magnetic properties. In particular, the presence of 33

65 bridging carboxylate ligands provides a potential route for magnetic exchange between adjacent metals [182]. Hudák et al. [183] discovered that cobalt(ii) carboxylates showed a variety of structural motifs (Figure 2.27): (a) type I: a structural analogs of copper(ii) acetate: [Co 2 (bz) 4 L 2 ], in which four benzoato ligands (bz) act as bridges that connect two metal ions. Examples are pentacoordinated Co(II) complexes [(μ 2 -bz) 4 {Co(qu)} 2 ] and [(μ 2 -bz) 4 {Co(4-Me-qu)} 2 ], where qu = quinoline [ ]; (b) type II: one aqua and two benzoato bridging ligands link two metal sites. In most cases, additional benzoate ions act as unidentate terminal ligands. Hence, the hexacoordination around cobalt(ii) ions in these complexes are mostly completed by N-donor bases. Similar structural motif also common for substituted benzoates, n-x-bz (where n = 2, 3, and 4) [187, 188]; (c) type III: two metal ions are linked by two benzoato bridging ligands and two aqua bridges for example, [(μ 2 -H 2 O) 2 (μ 2 -) 2 {Co(2,6-(pTol) 2 -bz)(py)} 2 ](2,6-(pTol) 2 -bz) (py = pyridine) [189], and (d) type IV: purely aqua bridged complexes with only benzoate ions as terminal ligands exemplified by [(μ 2 -H 2 O) 2 {Co(bpy) 4 (H 2 O) (4-CHO-bz)} 2 ](4-CHO-bz) 2 [183]. 34

66 Figure 2.27 Structural types of dinuclear cobalt(ii) carboxylates [183] However, the most common motifs are types II and III [190]. The synthesis and structure of one such dinuclear aqua-bridged complex, [Co 2 (μ-h 2 O) (μ-c 6 H 5 CO 2 ) 2 (pyridine) 4 ] (Figure 2.28) was described by Karmakar et al. [187] in These authors reported that cobalt(ii) chloride hexahydrate, benzoic acid (BzH) and sodium hydroxide reacted in the solid-state, followed by the addition of pyridine (in 1:2:2 stoichiometry) to form [Co 2 (μ-h 2 O)(μ-Bz) 2 (Bz) 2 (py) 4 ].(C 6 H 6 )(BzH). The complex was obtained as pink plates (space group P 2 1 /c) from benzene. Crystal structure of this complex showed that the cobalt centres were bridged by two benzoato ligands along with a bridging water molecule. Each cobalt(ii) was in an octahedral geometry, with Co(1) Co(2) bond distance of 3.597(3) Å. Six-coordination environment about the metal ion was completed by terminally coordinated two pyridine molecules and a monodentate benzoate group, which in turn were intramolecularly hydrogen-bonded to bridging water molecule. This bonding mode was reflected by a strong absorption at 35

67 3063 cm -1 due to O H stretching in its FTIR spectrum. Its UV-visible spectrum in methanol showed a weak absorption band at 512 nm, and a shoulder at 414 nm, assigned to the 4 T 1g (F) 4 A 2g (F) and 4 T 1g (F) 4 T 1g (P) transitions, respectively [191]. Figure 2.28 Crystal structure of [Co 2 (μ-h 2 O)(μ-Bz) 2 (Bz) 2 (py) 4 ].(C 6 H 6 )(BzH) [187] The room-temperature magnetic moment of the above complex was 6.54 BM, which corresponded to an octahedral cobalt(ii) centre, and indicated the existence of orbital contribution to the spin-only value [192]. The same authors described another complex, [Co 2 (μ-h 2 O)(μ-p-ClBz) 2 (p-clbz)(py)] (Figure 2.29) [187], prepared similarly using p-chlorobenzoic acid, and isolated as pink crystals from toluene. Its crystal structure was similar to the previously described complex. A slight deviation in the Co1 O aqua Co2 separation was observed due to electronic effect and the different environment created by guest molecules. However the observed distances were within the expected values. 36

68 Figure 2.29 Crystal structure of [Co 2 (μ-h 2 O)(μ-p-ClBz) 2 (p-clbz)(py)] [187] In the same year, these authors identified a complex with NO 2 substituted ligands, [Co 2 (µ-oh 2 )(C 5 H 5 N) 4 (µ-o 2 CC 6 H 4-2-NO 2 ) 2 (2-NO 2 OOCC 6 H 4 )] (Figure 2.30) [193]. It was isolated as pink rods in the triclinic space group P -1 from methanol. Its X-ray crystallography showed that one monodentate benzoate molecule and two pyridine molecules were coordinated to each cobalt(ii) ion. The six-coordinationat each cobalt(ii) ion was accomplished by two bridging 2-nitrobenzoate groups and one bridging aqua ligand. There were intramolecular hydrogen bonds between monodentate 2-nitrobenzoate molecule and bridging aqua group, O water H O COO (2.578, Å, 167, 177 ). The Co(1) O water and Co(2) O water bond lengths were found to be and Å, respectively, while the Co(1) O water Co(2) bond angle was (7). Additionally, weak intramolecular C H O interactions in the range [ Å, ], were also observed in this polymorph that stabilized the out-out orientation of the nitro groups of 2-nitrobenzoate ligand relative to the Co(1) O water Co(2) fragment in the complex. In the crystal lattice these molecules self-assembled through weak C H O [3.429(4) Å, 158, 3.279(5) Å, 139 ] interactions. 37

69 Figure 2.30 Crystal structure of [Co 2 (µ-oh 2 )(C 5 H 5 N) 4 (µ-r) 2 R] (R = 2-NO 2 OOCC 6 H 4 ) [193] The presence of intramolecular hydrogen-bonding interactions involving the 2-nitrobenzoate group and the bridging aqua ligand proved by broad peaks centred at 3407 cm -1 (O H stretching) in its solid-state FTIR spectra. It also exhibited absorptions in the carbonyl C=O (~1630 cm 1 ) region and the nitro N O stretching (1390 cm -1 ) region with a shoulder at about 1356 cm 1. Its UV-visible spectrum showed maximum absorption at 521 nm (ε max = M -1 cm -1 ) and its magnetic data gave a value of μ eff = 6.56 BM at 25 K. In 2013, Hudák et al. [183] described the crystal structure and absorption spectra of [(μ 2 -H 2 O)(μ 2 -PhCOO) 2 {Co(PhCOO-κ 1 -O)(Mepy) 2 } 2 ] (Figure 2.31), which crystallized in the monoclinic system with the space group P 2 1. All bond and interatomic distances (Co O1W, Co1 O bc, Co Co and Co-O mc ) of this complex were similar to that of the analogous cobalt(ii) complexes found in the Cambridge crystallographic database [194]. 38

70 Figure 2.31 Molecular structure of [(μ 2 -H 2 O)(μ 2 -PhCOO) 2 {Co(PhCOO-κ 1 -O)(Mepy) 2 } 2 ] [183] The UV-vis spectrum of the above complex showed a number of spin allowed d d transitions followed by an intense charge-transfer band (Figure 2.32). Assuming the ground crystal-field term in the octahedral geometry, 4 T 1g, three d d transitions were observed within 1111 nm and 400 nm range. There was a weak antiferromagnetic interaction between the cobalt(ii) centers. 39

71 (a) (b) Figure 2.32 (a) electronic spectrum; and (b) term diagram of [(μ 2 -H 2 O)(μ 2 -PhCOO) 2 {Co(PhCOO-κ 1 -O)(Mepy) 2 } 2 ] [183] 40

72 2.7.2 Cobalt Carboxylate-Cyclam Complexes In 1965 Bosnich et al. [195] found that the preferred configuration of cobalt-cyclam complexes with monodentate ligand was trans configuration rather than cis. cis-configuration trans-configuration Figure 2.33 Different configurations of cobalt-cyclam complexes [195] An example of a complex showing trans-rssr [CoCl 2 (cyclam)] + cations was synthesized by Sosa-Torres and Toscano [196] in The complex, [CoCl 2 (cyclam)]cl.4h 2 O.0.47HCl (Figure 2.34) crystallized in monoclinic system with P 2 1 /n space group, where the Co(II) atom existed in a crystallographic centre of symmetry. The tetragonally elongated octahedral metal centre comprised of the four nitrogen atoms of cyclam and two Cl atoms. The trans-rssr [CoCl 2 (cyclam)] + cations were arranged into columns along the b direction, forming channels which were engaged by chloride counterion and water molecules. Figure 2.34 Molecular structure of [CoCl 2 (C 10 H 24 N 4 )]Cl.4H 2 O.0.47HCl [196] By the ligand strain minimization method, the "ideal" metal-donor atom distances were calculated as a function of the size of the macro ring [197]. It showed 41

73 that a 14-membered macrocyclic ligand will experience the minimum strain on coordination to the cobalt(iii) and nickel(ii) ions. Yatsimirskii and Lampeka in 1980 [198] investigated the absorption spectra of a group of cobalt-cyclam complexes in the majority of which the donor atoms of the macrocyclic ligand occupy the equatorial plane in the coordination sphere of the metal. The spectra of these high-spin cobalt complexes showed that the metal ion existed in a pseudo-octahedral environment [199, 200] and the monodentate ligands occupy the cispositions in the octahedron. Three absorption bands in the visible region at 1250, 625, and 526 nm, corresponded to the spin-allowed transitions 4 T 2g 4 T 1g, 4 A 2g 4T 1g, and 4 T 1g (P) 4 T 1g, respectively. The magnetic susceptibility values were of the order of BM, which correspond to the presence of three unpaired electrons. To examine the structural and mechanistic behavior of octahedral cobalt(iii)- cyclam complexes, Poon [201] in 1971, investigated the use of infrared spectroscopy as a probe to differentiate between cis- and trans- isomers of cobalt-cyclam complexes [ ]. They found that in each of the following three regions of absorption, ~1600 (NH 2 asymmetric deformation), ~ (NH 2 symmetric deformation), and ~ (CH 2 rocking modes) cm -1, most complexes with a cis-configuration exhibit two bands, while those with a trans- configuration exhibit one. In particular, the bands in the CH 2 rocking region, that are unresponsive to changes in the ligands or anions [205] have been successfully used. The bands in the cm -1 region where Co-N stretching modes take place had also been used. In this region, no trans- complex showed more than three bands, while all cis- complexes showed at least four bands [206, 207]. As examples, the infrared spectra of the four known cis-trans pairs of [CocyclamCl 2 ]Cl (A), [Cocyclam(N 3 ) 2 ]NO 3 (B), [Cocyclam(NO 2 ) 2 ](PtC1 6 ) 1/2 (C), and [Cocyclam(NCS) 2 ](PtC1 6 ) 1/2 (D), were compared [195, 208]. The most consistent 42

74 variations were found in the cm -1 region. Complexes with a trans- configuration exhibited two bands at around 900 cm -1 and one band at around 810 cm -1, while those with a cis- configuration showed at least five evenly spread bands between 800 and 910 cm -1. These spectra are shown in Figure Figure 2.35 Infrared spectra of some cobalt(iii) complexes showing difference between cis- and trans-isomer [201] However, no reports were found for Co-cyclam coordination complexes comprising carboxylate ions as counterions. 2.8 Dinuclear cobalt carboxylate metallomesogens There are no reports found in the literature for dinuclear cobalt tetracarboxylates exhibiting mesogenic properties. 43

75 2.9 Mononuclear cobalt carboxylate cyclam metallomesogens Macrocyclic complexes of cobalt with tetrakis(4-n-alkyloxyphenyl)porphyrin (Figure 2.36) investigated by Kugimiya and Takemura [209]. These complexes formed mesophases in a wide range of temperature (from 45.3 to C). The complex showed two mesophases, both characterized as discotic lamellar phase by X-ray diffraction. In this phase, the disc-like molecules were stacked with their short molecular axes perpendicular or at some angle with respect to the layer normal, developing a smectic type organization. On cooling from the isotropic liquid phase at high temperature, the D L phase was observed where there was no positional order within the layer, while at low temperature, D Lʹ phase was observed where the molecules piled into columns and these columns were organized into layers (D L = discotic lamellar phase). R R N N Co N N R R Figure 2.36 Cobalt complex of 5,10,15,20-tetrakis(decyloxyphenyl)porphyrin; R = OC 10 H 21 [209] 2.10 Manganese carboxylates Structures and properties Common oxidation states of manganese are +2, +3, +4, +6, and +7. The most stable one is +2. Hence, most Mn(II) compounds are almost colorless or pale (pink) because of the forbidden spin-spin transition [210]. In addition, for compounds such as manganese(iii) acetate, the +3 oxidation state is quite common. Solid compounds of manganese(iii) 44

76 prefer distorted octahedral coordination due to the Jahn-Teller effect and they are of strong purple-red color. However, these compounds are powerful oxidizing agents and exhibit redox properties in solution (to manganese(ii) and manganese(iv)), and of great interest due to their magnetic properties [211]. Most Mn(II) carboxylates are dinuclear complexes showing either only carboxylate bridges (one [ ] or two [ ]), as well as other bridging ligands such as aqua [ ], hydroxo [228], phenoxo [ ], and alcoxo [235]. The coordination mode syn anti µ 1,3 -bridging mode is the most common one for dinuclear Mn(II) carboxylates with just two carboxylate bridges (Figure 2.37). Although this type of compound is comparatively abundant [ ], many were not magnetically characterized [ ]. The corresponding compounds consisting of monodentate carboxylate ligands in a bridging mode (µ 1, 1 ) (Figure 2.37) are not common. However, this binding mode are frequently observed in some 1D Mn(II) systems [ ]. Figure 2.37 Carboxylate binding modes involved in dinuclear Mn(II) compounds with two carboxylate bridges An example of a complex with only two carboxylate syn-anti binding mode is [Mn 2 (µ-phcoo) 2 (bpy) 4 ].(ClO 4 ) 2, reported by Albela et al. [246]. It was prepared by mixing [Mn(PhCOO) 2 ].nh 2 O and NaClO 4.H 2 O in absolute ethanol, followed by the addition of 2, 2ʹ-bipyridine. Its molecular structure (Figure 2.38) showed that the manganese ions were bridged by two benzoate groups. There was a crystallographic centre of inversion that related both halves of the dinuclear unit. In addition, there were 45

77 disordered perchlorate anions. Six-coordination on each manganese ion was accomplished by two chelating bpy groups and the geometry at each metal center was distorted octahedral. The Mn-O carboxylate bond lengths (~ Å) were shorter than Mn-N distances (~2.273 Å). Further, the distances from the N trans to the O carboxylate were slightly larger (2.279, Å) than those from the N cis to the O carboxylate (2.258, Å), possibly caused by the shorter Mn-O distances. The nonbonding Mn Mn distance was Å, similar to Mn Mn distances found in analogous complexes, such as [Mn 2 (µ-mecoo) 2 (bpy) 4 ](ClO 4 ) 2 (4.583 Å) [ ], [Mn 2 (µ-mecoo) 2 (L) 2 ](ClO 4 ) 2, L = N,Nʹ-dimethyl-N,Nʹ-bis(2-pyridylmethyl)ethane- 1,2-diamine (4.298 Å) [246], and [Mn 2 (µ-mecoo) 2 (tpa) 2 ](TCNQ) 2.2MeCN, tpa = tris(2-pyridylmethyl)-amine, TCNQ = tetracyanoquinodimethane (4.145 Å) [243]. Figure 2.38 Drawing of the cation [Mn 2 (µ-phcoo) 2 (bpy) 4 ] 2+ showing the syn-anti conformation of the carboxylate bridges [246] The variable temperature magnetic susceptibility data for the above complex showed that the room temperature χ M value of 0.04 cm 3 mol -1 K increased on cooling, reached a maximum of χ M cm 3 mol -1 at 4-5 K, and finally decreased, tending to zero at 0 K. This is typical for weak antiferromagnetic coupling between two Mn(II) ions. The g value (~ 2.0) agreed with the presence of manganese(ii) ions that do not exhibit spin-orbit coupling. In general the carboxylates are supposed to be ineffective in transmitting the exchange interaction [225, 253]. Accordingly, this complex exhibited small negative exchange coupling constants (J = cm -1 ), 46

78 consistent with the great distance between the two manganese ions. The J values reported in the literature for analogous complexes are always weak (-0.2 to -5 cm -1 ) [ ]. Another complex, [{Mn(phen) 2 } 2 (m-clc 6 H 4 COO) 2 ](ClO 4 ) 2, crystallized in the triclinic space group P-1, as reported in 2010 by Gómez et al. [211]. Its crystal structure is depicted in Figure The hexacoordination of each manganese ion was accomplished by two phen ligands, leading to a distorted octahedral geometry around Mn(II) ions, with Mn Mn distance of ~ 4.72Å, and Mn O distances much shorter than Mn N distances (av and Å). These distances were consistent with those reported for analogous compounds [ ]. There were π-stacking between phen ligands of neighboring molecules, forming chains which were interconnected through ClO - 4 anions and CH 3 CN molecules by hydrogen bonds, and produced a 3D system (Figure 2.40). Figure 2.39 Crystal structures of the cationic complex of [{Mn(phen) 2 } 2 (m-clc 6 H 4 COO) 2 ](ClO 4 ) 2 [211] 47

79 Figure 2.40 π-stacking between phen ligands of dinuclear units of [{Mn(phen) 2 } 2 (m-clc 6 H 4 COO) 2 ](ClO 4 ) 2 generating chains [211] The FTIR spectrum of the above complex showed two strong bands at ~ 1603 and ~ 1403 cm -1, assigned to the asymmetric and symmetric vibrations from the carboxylate groups. The value of Δ [ν asym (COO) ν sym (COO) of ~ 200 cm -1 ] indicated bridging bidentante (µ 1,3 ) carboxylate ligands [79]. Broad bands at ~1100 cm -1 and a medium intensity band at 623 cm -1 were assigned to the perchlorate ions. Characteristic bands for the phen ligand were observed at 1518, 1427, 865, 850 and 723 cm -1. Its χ M T vs T and χ M vs T plots are shown in Figure The χ M T value was 9.21 cm 3 mol -1 K at 300 K, which was in agreement with the characteristic value for two uncoupled Mn(II) ions (S = 5/2, 8.75 cm 3 mol -1 K assuming g = 2). With decreasing temperature, the χ M T values decreased until reaching 0.92 cm 3 mol -1 K at 2 K, indicated an antiferromagnetic coupling. Analogous behavior was observed in the χ M vs T plots (inset Figure 2.41). The J value (-1.41 cm -1 ) agreed with the range ~ 0 to cm -1 found for Mn(II) compounds in the literature with two syn anti carboxylate bridges [ ]. 48

80 Figure 2.41 χ M T vs T and χ M vs T (inset) plots for [{Mn(phen) 2 } 2 (m-clc 6 H 4 COO) 2 ](ClO 4 ) 2 ( ). The solid line is the best fit to the experimental data [211] An example of oxo bridged dinuclear metal carboxylate complexes is - [Mn 2 (µ-o)(µ-mecoo) 2 {HB(pz) 3 } 2 ], where HB(pz) 3 = hydrotris(1-pyrazolyl)borate, as reported by Sheats et al. [259]. In this complex, two six-coordinated manganese centres were bridged by an oxo and two acetate groups. The remaining coordination sites were - occupied by two tridentate HB(pz) 3 ligands (Figure 2.42). Figure 2.42 One oxo and two acetate bridged manganese complex [259] The FTIR data for the above complex suggested a bridging bidentate MeCOO ligand with Δ = 148 cm -1 (Δ = cm -1 ). Usually, complexes of Mn(III) absorbs 49

81 in the vicinity of 500 nm with extinction coefficients close to 300 M -1 cm -1 [260]. The absorption spectra of this complex in CH 2 C1 2 showed a broad band at 486 nm (ε max = 210 M -1 cm -1 ) in accordance with values reported in the literature. The above authors also studied the temperature-dependence of molar susceptibilities and effective magnetic moments per Mn for this complex (Figure 2.43). Both sets of results were in agreement with two isolated high spin Mn(III) sites with -l weak antiferromagnetic exchange coupling between them. The χ M vs T plots for the sample increased almost linearly with temperature. The magnetic moment dropped slightly from 4.96 BM to 4.88 BM per Mn between 300 and 15.7 K, and further dropped -l to 4.61 BM at 5.4 K. Fitting the χ M vs T data to the expression derived from the spin exchange Hamiltonian Ĥ = -2JS1.S2 for S1 = S2 = 2 [261] revealed J values ~ to cm -1. -l Figure 2.43 Plots of χ M and μ eff vs T of [Mn 2 (µ-o)(µ-mecoo) 2 {HB(pz) 3 } 2 ] [259] Yu and Lippard [262] reported an aqua-bridged complex, [Mn 2 (H 2 O)(Piv) 4 (Me 2 Bpy) 2 (Figure 2.44), obtained as yellow crystals. It was synthesized by stiring a mixture of Mn(piv) 2 in MeOH and 4,4'-Me 2 -Bpy for 2 hr. Its single crystal X-ray data showed that two Mn(II) atoms were bridged by a water molecule and two bidentate carboxylate ligands. Each of the Mn atoms has an one 50

82 additional monodentate carboxylate ligand. The noncoordinating oxygen atoms on each carboxylates were strongly hydrogen bonded to the bridging water molecule, as suggested by the short O1 O2 and O1 O4 distances. As a result, the O-H stretching frequency was shifted to 1965 cm -1. The coordination sphere around each manganous ion was accomplished by two N atoms from the terminal bidentate nitrogen donor ligands. The Mn Mn distance was Å. Figure 2.44 ORTEP drawing of [Mn 2 (H 2 O)(Piv) 4 (Me 2 Bpy) 2 [262] The variable-temperature (2-300 K) magnetic susceptibility measurements for the above complex showed a decrease in effective moments from to BM/molecule with decreasing temperature (J = -2.73(2) cm -1, g = 1.939(3)). The small negative exchange coupling constant is in accord with the long distances between the two manganese sites and also with the concept that antiferromagnetic coupling between two metal ions depends on the bridging ligands with ljl values following the order O 2- > OH - > H 2 O [225] Manganese Carboxylate-Cyclam Complexes Mn(III)-cyclam complexes have been reported earlier by Poon [263] and by Brian [264], who also studied room temperature magnetic properties of the complexes in order to establish their formulation as high spin d 4 Mn(III) system. No definitive structural 51

83 study has appeared, but the cyclam complexes of general type [Mn(cyclam)X 2 ]Y (where X and Y are anionic species) have been formulated as trans-octahedral system. Later, numerous studies on structural properties and variable temperature magnetic properties of such complexes were reported [ ]. However, no Mn(III)-cyclam complex comprising carboxylates as counter ions are yet to be reported Dinuclear manganese carboxylate metallomesogens There are no reports found in the literature for metallomesogenic binuclear carboxylates Mn(II) complexes Mononuclear manganese carboxylate-cyclam metallomesogens Macrocyclic complexes of manganese with 5,10,15,20-tetrakis(4-n-dodecylphenyl) porphyrin (C 12 TPPMnCl) and its tetracyanoquinodimethane (C 12 TPPMn.TCNQ) derivatives (Figure 2.45) [270] and with octaalkoxymethyl-phthalocyanines [5], have been found to exhibit discotic lamellar and discotic Col h mesophses, respectively. Hill et al. [270] summarized their DSC results as follows: C 12 TPPMnCl: Cr [13 C (var), 16 kj mol -1 ] D L [92.2 C, 8.5 kj mol -1 ] Iso. C 12 TPPMn.TCNQ: Cr 1 [80.2 C, 53.7 kj mol -1 ] Cr 2 [183 C, 1.3 kj mol -1 ] D x [220.5 C, 56.l kj mol -1 ] Iso. R R N N Mn N X N R R Figure 2.45 Manganese complex of 5,10,15,20-tetrakis(4-n-dodecylphenyl)porphyrin; R = C 12 H 25 ; X = Cl -, TCNQ - (tetracyanoquinodimethane) [270] 52

84 CHAPTER 3: EXPERIMENTAL 3.1 Introduction The aim of this research was to synthesise and characterize the magnetic metallomesogens of general formulas [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO), [Cu(cyclam) (H 2 O) 2 ](4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2 and [M(cyclam)](4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2, where X = F, Cl, Br, I, NO 2 ; L = 4-hexadecyloxypyridine; cyclam = 1,4,8,11- tetraazacyclotetradecane; M = Ni(II), Co(II) and Mn(II) and n = 9, 11, 13, 15. The total number of complexes was 21. The structural formulas of all ligands are shown in Figure 3.1. CH 3 (CH 2 ) n O COO - NH NH HN HN N OCH 2 (CH 2 ) 14 CH 3 (a) (b) (c) Figure 3.1 The structural formula of the ligands: (a) 4-n-alkyloxybenzoate ion (n = 9, 11, 13, and 15); (b) 1,4,8,11-tetraazacyclotetradecane (cyclam); and (c) 4-hexadecyloxypyridine (L) The ligands were characterized by 1 H-nuclear magnetic resonance spectroscopy ( 1 H-NMR) and FTIR spectroscopy, while the complexes were characterized by CHN elemental analyses, X-ray crystallography (for crystals), FTIR spectroscopy, UV-vis spectroscopy, room-temperature magnetic susceptometry by the Gouy method, thermogravimetry (TGA), differential scanning calorimetry (DSC), and polarizing optical microscopy (POM). 3.2 Materials All chemicals were analar reagents and used as received. The list of the chemicals used is given in Table

85 Table 3.1 The chemicals used in this research, arranged in alphabetical order Name Chemical formula Formula weight (gmol -1 ) 1-Bromodecane CH 3 (CH 2 ) 9 Br Bromododecane CH 3 (CH 2 ) 11 Br Bromotetradecane CH 3 (CH 2 ) 13 Br Bromohexadecane CH 3 (CH 2 ) 15 Br Copper(II) sulfate pentahydrate CuSO 4.5H 2 O Cobalt(II) chloride hexahydrate CoCl 2.6H 2 O Ethyl 4-hydroxybenzoate 4-HOC 6 H 4 COOC 2 H Hydroxypyridine 4-OHC 5 H 4 N 95.1 Manganese(II) chloride tetrahydrate MnCl 2.4H 2 O Nickel(II) chloride hexahydrate NiCl 2.6H 2 O ,4,8,11-Tetrazacyclotetradecane C 10 H 24 N [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO) 2 (X = F, Cl, Br, I, and NO 2 ) The precursor complexes, [Cu 2 (4-XC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ].nh 2 O (X = F, n = 2; X = Cl, Br, I, n = 0), [Cu 2 (4-NO 2 C 6 H 4 COO) 4 (CH 3 CH 2 OH)(H 2 O)], and [Cu 2 (3,5-(NO 2 ) 2 C 6 H 3 COO) 4 (H 2 O) 2 ] were obtained from Mohamadin [271] Synthesis of 4-hexadecyloxypyridine (L) 1-Bromohexadecane (15.3 g, 50.8 mmol) was added portion wise to a vigorously stirred mixture of 4-hydroxypyridine (5.01 g, 52.7 mmol), K 2 CO 3 (125.2 mmol, 17.3 g) and KI (0.33 g, 2.0 mmol) in DMF (200 cm 3 ) at room temperature. The mixture was refluxed for 24 h, cooled to room temperature, and poured into distilled water. The pale yellow solid obtained was washed several times with distilled water, purified using hot ethanol, and dried in an oven at 60 C. The yield was 88.8% [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) An ethanolic solution of cyclam (0.12 g, 1.0 mmol) was added portion wise to a hot ethanolic suspension of [Cu 2 (4-FC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ].2H 2 O (0.28 g, 0.3 mmol). 54

86 The purple solution formed was heated for 1 h and filtered hot. [Cu(cyclam)(H 2 O) 2 ] (4-FC 6 H 4 COO) 2.2H 2 O was isolated as purple-needle shaped crystals (0.26 g, 61.9%). An ethanolic solution of [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (0.37 g, 0.6 mmol) and L (0.37 g, 1.2 mmol) was gently heated for 10 min, filtered while still hot, and left to cool to room temperature. [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) was formed as dark-purple powder (0.5 g, 68.5%) [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) The procedure was the same as for [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Section 3.3.2), using cyclam (0.30 g, 1.6 mmol), [Cu 2 (4-ClC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ] (0.70 g, 0.8 mmol), [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (0.39 g, 0.6 mmol) and L (1.2 mmol, 0.37 g). The product was a dark-purple powder (0.5 g, 66.7%). The yield of [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O was 0.70 g (64.8%), and [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) was 0.5 g (66.7%) [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) The procedure was the same as for [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Section 3.3.2), using cyclam (0.08 g, 0.4 mmol), [Cu 2 (4-BrC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ] (0.18 g, 0.2 mmol), [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (0.45 g, 0.61 mmol) and L (0.37 g, 1.2 mmol). The yield of [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O was 0.15 g (57.7%) and [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) was 0.5 g (61.0%) [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) The procedure was the same as for [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Section 3.3.2), using cyclam (0.06 g, 0.32 mmol), [Cu 2 (4-IC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ] (0.19 g, 0.16 mmol), [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (0.5 g, 0.6mmol) and L (0.37 g, 1.2 mmol). The yield of [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2.2H 2 O was 0.18 g (69.2%) and [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) was 0.55 g (64.0%). 55

87 3.3.6 [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) The procedure was the same as for [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Section 3.3.2), using cyclam (0.20 g, 1.0 mmol), [Cu 2 (4-NO 2 C 6 H 4 COO) 4 (CH 3 CH 2 OH)(H 2 O)] (0.47 g, 0.5 mmol), [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (0.42 g, 0.6 mmol), and L (0.37 g, 1.2 mmol). The yield of [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O was 0.52 g (68.4%, purple needles) and [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2 (5) was 0.45 g (60.8%) [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] The procedure was the same as for [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Section 3.3.2), using cyclam (0.08 g, 0.4 mmol) and [Cu 2 (3,5-(NO 2 ) 2 C 6 H 3 COO) 4 (H 2 O) 2 ] (0.26 g, 0.2 mmol). [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] was isolated as black block crystals (0.29 g, 63.0%). The complex did not react with L. 3.4 [M(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2.2H 2 O; (M = Cu(II), Ni(II), Co(II), and Mn(II); n = 9, 11, 13 and 15) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (6) A solution of 4-HOC 6 H 4 COOC 2 H 5 (8.31 g, 50.0 mmol) and CH 3 (CH 2 ) 9 Br (15.3 g, 50.0 mmol) in DMF was heated under reflux in the presence of K 2 CO 3 (in excess) and KI (0.33 g, 2.0 mmol) for 24 h. The reaction mixture was cooled to room temperature, and the 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H 5 (white solid) formed was filtered, washed thoroughly with distilled water, and purified using hot ethanol. Yield: 13.6 g (88.6%). An aqueous solution of KOH (in excess) was added portionwise to a hot solution of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H 5 (6.63 g, 20.0 mmol) in C 2 H 5 OH (200 cm 3 ). The mixture was heated under reflux for 4 h, cooled to room temperature, and the 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK (white powder) formed was filtered, washed thoroughly with distilled water and dried in a warm oven. Yield: 5.0 g (79.1%). 56

88 An aqueous solution of CuSO 4.5H 2 O (1.01 g, 4.0 mmol) was added portionwise to a hot solution of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK (2.6 g, 8.0 mmol) in C 2 H 5 OH (100 cm 3 ) and the mixture heated at 60 o C for 30 min. [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was formed as blue powder, filtered hot, washed with ethanol, and dried in a warm oven. Yield: 1.41 g (52.4%). The final procedure was the same as for [Cu(cyclam)(H 2 O) 2 ] (4-FC 6 H 4 COO) 2.2H 2 O described in (Section 3.3.2), using cyclam (0.4 g, 2.0 mmol) and [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (1.31 g, 1.0 mmol). The product [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O was isolated as purple plate crystals (1.01 g, 56.7%) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2.2H 2 O (7) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-HOC 6 H 4 COOC 2 H 5 (8.32 g, 50.0 mmol), CH 3 (CH 2 ) 11 Br (12.0 g, 50 mmol), KI (0.34 g, 2 mmol), 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H 5 (6.64 g, 20.0 mmol), CuSO 4.5H 2 O (1.24 g, 5.0 mmol), 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOK (4.12 g, 10.0 mmol), cyclam (0.4 g, 2.0 mmol), and [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (1.64 g, 1.0 mmol). The yield of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H 5 was 14.6 g (87.2%), 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOK was 4.78g (69.3%), [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was 2.78g (67.1%), and [Cu(cyclam) (H 2 O) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2.2H 2 O was 1.32 g (58.9%, purple plates) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 2H 2 O (8) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-HOC 6 H 4 COOC 2 H 5 (8.31 g, 50.0 mmol), CH 3 (CH 2 ) 13 Br (13.6 g, 50.0 mmol), KI (0.36 g, 2.0 mmol), 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H 5 (6.17g, 17.0 mmol), CuSO 4.5H 2 O (1.25g, 5.0 mmol), 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOK (4.10g, 10.0mmol), cyclam (0.06 g, 0.3mmol), and [Cu 2 (4-CH 3 (CH 2 ) 13 57

89 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (0.27 g, 0.15 mmol). The yield of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H 5 was 16.1 g (87.8%), 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOK was 5.40 g (84.4%), [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was 2.51 g (59.5%), and [Cu(cyclam) (H 2 O) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2.2H 2 O was 0.22 g (62.9%, purple needles) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O (9) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-HOC 6 H 4 COOC 2 H 5 (8.32 g, 50.0 mmol), CH 3 (CH 2 ) 15 Br (15.3 g, 50.0 mmol), KI (0.33 g, 2.0 mmol), 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H 5 (5.61 g, 14 mmol), CuSO 4.5H 2 O (1.26 g, 5.0 mmol), 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOK (4.02 g, 10.0 mmol), cyclam (0.40 g, 2.0 mmol) and [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (1.64 g, 1.0 mmol). The yield of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H 5 was 16.6 g (84.9%), 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOK was 4.15 g (74.1%), [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was 2.52 g (61.0%), and [Cu(cyclam) (H 2 O) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O was 1.3 g (61.6%, purple prisms) [Ni(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (10) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK (1.24 g, 4.0 mmol), NiCl 2.6H 2 O (0.48 g, 2.0 mmol), cyclam (0.01 g, 0.05 mmol), and [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (0.04 g, 0.03 mmol). The yield of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] was 0.73 g (56.6%, pale green powder), and [Ni(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O was 0.03 g (60.0%, purple needles) [Ni(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (11) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOK (3.14 g, 9.0 mmol), NiCl 2.6H 2 O (1.19 g, 5.0 mmol), cyclam (0.01 g, 0.05 mmol), and 58

90 [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] (0.04 g, 0.03 mmol). The yield of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] was 1.77 g (54.1%), and [Ni(cyclam) (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O was 0.03 g (60.0%, purple needles) [Ni(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O (12) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOK (4.06 g, 10.0 mmol), NiCl 2.6H 2 O (1.19 g, 5.0 mmol), cyclam (0.04 g, 2.0 mmol), and [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O (0.20 g, 1.0 mmol). The yield of [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O was 2.19 g (51.5%), and [Ni(cyclam) (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O was 0.13 g (54.2%, purple needles) [Ni(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O (13) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOK (3.01 g, 8.0 mmol), NiCl 2.6H 2 O (0.95 g, 4.0 mmol), cyclam (0.02 g, 0.08 mmol), and [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (0.06 g, 0.04 mmol). The yield of [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O was 2.13 g (68.1%), and [Ni(cyclam) (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O was 0.05 g (71.4%, purple powder) [Co(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (14) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK (1.39 g, 4.0 mmol), CoCl 2.6H 2 O (0.48 g, 2.0 mmol), cyclam (0.02 g, 0.12 mmol) and [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (0.09 g, 0.06 mmol). The yield of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] was 0.77 g (53.1%), and [Co(cyclam) (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O was 0.08 g (72.7%, dark red powder). 59

91 [Co(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (15) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOK (3.01 g, 9.0 mmol), CoCl 2.6H 2 O (1.19 g, 5.0 mmol), cyclam (0.04 g, 0.2 mmol) and [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] (0.2 g, 0.1 mmol). The yield of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] was 1.77 g (56.7%), and [Co(cyclam) (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O was 0.15 g (60.0%, dark red powder) [Co(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O (16) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOK (4.04 g, 10.0 mmol), CoCl 2.6H 2 O (1.19 g, 5.0 mmol), cyclam (0.04 g 0.2 mmol), and [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] (0.2 g, 0.1 mmol). The yield of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] was 2.23 g (53.3%), and [Co(cyclam) (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O was 0.15 g (60.0%, dark red powder) [Co(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O (17) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOK (3.32g, 8.0 mmol), CoCl 2.6H 2 O (0.95 g, 4.0 mmol), cyclam (0.04 g, 0.2 mmol) and [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O (0.18 g, 0.1 mmol). The yield of [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O was 2.07 g (59.1%), and [Co(cyclam) (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O was 0.14 g (66.0%, dark red powder) [Mn(cyclam)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK (1.21 g, 4.0 mmol), MnCl 2.4H 2 O (0.40 g, 2.0 mmol), cyclam (0.02 g, 0.1 mmol) and 60

92 [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (0.06 g, 0.05 mmol). The yield of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O was 0.77 g (61.6%), and [Mn(cyclam) (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO).2H 2 O was 0.06 g (60.0%, green flakes) [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOK (3.08 g, 9.0 mmol), MnCl 2.4H 2 O (0.99 g, 5.0 mmol), cyclam (0.02 g, 0.12 mmol), and [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (0.08 g, 0.06 mmol). The yield of [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O was 1.81 g (56.9%), and [Mn(cyclam) (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO).2H 2 O was 0.07 g (61.5%, green flakes) [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOK (4.05 g, 10.0 mmol), MnCl 2.4H 2 O (0.99 g, 5.0 mmol), cyclam (0.02 g, 0.12 mmol) and [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] (0.09 g, 0.06 mmol). The yield of [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] was 2.30 g (55.8%), and [Mn(cyclam) (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO).2H 2 O was 0.09 g (60.0%, green flakes) [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) The procedure was the same as for [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (Section 3.4.1), using 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOK (3.08g, 8.0 mmol), MnCl 2.4H 2 O (0.79 g, 4.0 mmol), cyclam (0.03 g, 0.16 mmol) and [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (0.13 g, 0.08 mmol). The yield of 61

93 [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O was 2.02 g (63.9%), and [Mn(cyclam) (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO).2H 2 O was 0.15 g (68.2%, green powder). 3.5 Instrumental Analyses H-Nuclear magnetic resonance spectroscopy The 1 H-NMR was recorded on a JEOL FT-NMR lambda 400 MHz spectrometer. A small amount of the sample was dissolved in CDCl 3. The chemical shifts were reported in ppm, using the residual protonated solvent as the reference Elemental analyses Elemental analyses were performed on a Perkin-Elmer CHNS/O 2400 Series II elemental analyser. The sample (1-2 mg) was weighed on an AD-6 microbalance, wrapped in a thin aluminium capsule (5 x 8 mm) and folded firmly in smaller size to fit in the column. Then it was placed into the analyzer and heated to a maximum temperature of 1000 C X-ray crystallography Intensity data were collected at reduced temperature on a Bruker SMART APEX II CCD fitted with Mo Kα radiation so that max was 27.5, 28.3 and 27.5, respectively. Each data set was corrected for absorption based on multiple scans [272] and reduced using standard methods [273]. The structures were solved by direct methods with SHELXS97 [274] and refined by a full-matrix least-squares procedure on F 2 using SHELXL97 with anisotropic displacement parameters for non-hydrogen atoms and a weighting scheme of the form: w = 1/[σ 2 (F 2 o ) + ap 2 + bp], where P = (F 2 o + 2F 2 c )/3). All hydrogen atoms were refined isotropically in their idealized positions except for water-bound H atoms where they were located in the difference map and were then fixed as in their found positions. No absorption corrections were done. The molecular 62

94 structures were drawn with 50% or 70% displacement ellipsoids using Mercury [275] and the packing diagrams were drawn with the DIAMOND program [276] Fourier transform infrared spectroscopy The FTIR spectra were recorded in the cm -1 region on a Perkin-Elmer Spectrum 400 FT-IR/FTR/Pike Technologies Cladi ATARTM. A minute amount of the neat sample was placed in the diamond hole, the detector was allowed to touch the sample surface and the spectrum was recorded UV-visible spectroscopy The spectra were recorded on a SHIMADZU UV-vis-NIR 1600 spectrophotometer in the wavelength range of 300 nm to 2000 nm. The sample was dissolved in a suitable solvent in a 10- ml volumetric flask, and the solution was introduced in a 1 cm quartz cuvette. The spectrum was recorded against the solvent as a background Magnetic susceptibility The gram magnetic susceptibility (χ g ) was measured at room-temperature (298 K) on a Sherwood Auto Magnetic susceptibility balance by the Gouymethod. Distilled water (0.72 x 10-6 c.g.s) was used as the calibrant. The finely grinded sample was filled into a narrow cylindrical tube to a length of about 1.5 cm, and the weight of the sample was recorded. The tube was placed into the instrument and the χ g value was noted from the instrument. Then the diamagnetic contribution χ dia, of each atom in the molecule was calculated from the Pascal s constant [277] and the molar susceptibility, χ m, was obtained by multiplying the value of χ g with molecular weight. The value of χ corr M was calculated from the relationship: χ M corr = χ m χ dia. Finally the effective magnetic moment (μ eff ) was calculated using the following equation: where T is the temperature in kelvin (K) μ eff = 2.828(χ M corr T) ½ 63

95 3.5.7 Thermogravimetry The TGA was recorded on a Perkin-Elmer 4000 TG/DTA Thermal System. A ceramic pan was placed on the holder, covered and tared. The sample (2-5 mg) was introduced into the pan, placed on holder and heated at a temperature range of 35 C to 900 C at the scan rate 20 C min -1. The analyses were done under N 2 at a flow rate of 10 cm 3 min Differential scanning calorimetry The differential scanning calorimetry(dsc) was done on a METTLER TOLEDO DSC822 and on a Perkin-Elmer DSC6. The sample (2-8 mg) was introduced on an aluminum crucible, weighed on a microbalance, and placed in the DSC heating stage. The crucibles were then subjected to four successive heating and cooling cycles in suitable temperature range ( C) and the scan rate was 10 C min -1. The analysis was done under N 2 gas at a flow rate of 10 cm 3 min Polarizing optical microscopy The photomicrographs were captured on an Olympus polarizing microscope equipped with a Mettler Toledo FP90 central processor and a Linkam THMS 600 hot stage. The sample was finely ground and dried in an oven at 60 o C overnight prior to analysis. The heating and cooling rates were varied between 2 and 10 o C min -1, and the magnification was 50x. 64

96 CHAPTER 4: RESULTS AND DISCUSSION 4.1 Introduction The objective of this research was to synthesise and characterize magnetic metallomesogens of general formulas [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO) 2, [Cu(cyclam)(H 2 O) 2 ](R) 2, [M(cyclam)(R) 2 ] 2H 2 O, and [Mn(cyclam)(R) 2 ]R.2H 2 O where cyclam = 1,4,8,11-tetraazacyclotetradecane; X = F, Cl, Br, I, NO 2 ; L = 4-hexadecyloxypyridine; M = Ni(II), Co(II); R = 4-CH 3 (CH 2 ) n OC 6 H 4 COO; and n = 9, 11, 13, 15. The total number of complexes was [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO) [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2 2H 2 O a) Synthesis and structural elucidation of 4-hexadecyloxypyridine (L) 4-Hexadecyloxypyridine (L) was obtained as a pale brown powder from the reaction of 1-bromohexadecane and 4-hydroxypyridine in the presence of K 2 CO 3 and KI in DMF. The yield was 88.8%. Its 1 H-NMR spectrum (Figure 4.1) showed a multiplet at 7.26 ppm and a quartet at 6.39 ppm for the aromatic protons (H1, H2), a triplet at 3.75 ppm for two methylene protons (CH 3 (CH 2 ) 14 CH 2 O-) labelled as H3, a multiplet at 1.25 ppm for twenty eight methylene protons (CH 3 (CH 2 ) 14 CH 2 O-) labelled as H4, and a triplet at 0.88 ppm for three methyl protons (CH 3 (CH 2 ) 14 CH 2 O-) labelled as H5. Its FTIR spectrum (Figure 4.2) showed two strong bands at 2919 cm -1 and 2851 cm -1 for ν asym CH 2 and ν sym CH 2, respectively, a medium band at 1638 cm -1 for C=N stretching frequency of pyridine moiety in L, a medium band at 1287 cm -1 for C-N stretching frequency of pyridine moiety, and a strong band at 1188 cm -1 for C-O stretching frequency of ether moiety. Hence, both spectral data support the structure of L shown in Figure

97 H4 H1 H2 H3 H5 Figure H-NMR spectrum of 4-hexadecyloxypyridine (L) T% cm -1 Figure 4.2 IR spectrum of 4-hexadecyloxypyridine (L) 66

98 b) Synthesis and structural elucidation of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) was prepared from the reaction of [Cu 2 (4-FC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ].2H 2 O with cyclam in ethanol, followed by L (Scheme 4.1). [Cu 2 (4-FC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ].2H 2 O + cyclam Ethanol,30 min [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O L [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O Scheme 4.1 Syntheses of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O was obtained as purple-needleshaped crystals and the yield was 61.9%. Its chemical formula, based on the results of elemental analyses is C 24 H 40 CuF 2 N 4 O 8 (FW= g mol -1 ; Calc.: C, 46.9; H, 6.6; N, 9.1%. Found: C, 46.9; H, 6.7; N, 9.9%). [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O crystallized in the triclinic system with the space group P -1. Crystal data and refinement details are given in Table 1 (APPENDIX A) and selected bond lengths and angles are given in Table 4 (APPENDIX A). Its single crystal X-ray crystallography revealed that the Cu atom (Figure 4.3a) was located on a crystallographic centre of inversion and existed within a trans-n 4 O 2 donor set, being tetra-coordinated by the four aza-n atoms of cyclam [Cu N1 = 2.031(2) Å, Cu N2 = 2.003(2) Å and Cu O1 = 2.387(2) Å] and two trans-o atoms derived from coordinated aqua ligands. The 4-fluorocarboxylato ligands were associated with the complex cation by aqua-o-h...o1 and aqua-o-h...o4 hydrogen bonds. The resulting coordination geometry was based on a distorted octahedron. The O3 atom was aligned over the Cu N4 bond but was orientated away from the Cu atom to allow for the formation of N4 H O hydrogen bond with lattice 67

99 H 2 O. The relatively long Cu1-O1W distance (2.387(2) Å) compared to Cu1-N1 (2.031(2) Å) and Cu1-N2 (2.003(2) Å), was a consequence of the Jahn-Teller distortion that caused the cationic complex to exhibit axial elongation. The components of the crystallographic asymmetric unit were connected via O H...O hydrogen bonds whereby coordinated and lattice H 2 O molecules bridged the carboxylate-o atoms. One of the amine-n H atoms formed a N H...O hydrogen bond to a carboxylate-o atom and another one to an O atom of lattice H 2 O (Table 4.1). As the complex cations each laid down on a centre of inversion, similar hydrogen bonds formed on the other side of each CuN 4 plane leading to a supramolecular chain (Figure 4.3b). Table 4.1 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (R = 4-FC 6 H 4 COO) [Å and ] D-H...A d(d-h) d(h...a) d(d A) <(DHA) O1W-H1WA O (2) 1.835(2) 2.711(3) 174.6(2) O1W-H1WB O (2) 1.868(2) 2.737(3) 168.9(2) O3W-H3WA O (2) 1.902(2) 2.736(3) 166.8(2) N3-H3 O (3) 2.015(2) 2.909(4) 160.6(2) N4-H4 O3W 0.930(3) 2.073(2) 2.969(4) 161.3(2) 68

100 (a) (b) Figure 4.3 (a) Molecular view of [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O showing displacement ellipsoids at 50% probability level, (b) supramolecular chain; most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity. The O H O and N H O hydrogen bonds, shown as blue and green dashed lines respectively, lead to a chain. Colour code: Cu, light blue; O, red; N, blue; C, grey; and F, green 69

101 Its FTIR spectrum (Figure 4.4) and the corresponding data (Table 4.2, which also contains the data for complex 1 for later discussion), showed one broad band at 3342 cm -1 for O-H stretching of H 2 O, one broad band at 3200 for N-H stretching of secondary amine, a medium band at 1548 cm -1 and a strong band at 1374 cm -1 for ν asym COO and ν sym COO stretching, respectively, and a medium band at 1095 cm -1 for C-N stretching. The COO (ν asym COO - ν sym COO) value was 174 cm -1, is in agreement with non coordinated 4-FC 6 H 4 COO - ions [ ], as revealed from its crystal structure T% cm Figure 4.4 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O Table 4.2 FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (1) (R = 4-FC 6 H 4 COO) Complex Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-O C-N [Cu(cyclam)(H 2 O) 2 ] (R) 2.2H 2 O 3342br 3200br m (asym) 1374s (sym) m br 3183br 2915s (asym) 1638m (asym) 1284s 1189m 2849s (sym) 1472s (sym) br, broad; s, strong; m, medium; w, weak. 70

102 abs Its UV-vis spectrum (Figure 4.5) in CHCl 3 showed a broad d-d band at 545 nm (ε max = 60.6 M -1 cm -1 ) suggesting a trans-iii octahedral geometry [282, 283]. This implies that the geometry observed in the molecular structure of the crystals was maintained in solution nm Figure 4.5 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O Its µ eff value, calculated from the values of FM = g mol -1, χ g = 2.6 x 10-6 cm 3 g -1, χ M = 1.6 x 10-3 cm 3 mol -1, and χ dia = -3.2 x 10-4 cm 3 mol -1, was 2.2 B.M. at 298 K. The value was in the range found for mononuclear Cu(II) complexes in a distorted octahedral geometry ( B.M.) [109, ]. [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O reacted with L to form [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1), obtained as a purple powder (Scheme 4.1), and its yield was 68.5%. Its chemical formula, based on the results of elemental analyses, is C 66 H 10 CuF 2 N 6 O 6 (FW= g mol -1 ; Calc.: C, 67.1; H, 9.1; N, 7.1%. Found: C, 67.6; H, 10.3; N, 6.0%). Its FTIR spectrum (Figure 4.6) showed a broad band at 3359 cm -1 for O-H stretching of H 2 O, one broad band at 3183 cm -1 for N-H stretching of pyridine moiety in ligand L, one strong band at 2915 cm -1 and one medium band at 2849 cm -1 for ν asym CH 2 and ν sym CH 2 stretching frequency, respectively, a medium band at 1638 cm -1 for C=N 71

103 abs stretching frequency of pyridine moiety in ligand L and for ν asym COO and a strong band at 1472 cm -1 for ν sym COO stretching frequency, respectively, a medium band at 1284 cm -1 for C-O stretching frequency of the ether moiety in ligand L, and a medium band at 1189 cm -1 for C-N stretching frequency of cyclam. The COO value was 166 cm -1, suggesting non coordinated 4-FC 6 H 4 COO - ions [ ] T% cm Figure 4.6 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) Its UV-vis spectrum (Figure 4.7) in CHCl 3 showed a broad d-d band at 547 nm (ε max = 89.9 M -1 cm -1 ) suggesting a trans-iii octahedral geometry [282, 283] as similarly suggested for [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O nm Figure 4.7 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) 72

104 Its µ eff value, calculated from the values of FM = g mol -1, χ g = 3.3 x 10-7 cm 3 g -1, χ M = 4.0 x 10-4 cm 3 mol -1, and χ dia = -7.8 x 10-4 cm 3 mol -1, was 1.7 B.M. at 298 K. This is in agreement with a mononuclear complex with octahedral geometry around Cu(II) (1.73 B.M.) [109]. However, the µ eff value was lower than that of [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2 (2.12 BM), and may be due to the effect of L. The alkyl group is an electron releasing group, making L a strong Lewis base. This resulted in a stronger Cu(II)-N axial bonds and a less distorted octahedral geometry at Cu(II). Combining the instrumental data discussed above, its proposed structural formula is shown in Figure 4.8. N N RO N Cu N OR F COO N N 2 Figure 4.8 Proposed structure of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) (R = C 16 H 33 ); lattice H 2 O is not shown c) Thermal behaviour Thermogravimetric analysis (TGA) was done to determine the thermal stability of complexes. The TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Figure 4.9) showed an initial weight loss of 6.0% from 74 o C to about 100 o C due to the evaporation of lattice H 2 O (expected 5.9%), followed by 6.0% from 161 o C to about 217 o C due to the evaporation of coordinated H 2 O (expected 5.9%), 72.0% from 240 o C to about 642 o C due to the decomposition of cyclam ligand and 4-FC 6 H 4 COO - ions (expected, 77.9%), leaving 16.0% residue at temperatures above 642 o C (expected, 10.3% assuming CuO) [66, 291, 292]. The result is in agreement with its chemical formula, and its decomposition temperature was 240 o C. 73

105 Weight (%) Temperature ( C) Figure 4.9 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O The TGA trace for 1 (Figure 4.10) showed an initial weight loss of 4.0% from 62 o C to about 153 o C due to the evaporation of lattice H 2 O molecules (expected, 3.0%). The next weight loss of 89.0% from 224 o C to about 726 o C due to the decomposition of cyclam and 4-hexadecyloxypyridine ligands and 4-FC 6 H 4 COO - ions (expected, 91.8%), leaving 7.0% residue at temperatures above 726 o C (expected, 5.2% assuming CuO) [66, 291, 292]. Hence, the result was in agreement with its chemical formula, and its decomposition temperature was 224 o C. Thus, this complex was less stable than [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2. 2H 2 O (T dec = 240 o C). As discussed earlier the equatorial Cu(II)-N bond was stronger that made the axial Cu(II)-N bond weaker. It resulted in lowering the decomposition temperature of 1 compared to [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2. 74

106 Weight (%) Temperature ( C) Figure 4.10 TGA trace for [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) d) Mesomorphic properties The mesomorphic properties of 1 were probed by DSC (for phase transitions) and POM (for optical textures). Its DSC was recorded in the temperature range C. The scan (Figure 4.11) showed two broad endothermic peaks at 42.3 C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition and at C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition on heating, and on cooling, a weak exothermic peak at 85.7 C (ΔH = kj mol -1 ) assigned to the isotropic liquidto-mesophase transition. 75

107 Heat flow (mw) Heating Cooling Temperature ( C) Figure 4.11 DSC scans of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) Viewed under POM, 1 was observed to melt at 44 o C and to clear to an isotropic liquid phase at 112 o C. On cooling from the isotopic liquid phase, an optical texture was observed at 84.4 o C (Figure 4.12a), which then developed into elongated textures on further cooling at 73.8 o C (Figure 4.12b). Hence, complex 1 was mesogenic. (a) (b) Figure 4.12 Photomicrographs (on cooling) of [Cu(cyclam)(L) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (1) at: (a) 84.4 C and (b) 73.8 C 76

108 4.2.2 [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O a) Synthesis and structural elucidation Similar to complex 1, [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) was prepared in a stepwise reaction as shown in Scheme 4.1, using [Cu 2 (4-ClC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ].2H 2 O, cyclam, and L. [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O was obtained as a purple powder and its yield was 64.8%. Its chemical formula, based on the elemental analyses, is C 24 H 40 Cl 2 N 4 O 8 (FW= g mol -1 ; Calc.: C, 44.5; H, 6.2; N, 8.7%. Found: C, 44.0; H, 6.3; N, 8.9%). Its FTIR spectrum (Figure 4.13) showed the presence of all the expected functional groups (Table 4.3) as discussed previously. The value of Δ (176 cm -1 ) was in agreement with non-coordinated 4-ClC 6 H 4 COO - ions [ ]. 95 T% cm -1 Figure 4.13 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O 77

109 abs Table 4.3 FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (2) (R = 4-ClC 6 H 4 COO) Complex Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-O C-N [Cu(cyclam)(H 2 O) 2 ] 3392br 3180br m (asym) m (R) 2.2H 2 O 1371s (sym) br 3183br 2918s (asym) 2850s (sym) 1638m (asym) 1470s (sym) 1189s 1095m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.14) in CHCl 3 showed a broad d-d band at 541 nm (ε max = 92.4 M -1 cm -1 ), suggesting a trans-iii octahedral geometry [282, 283], similar to [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) nm Figure 4.14 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.9 x 10-6 cm 3 g -1, χ M = 1.2 x 10-3 cm 3 mol -1, and χ dia = -3.5 x 10-4 cm 3 mol -1, was 1.9 B.M. at 298 K. The value was in the range found for mononuclear Cu(II) complexes in a distorted octahedral geometry ( B.M.) [ ] similar to [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2. 78

110 Combining these data with the spectroscopic data discussed above, it is proposed that its structure was similar to [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Figure 4.3a). [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) was obtained as a purple powder and the yield was 66.7%. Its chemical formula based on the elemental analyses is C 66 H 110 Cl 2 CuN 6 O 8 (FW= g mol -1 ; Calc.: C, 63.4; H, 8.9; N, 6.7%. Found: C, 63.1; H, 8.5; N, 6.7%). Its FTIR spectrum (Figure 4.15) showed the presence of all the expected functional groups as discussed previously. The value of Δ (168 cm -1 ) suggested non coordinated 4-ClC 6 H 4 COO - ions [ ] T% cm Figure 4.15 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) Its UV-vis spectrum (Figure 4.16) in CHCl 3 showed a broad d-d band at 541 nm (ε max = 45.0 M -1 cm -1 ), suggesting a trans-iii octahedral geometry [282, 283], similar to 1. 79

111 abs nm Figure 4.16 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) Its µ eff value calculated from the values of FM = g mol -1, χ g = 0.3 x 10-6 cm 3 g -1, χ M = 4.1 x 10-4 cm 3 mol -1, and χ dia = -8.1 x 10-4 cm 3 mol -1, was 1.7 B.M. at 298 K, suggested a mononuclear complex with octahedral geometry around Cu(II) (1.73 B.M.) [109], similar to 1. Combining these data with the spectroscopic data discussed above, it is proposed that the structural formula for 2 ([Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O) was similar to 1 (Figure 4.8). b) Thermal behavior The TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (Figure 4.17) showed an initial weight loss of 5.0% (expected, 5.6%) from 69 o C to about 103 o C due to the evaporation of lattice H 2 O, followed by 81.4% (expected, 84.6%) from 240 o C to about 660 o C due to the evaporation of coordinated H 2 O, decomposition of cyclam ligand and 4-ClC 6 H 4 COO ions, leaving 13.6% residue at temperatures above 642 o C (expected, 9.8% assuming CuO) [66, 291, 292]. The result is in agreement with its chemical formula, and the complex was thermally as stable as [Cu(cyclam)(H 2 O) 2 ] (4-FC 6 H 4 COO) 2.2H 2 O (T dec = 240 o C). 80

112 Weight (%) Weight% Temperature ( C) Figure 4.17 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O The TGA trace (Figure 4.18) of 2 showed an initial weight loss of 5.0% (expected, 5.5%) from 74 o C to about 150 o C due to the evaporation of the lattice H 2 O, followed by 89.1% (expected, 84.7%) from 226 o C to about 675 o C due to the evaporation of the coordinated H 2 O, cyclam and 4-hexadecyloxypyridine ligands and 4-ClC 6 H 4 COO - ions, leaving 5.9% residue above 675 o C (expected, 9.8% assuming CuO) [66, 291, 292]. Thus its decomposition temperature was 226 o C. The result is in agreement with its chemical formula, and it was thermally as stable as 1 (T dec = 226 o C) Temperature ( C) Figure 4.18 TGA trace for [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) 81

113 Heat flow (mw) c) Mesomorphic properties The DSC of 2 was recorded in the temperature range o C. The scans (Figure 4.19) showed three broad endothermic peaks at 42.3 C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, at 81.3 C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition, and at C (ΔH = kj mol -1 ) assigned to mesophase-to isotropic liquid phase transition on heating. On cooling, a broad exothermic peak at 77.0 C (ΔH = kj mol -1 ) assigned to the isotropic liquid-tomesophase transition. 8 6 Heating Cooling Temperature ( C) Figure 4.19 DSC scans of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) Viewed under POM, the sample was observed to melt at 42 o C and to clear to an isotropic liquid phase at 113 o C. On cooling from the isotopic liquid phase, an optical texture was first observed at 100 o C (Figure 4.20a), which then coalesced at 84 o C (Figure 4.20b) on further cooling. Hence, 2 was mesogenic. 82

114 (a) (b) Figure 4.20 Photomicrographs (on cooling) of [Cu(cyclam)(L) 2 ](4-ClC 6 H 4 COO) 2.2H 2 O (2) at: (a) 100 C and (b) 84 C [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O a) Synthesis and structural elucidation Similar to complexes 1 and 2, [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) was prepared in a stepwise reaction as shown in Scheme 4.1, using [Cu 2 (4-BrC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ].2H 2 O, cyclam, L and ethanol. [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O was obtained as a purple powder and the yield was 57.7%. Its chemical formula based on the elemental analyses is C 24 H 40 Br 2 N 4 O 8 (FW = g mol -1 ; Calc.: C, 39.2; H, 5.5; N, 7.6%. Found: C, 39.5; H, 5.7; N, 7.9%). Its FTIR spectrum (Figure 4.21) showed the presence of all of the expected functional groups (Table 4.4). The value of Δ (170 cm -1 ) suggested non-coordinated 4-BrC 6 H 4 COO - ions [ ]. 83

115 T% cm -1 Figure 4.21 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O Table 4.4 FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (3) (R = 4-BrC 6 H 4 COO) Complex Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-O C-N [Cu(cyclam)(H 2 O) 2 ] 3373br 3191br m (asym) m (R) 2.2H 2 O 1379s (sym) br 3182br 2917s (asym) 2851s (sym) 1638m (asym) 1472s (sym) 1189s 1097m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.22) in chloroform showed a broad d-d band at 544 nm (ε max = 78.6 M -1 cm -1 ), suggesting a trans-iii [282, 283] octahedral geometry similar to [Cu(cyclam)(H 2 O) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (X = F, Cl). 84

116 abs nm Figure 4.22 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.5 x 10-6 cm 3 g -1, χ M = 1.1 x 10-3 cm 3 mol -1, and χ dia = -3.7 x 10-4 cm 3 mol -1, was 1.9 B.M. at 298 K. This is in agreement with a mononuclear Cu(II) in a distorted octahedral geometry [ ], as similarly suggested for [Cu(cyclam)(H 2 O) 2 ] (4-XC 6 H 4 COO) 2.2H 2 O (X = F, Cl). Combining the instrumental data discussed above, it is proposed that the structural formula for [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O was similar to [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Figure 4.3a). [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) was obtained as a purple powder and the yield was 61.0%. Its chemical formula, based on the results of elemental analyses, is C 66 H 110 Br 2 CuN 6 O 8 (FW= g mol -1 ; Calc.: C, 59.2; H, 8.3; N, 6.3%. Found: C, 59.9; H, 8.6; N, 6.5%). Its FTIR spectrum (Figure 4.23) showed the presence of all of the expected functional groups (Table 4.4). The value of Δ (166 cm -1 ) suggested non-coordinated 4-BrC 6 H 4 COO - ions [ ]. 85

117 abs 90 T% cm -1 Figure 4.23 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) Its UV-vis spectrum (Figure 4.24) in chloroform showed a broad d-d band at 542 nm (ε max = 43.7 M -1 cm -1 ), suggesting a trans-iii [282, 283] octahedral geometry, as similarly suggested for complexes 1 and nm Figure 4.24 UV-visible spectrum of [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 2.6 x 10-7 cm 3 g -1, χ M = 3.5 x 10-4 cm 3 mol -1, and χ dia = -8.3 x 10-4 cm 3 mol -1, was 86

118 Weight% 1.7 B.M. at 298 K. This is in agreement with a mononuclear complex with octahedral geometry around Cu (II) (1.73 B.M.) [109], similar to 1 and 2. Combining the instrumental data discussed above, it is proposed that structural formula for 3 was similar to 1 (Figure 4.8) and 2. b) Thermal behavior The TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (Figure 4.25) showed an initial weight loss of 6.0% (expected, 5.0%) from 74 o C to about 92 o C due to the evaporation of lattice H 2 O, followed by 86.1% (expected, 86.4%) from 242 o C to about 760 o C due to the evaporation of coordinated H 2 O, decomposition of the cyclam ligand and 4-BrC 6 H 4 COO - ions, leaving 7.9% residue at temperatures above 760 o C (expected, 8.6%, assuming CuO) [66, 291, 292]. Thus these results supported its chemical formula, and its decomposition temperature was 242 o C. Hence it was as stable as [Cu(cyclam)(H 2 O) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (T dec = 240 and 242 o C for X = F and Cl respectively) Temperature( C) Figure 4.25 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O 87

119 Weight (%) The TGA trace for 3 (Figure 4.26) showed an initial weight loss of 4.0% (expected, 2.7%) from 51 o C to about 138 o C due to evaporation of lattice H 2 O, followed by 91.7% (expected, 92.6%) from 224 o C to about 836 o C due to the decomposition of cyclam and 4-hexadecyloxypyridine ligands and 4-BrC 6 H 4 COO ion, leaving 4.3% residue at temperatures above 836 o C (expected, 4.7% assuming CuO) [66, 291, 292]. Thus, these results supported its chemical formula, and its decomposition temperature was 224 o C. Hence it was as stable as 1 and 2 (T dec = 224 o C and 226 o C respectively) Temperature ( C) Figure 4.26 TGA trace for [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) c) Mesomorphic properties The DSC for 3 was recorded in the temperature range C. The scans (Figure 4.27) showed, on heating, three endothermic peaks at 42.3 C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, 81.3 C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition, and C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition on 88

120 Heat flow (mw) heating. On cooling, there was an exothermic peak at 72.7 C (ΔH = -2.2 kj mol -1 ) assigned to the isotropic liquid-to-mesophase transition. 8 6 Heating Cooling Temperature ( C) Figure 4.27 DSC scans of [Cu(cyclam)(L) 2 ](4-BrC 6 H 4 COO) 2.2H 2 O (3) Viewed under POM, the sample was observed to melt at 42 o C and to clear to an isotropic liquid phase at 111 o C. On cooling from the isotropic liquid phase, an optical texture was observed at 78.0 o C. The texture captured 77.3 o C is shown in Figure Hence, 3 was mesogenic. Figure 4.28 Photomicrograph (on cooling) of [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (3) (R = 4-BrC 6 H 4 COO) at 77.3 C 89

121 4.2.4 [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O a) Synthesis and structural elucidation Similar to complexes 1-3, [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) was prepared in a stepwise reaction as shown in Scheme 4.1, using [Cu 2 (4-IC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ].2H 2 O, cyclam and L. [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2.2H 2 O was obtained as a purple powder and the yield was 69.2%. Its chemical formula, based on the elemental analyses, is C 24 H 40 I 2 N 4 O 8 (FW = g mol -1 ; Calc.: C, 34.7; H, 4.9; N, 7.7%, Found: C, 35.2; H, 4.8; N, 7.5%). Its FTIR spectrum (Figure 4.29) showed the presence of all of the expected functional groups (Table 4.5). The value of Δ (166 cm -1 ) suggested non-coordinated 4-IC 6 H 4 COO - ions [ ] T% cm -1 Figure 4.29 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2 2H 2 O 90

122 abs Table 4.5 FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (4) (R = 4-IC 6 H 4 COO) Complex Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-O C-N [Cu(cyclam)(H 2 O) 2 ] 3375br 3189br m (asym) m (R) 2 2H 2 O 1378s (sym) br 3213br 2917s (asym) 2851s (sym) 1638m (asym) 1472s (sym) 1192s 1097m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.30) in chloroform showed a broad d-d band at 544 nm (ε max = 75.7 M -1 cm -1 ), suggesting a trans-iii [282, 283] octahedral geometry similar to [Cu(cyclam)(H 2 O) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (X = F, Cl, Br) nm Figure 4.30 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2 2H 2 O Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.5 x 10-6 cm 3 g -1, χ M = 1.2 x 10-3 cm 3 mol -1, and χ dia = -3.9 x 10-4 cm 3 mol -1, was 2.0 B.M. at 298 K. This is in agreement with a mononuclear Cu(II) in a distorted octahedral geometry [ ], as similarly suggested for [Cu(cyclam)(H 2 O) 2 ] (4-XC 6 H 4 COO) 2.2H 2 O (X = F, Cl, Br). 91

123 Combining the instrumental data discussed above, it is proposed that the structural formula for [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2.2H 2 O was similar to [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2.2H 2 O (Figure 4.3a). [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) was obtained as a purple powder and the yield was 64.0%. Its chemical formula based on the elemental analyses is C 66 H 110 CuI 2 N 6 O 8 (FW= g mol -1 ; Calc.: C, 55.3; H, 7.7; N, 5.9%. Found: C, 55.5; H, 7.5; N, 5.1%). Its FTIR spectrum (Figure 4.31) showed the presence of all of the expected functional groups (Table 4.5). The value of Δ (166 cm -1 ) suggested non-coordinated 4-IC 6 H 4 COO - ions [ ] T% cm -1 Figure 4.31 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) Its UV-vis spectrum (Figure 4.32) in chloroform showed a broad d-d band at 542 nm (ε max, M -1 cm -1 ), suggesting a trans-iii [282, 283] octahedral geometry, as similarly suggested for complexes 1, 2 and 3. 92

124 abs nm Figure 4.32 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 2.4 x 10-7 cm 3 g -1, χ M = 3.4 x 10-4 cm 3 mol -1, and χ dia = -8.6 x 10-4 cm 3 mol -1, was 1.7 B.M. at 298 K. This is in agreement with a mononuclear complex with octahedral geometry around Cu(II) (1.73 B.M.) [109], similar to 1, 2, and 3. Combining the instrumental data discussed above it is proposed that structural formula for 4 is similar to 1 (Figure 4.8), 2, and 3. b) Thermal behavior The TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (Figure 4.33) showed an initial weight loss of 4.7% (expected, 4.3%) from 63 o C to about 95 o C due to the evaporation of lattice H 2 O, followed by 83.3% (expected, 88.0%) from 241 o C to about 713 o C due to the evaporation of coordinated H 2 O, decomposition of cyclam ligand and 4-IC 6 H 4 COO - ion, leaving 12.0% residue at temperatures above 713 o C (expected, 7.7%, assuming CuO) [66, 291, 292]. These results supported its chemical formula, and its decomposition temperature was 241 o C, Hence it was as stable as [Cu(cyclam)(H 2 O) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (T dec = 240, 242, and 242 o C for X = F, Cl, and Br respectively). 93

125 Weight (%) Temperature ( C) Figure 4.33 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-IC 6 H 4 COO) 2.2H 2 O The TGA trace for 4 (Figure 4.34) showed an initial weight loss of 3.2% (expected, 2.51%) from 46 o C to about 113 o C due to the evaporation of lattice H 2 O, followed by 91.0% (expected, 93.1%) from 223 o C to about 708 o C due to the evaporation of coordinated H 2 O, decomposition of cyclam and 4-hexadecyloxypyridine ligands, and 4-IC 6 H 4 COO - ion, leaving 5.8% residue at temperatures above 708 o C (expected, 4.43%, assuming CuO) [66, 291, 292]. These results supported its chemical formula and its decomposition temperature was 223 o C. Hence it was as stable as 1, 2, and 3 (T dec = 224, 226, and 224 o C, respectively). 94

126 Weight (%) Temperature ( C) Figure 4.34 TGA trace for [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) c) Mesomorphic properties The DSC of 4 was recorded in the temperature range C. The scans (Figure 4.35) shoed on heating three endothermic peaks at 42.0 C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, 52.7 C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition, and 95.3 C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition. On cooling an exothermic peak at 69.7 C (ΔH = -2.8 kj mol -1 ) assigned to the isotropic liquid-to-mesophase transition and an exothermic peak at 26.0 C (ΔH = kj mol -1 ) assigned to the mesophase-to-crystal transition. 95

127 Heat flow (mw) Heating Cooling Temperature ( C) Figure 4.35 DSC scans of [Cu(cyclam)(L) 2 ](4-IC 6 H 4 COO) 2.2H 2 O (4) Viewed under POM, the powder was observed to melt at 45.0 o C and to clear to an isotopic liquid at 97.0 o C. On cooling from the isotopic liquid phase, an optical texture was observed at 71.9 o C (Figure 4.36). Hence, 4 was mesogenic. Figure 4.36 Photomicrograph (on cooling) of [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (4) (R = 4-IC 6 H 4 COO) at 71.9 C 96

128 4.2.5 [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2 a) Synthesis and structural elucidation Similar to complexes 1 4, [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) was prepared in a stepwise reaction as shown in Scheme 4.1, using [Cu 2 (4-NO 2 C 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ].2H 2 O, cyclam, and L. [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O was obtained as purple-needleshaped crystals and the yield was 68.4%. Its chemical formula, based on the results of elemental analyses, is C 26 H 46 CuN 6 O 12 (FW= g mol -1 ; Calc.: C, 44.7; H, 6.6; N, 12.0%. Found: C, 44.9; H, 6.3; N, 12.4%). [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O crystallized in the monoclinic system with the space group P 2 1 /c. Crystal data and refinement details are given in Table 1 (APPENDIX A) and selected bond lengths and angles are given in Table 4 (APPENDIX A). Its single crystal X-ray crystallography showed centrosymmetric and octahedral trans-n 4 O 2 donor set [Cu N1 = (18) Å, Cu N2 = (18) Å and Cu O1W = 2.529(2) Å] (Figure 4.37a), similar to [Cu(cyclam)(H 2 O) 2 ] (4-FC 6 H 4 COO) 2.2H 2 O. The 4-nitrocarboxylate ions were associated with the complex cation by aqua-o-h...o3 hydrogen bonds and an intramolecular N2 H O4 hydrogen bonds. The relatively long Cu1-O1W distance compared to Cu-N1 and Cu-N2 was a consequence of the Jahn-Teller distortion that caused the cationic complex to exhibit axial elongation. Significant hydrogen bonding was also apparent in its crystal structure (Table 4.6). Thus, the second carboxylate-o4 atom hydrogen bonds to the aqua-h1w atom of second complex cation, so that the carboxylate oxygen atom O4 was bifurcated. The result was that each complex cation was surrounded by four carboxlyate anions with each of these associations stabilised by an eight-membered {...HNCuOH...OCO} synthon. A supramolecular chain along the b-axis occured as complex cations were 97

129 bridged by centrosymmetric 12-membered {...OHO...OCO} 2 synthons involving the carboxylate anions and aqua ligand as illustrated in Figure 4.37b. (a) (b) Figure 4.37 (a) Molecular view, showing displacement ellipsoids at 50% probability level and (b) supramolecular chain for [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O; most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity. The O H O and N H O hydrogen bond shown as blue and green dashed lines respectively, lead to a chain. Colour code: Cu, light blue; O, red; N, blue; and C, grey Table 4.6 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O [Å and ] D-H...A d(d-h) d(h...a) d(d A) <(DHA) O1W-H1W O (2) 1.874(2) 2.806(3) 158.3(1) O1W-H2W O (2) 1.930(2) 2.749(3) 164.9(1) N2-H2 O (2) 2.057(2) 2.929(3) 160.0(1) 98

130 Its FTIR spectrum (Figure 4.38) showed the presence of all of the expected functional groups (Table 4.7). The value of Δ (175 cm -1 ) suggested non-coordinated 4-NO 2 C 6 H 4 COO - ion [ ], as revealed from its crystal structure. 100 T% cm -1 Figure 4.38 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O Table 4.7 FTIR data and assignments of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O and [Cu(cyclam)(L) 2 ](R) 2.2H 2 O (5) (R = 4-NO 2 C 6 H 4 COO) Complex Wavenumber, (cm -1 ) [Cu(cyclam)(H 2 O) 2 ] (R) 2.2H 2 O O-H N-H CH 2 N-O COO C-O C-N 3348br 3163br m m (asym) (asym) s (sym) (sym) br 3188br 2916s (asym) 2851s (sym) br, broad; s, strong; m, medium; w, weak m (asym) 1473s (sym) 1189s 1083m Its UV-vis spectrum (Figure 4.39) in CHCl 3 showed a broad d-d band at 540 nm (ε max = 24.5 M -1 cm -1 ), suggesting a trans-iii [282, 283] octahedral geometry similar to [Cu(cyclam)(H 2 O) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (X = F, Cl, Br, I). 99

131 abs nm Figure 4.39 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.9 x 10-6 cm 3 g -1, χ M = 1.3 x 10-3 cm 3 mol -1, and χ dia = -3.3 x 10-4 cm 3 mol -1, was 2.0 B.M. at 298 K. This is in agreement with a mononuclear Cu(II) in a distorted octahedral geometry [ ], as similarly suggested for [Cu(cyclam)(H 2 O) 2 ] (4-XC 6 H 4 COO) 2.2H 2 O (X = F, Cl, Br, I). [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) was obtained as a purple powder (Scheme 4.1). The yield was 60.8%. Its chemical formula, based on the results of the elemental analyses, is C 66 H 110 CuN 8 O 12 (FW= g mol -1 ; Calc.: C, 62.3; H, 8.7; N, 8.8%. Found: C, 62.7; H, 8.5; N, 9.0%). Its FTIR spectrum (Figure 4.40) shows the presence of all of the expected functional groups (Table 4.7). The value of Δ (165 cm -1 ) suggested non-coordinated 4-NO 2 C 6 H 4 COO - ions [ ]. 100

132 abs T% cm -1 Figure 4.40 FTIR spectrum of [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) Its UV-vis spectrum (Figure 4.41) in CHCl 3 showed a broad d-d band at 541 nm (ε max = 36.6 M -1 cm -1 ), suggesting a trans-iii [282, 283] octahedral geometry, as similarly suggested for complexes nm Figure 4.41 UV-vis spectrum of [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 3.3 x 10-7 cm 3 g -1, χ M = 4.2 x 10-4 cm 3 mol -1, and χ dia = -7.9 x 10-4 cm 3 mol -1, was 101

133 Weight% 1.7 B.M. at 298 K. This is in agreement with a mononuclear complex with octahedral geometry around Cu(II) (1.73 B.M.) [109]. Combining the instrumental data discussed above, it is proposed that structural formula for 5 is similar to 1 (Figure 4.8) and 2-4. b) Thermal behavior The TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (Figure 4.42) showed an initial weight loss of 2.0% (expected, 5.1%) from 60 o C to about 75 o C due to the evaporation of lattice H 2 O, followed by 83.0% (expected, 85.8%) from 262 o C to about 622 o C due to the evaporation of coordinated H 2 O, and decomposition of cyclam ligand and 4-NO 2 C 6 H 4 COO - ions, leaving 15.0% residue at temperatures above 622 o C (expected, 9.1% assuming CuO) [66, 291, 292]. Hence, the result was in agreement with its chemical formula, and its decomposition temperature was 262 o C. Thus, the complex was more stable than [Cu(cyclam)(H 2 O) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (T dec = 240 o C (X = F), 242 o C (X = Cl), 242 o C (X = Br), and 241 o C (X = I) Temperature( C) Figure 4.42 TGA trace for [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O 102

134 Weight (%) The TGA trace for 5 (Figure 4.43) showed an an initial weight loss of 3.2% (expected, 2.8%) from 44 o C to about 123 o C due to the evaporation of lattice H 2 O, followed by 92.8% from 200 o C to about 634 o C due to the decomposition of cyclam and 4-hexadecyloxypyridine ligands and 4-NO 2 C 6 H 4 COO ions (expected, 92.2%), leaving 4.0% residue at temperatures above 634 o C (expected, 5.0% assuming CuO) [66, 291, 292]. Hence, the result was in agreement with its chemical formula, and its decomposition temperature was 200 o C. Thus, the complex was less stable than its precursor [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (T dec, 262 o C), and also less stable than the corresponding complexes 1-4 (T dec = 224 o C, 226 o C, 224 o C and 223 o C respectively) Temperature ( C) Figure 4.43 TGA trace for [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) c) Mesomorphic properties The DSC of 5 was recorded in the temperature range C. The scans (Figure 4.44) showed a strong endothermic peak at 40.8 C (ΔH = kj mol -1 ) on heating assigned to its melting, and a weak exothermic peak at 54.6 C (ΔH = -1.5 kj mol -1 ) on cooling assigned to the reformation of some weak bonds. 103

135 Heat flow (mw) 10 8 Heating Cooling Temperature ( C) Figure 4.44 DSC scans of [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (5) Viewed under POM it was observed to melt at 46 C. However, no optical texture was observed on cooling from 180 o C. Hence, unlike the corresponding complexes discussed above, 5 was non mesogenic. This may arose from its lower stability, as revealed from TGA. The strongly electron-attracting NO 2 group in 4-NO 2 C 6 H 4 COO - ion weakened the bond between the phenyl carbon and the carboxyl carbon. Accordingly on heating, the complex melted and then decomposed as 4-NO 2 C 6 H 4 COO - ion loss CO 2 gas [293] [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] a) Synthesis and structural elucidation [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] was prepared in a reaction as shown in Scheme 4.1 (first step) using[cu 2 (3,5-(NO 2 ) 2 C 6 H 3 COO) 4 (H 2 O) 2 ], cyclam and etahanol. It was obtained as black block crystals and the yield was 63.0%. Its chemical formula based on the elemental analyses is C 28 H 42 CuN 8 O 12 (FW = g mol -1 ; Calc.: C, 45.1; H, 5.7; N, 15.0%. Found: C, 45.6; H, 5.5; N, 14.8%). The complex (Figure 4.45a) crystallized in the monoclinic system with the space group P 2 1 /c. Crystal data and refinement details are given in Table 1 104

136 (APPENDIX A) and selected bond lengths and angles are given in Table 4 (APPENDIX A). Its single crystal X-ray crystallography showed no coordinated H 2 O at Cu(II), which contrast with [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O. The Cu atom was located on a crystallographic centre of inversion and existed within a trans-n 4 O 2 donor set, being tetra-coordinated by the four aza-n atoms of cyclam [Cu N1 = 1.993(6) Å, Cu N2 = 1.992(6) Å and Cu O1 = 2.465(4)Å]. These Cu-N equatorial and Cu-O axial bonds were shorter than those in [Cu(cyclam)(H 2 O) 2 ] (4- NO 2 C 6 H 4 COO) 2.2H 2 O. Another exception was that two trans-o atoms were derived from 3,5-dinitrocarboxylate ions, which were monocoordinated to the Cu(II) atom. The resulting coordination geometry was based on an octahedron. Only two types of hydrogen bonding were apparent in its crystal structure (Table 4.8). The second O2 atom of carboxylate ligand was hydrogen bonded to the amine N2-H of the complex cation to form intramolecular hydrogen bond. The intermolecular forces were governed by the N-O H-N1 hydrogen bonds contributed by the terminal nitro groups mediated the linkage of the macromolecules to form a two dimensional array (Figure 4.45b). Table 4.8 Selected Hydrogen bonds for [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] [Å and ] D-H...A d(d-h) d(h...a) d(d A) <(DHA) N2-H2 O (6) 2.207(5) 3.010(7) 146.8(4) N1-H1 O (6) 2.316(6) 3.042(9) 136.6(4) 105

137 (a) (b) Figure 4.45 (a)molecular view, showing displacement ellipsoids at 50% probability level and (b) Supramolecular association operating in the crystal structure of [Cu(cyclam) (3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ]. The intermolecular N H O hydrogen bonding (green dashed lines) leads to a two-dimensional array.intramolecular N H...O-N hydrogen bonds are shown as blue dashed lines.colour code: Same as in Figure 4.37 Its FTIR spectrum (Figure 4.46) showed one broad band at 3113 cm -1 for N-H stretching of secondary amine, a medium band at 1581 cm -1 and a strong band at 106

138 abs 1347 cm -1 for asym COO and sym COO stretching, respectively, and a medium band at 1070 cm -1 for C-N stretching. The value of Δ (234 cm -1 ) was in agreement with monodentate 3,5-(NO 2 ) 2 C 6 H 3 COO ligand [294], as revealed from its crystal structure T% cm Figure 4.46 FTIR spectrum of [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] Its UV-vis spectrum (Figure 4.47) in CHCl 3 showed a broad d-d band at 540 nm (ε max, 61.6 M -1 cm -1 ), suggesting a trans-iii [282, 283] octahedral geometry, similar to [Cu(cyclam)(H 2 O) 2 ](4-XC 6 H 4 COO) 2.2H 2 O (X = F, Cl, Br, I and NO 2 ). This suggests that its octahedral geometry was maintained in this solution nm Figure 4.47 UV-vis spectrum of [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] 107

139 Weight (%) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.7 x 10-6 cm 3 g -1, χ M = 1.2 x 10-3 cm 3 mol -1, and χ dia = -2.9 x 10-4 cm 3 mol -1, was 1.9 B.M. at 298 K. This is in agreement with a mononuclear Cu(II) in a distorted octahedral geometry [ ], as similarly suggested for [Cu(cyclam)(H 2 O) 2 ] (4-XC 6 H 4 COO) 2.2H 2 O (X = F, Cl, Br, I and NO 2 ). b) Thermal behavior Its TGA trace (Figure 4.48) showed an initial weight loss of 87.5% (expected, 91.4%) from 266 o C to about 570 o C due to the decomposition cyclam and 3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ligands, leaving 12.5% residue at temperaturesabove 570 o C (expected, 9.3% assuming CuO) [66, 291, 292]. The result was in agreement with its chemical formula, and its decomposition temperature was 266 o C. Thus, the complex was as stable [Cu(cyclam)(H 2 O) 2 ](4-NO 2 C 6 H 4 COO) 2.2H 2 O (T dec = 262 o C) Temperature ( C) Figure 4.48 TGA trace for [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ] Finally, this complex did not react with L, which suggests strong 3,5-(NO 2 ) 2 C 6 H 3 COO-Cu bonds. 108

140 4.3 Concluding remarks Copper(II) arylcarboxylates, [Cu 2 (4-XC 6 H 4 COO) 4 ] (X = F, Cl, Br, I, NO 2 ) reacted with cyclam to form ionic mononuclear complexes [Cu(cyclam)(H 2 O) 2 ] (4-XC 6 H 4 COO) 2.2H 2 O, while [Cu 2 (3,5-(NO 2 )C 6 H 3 COO) 4 ] reacted with cyclam to form covalent mononuclear complex [Cu(cyclam)(3,5-(NO 2 ) 2 C 6 H 3 COO) 2 ], in good yields (57-69%). These complexes have similar magnetic susceptibilities (μ eff = B.M.) and thermal stabilities (T dec = C). Thus, it can be deduced that their magnetic and thermal properties were not significantly influenced by the electronic effect of the substituent(s) on the aromatic ring, or the coordination modes of the arylcarboxylates. These complexes, except [Cu(3,5-(NO 2 )C 6 H 3 COO) 2 (cyclam)], reacted with L (hexadecyloxypyridine) to form ionic mononuclear complexes [Cu(cyclam)(L) 2 ] (4-XC 6 H 4 COO) 2.2H 2 O in good yields (60-68%). These complexes also have similar magnetic susceptibilities (μ eff = 1.7 B.M.) and thermal stabilities (T dec = C). Except for [Cu(cyclam)(L) 2 ](4-NO 2 C 6 H 4 COO) 2, these complexes were mesomorphic. 4.4 [Cu(cyclam)(H 2 O) 2 ](4-ROC 6 H 4 COO) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 2H 2 O a) Synthesis and structural elucidation [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (6) was prepared in a stepwise reaction as shown in Scheme

141 4-HOC 6 H 4 COOC 2 H 5 + CH 3 (CH 2 ) 9 Br K 2 CO 3, KI DMF, reflux, 24 h 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H 5 KOH, CH 3 CH 2 OH reflux, 3 h 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK CuSO 4.5H 2 O, 30 min [Cu 2 [(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Cyclam, CH 3 CH 2 OH, 30 min [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O Scheme 4.2 Synthesis of [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (6) 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H 5 was obtained as a white powder (Scheme 4.2). The yield was 88.6%. Its chemical formula, based on the elemental analyses, is C 19 H 30 O 3 (FW = g mol -1 ; Calc.: C, 74.5; H, 9.8%. Found: C, 74.6; H, 9.5%). Its 1 H-NMR spectrum (Figure 4.49) showed two doublets at 7.9 ppm and 6.8 ppm for the aromatic protons (H1, H2), a quartet at 4.2 ppm for two methylene (CH 3 CH 2 O-) protons (H3), a triplet at 3.9 ppm for two methylene (CH 3 (CH 2 ) 8 CH 2 O-) protons (H4), a multiplet at 1.3 ppm for three methyl (CH 3 CH 2 O-) protons (H5), a multiplet in the range ( ) ppm for sixteen methylene (CH 3 (CH 2 ) 8 CH 2 O-) protons (H6), and a triplet at 0.80 ppm for three methyl (CH 3 (CH 2 ) 8 CH 2 O-) protons (H7). 110

142 H6 H7 H1 H2 H3 H4 H5 Figure H-NMR spectrum of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H 5 Its FTIR data are collected in Table 4.10 (which also contains the data for corresponding metal complexes for later discussion). Its FTIR spectrum (Figure 4.50) showed two strong bands at 2916 cm -1 and 2847 cm -1 for ʋ asym CH 2 and ʋ sym CH 2 respectively, a strong band at 1711 cm -1 for C=O stretching frequency of ester group, a strong band at 1510 cm -1 and a medium band at 1311 cm -1 for ν asym COO and ν sym COO stretching frequency, respectively, and a strong band at 1243 cm -1 for C-O stretching frequency of the ether group (Table 4.9) T% cm -1 Figure 4.50 FTIR spectrum of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H 5 111

143 Thus the elemental analyses, 1 H-NMR and FTIR results confirmed its structure as shown in Figure Table 4.9 FTIR data and assignments of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOC 2 H 5 and its corresponding metal complexes Compound Wavenumber, (cm -1 ) O-H N-H CH 2 C=O COO C-O C-N RCOOC 2 H s (asym) 2847s (sym) RCOOK s (asym) 2852s [Cu 2 (RCOO) 4 (H 2 O) 2 ].2H 2 O (sym) 3358br s (asym) 2852s (sym) br 3130m 2925s (asym) 2861s (sym) 1711s 1510s (asym) 1311m (sym) m (asym) 1390m (sym) m (asym) 1337m (sym) m (asym) 1377m (sym) R = 4-CH 3 (CH 2 ) 9 OC 6 H 4, br, broad; s, strong; m, medium; w, weak. 1243s s s 1103m 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK was obtained as a white powder (Scheme 4.2) and the yield was 79.1%. Its chemical formula, based on the elemental analyses, is C 17 H 25 KO 3 (FW = g mol -1 ; Calc.: C, 64.5; H, 7.9%. Found: C, 65.0; H, 8.1%). Its FTIR spectrum (Figure 4.51) showed two strong bands at 2921 cm -1 and 2852 cm -1 for ν asym CH 2 and ν sym CH 2 respectively, a strong band at 1558 cm -1 and a medium band at 1390 cm -1 for ν asym COO and ν sym COO stretching frequency, respectively, and a strong band at 1247 cm -1 for C-O stretching frequency of the ether group (Table 4.10). The value (168 cm -1 ) is in agreement with 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ions [ ]. 112

144 T% cm -1 Figure 4.51 FTIR spectrum of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK Accordingly, the elemental analyses and FTIR spectrum confirmed its structure shown in Figure O K + -O O H 2 C C H 2 H 2 C C H 2 H 2 C C H 2 H 2 C C H 2 H 2 C CH 3 Figure 4.52 Structure of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COOK [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was obtained as a blue powder and the yield was 52.4%. Its chemical formula, based on the elemental analyses, is C 68 H 112 Cu 2 O 18 (FW = g mol -1 ; Calc.: C, 60.5; H, 8.4%. Found: C, 60.9; H, 8.5%). Its FTIR spectrum (Figure 4.53) showed a broad peak at 3358 cm -1 for O-H stretching of H 2 O, two strong peaks at 2919 cm -1 and 2852 cm -1 for ν asym CH 2 and ν sym CH 2 respectively, a medium peak at 1594 cm -1 for ν asym COO and a strong peak at 1337 cm -1 for ν sym COO (Table 4.10). The COO value (ν asym COO ν sym COO) was 157 cm -1, suggesting bridging bidentate 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands [79]. 113

145 abs T% cm -1 Figure 4.53 FTIR spectrum of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Its UV-vis spectrum (Figure 4.54) in CHCl 3 showed a broad d-d band at about 673 nm (ε max = 492 M -1 cm -1 ) and a shoulder at about 370 nm, indicating a binuclear complex with square pyramidal geometry at Cu(II) [83, ] nm Figure 4.54 UV-vis spectrum of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O The µ eff value, calculated from the values of FM = g mol -1, χ g = 1.1 x 10-6 cm 3 g -1, χ M = 1.5 x 10-3 cm 3 mol -1, and χ dia = -7.7 x 10-4 cm 3 mol -1, was 2.4 B.M. at 298 K. This is in agreement with the expected spin-only value of square-pyramidal copper(ii) dinuclear complexes ( B.M.) [289, 290, 299, 300]. 114

146 Combining these instrumental data discussed above, the proposed structural formula for the complex is [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (Figure 4.55). RO OH 2 OR O O O Cu Cu O O O O O OH 2 OR RO Figure 4.55 Schematic representation of the proposed structure of [Cu 2 (4-ROC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (R = CH 3 (CH 2 ) 9 ); lattice water are not shown [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2.2H 2 O (6) was obtained as purple block crystals (Scheme 4.2) and the yield was 56.7%. Its chemical formula, based on the elemental analyses, is C 44 H 78 CuN 4 O 8 (FW = g mol -1 ; Calc.: C, 59.3; H, 9.2; N, 6.3%. Found: C, 59.7; H, 9.8; N, 6.5%). The complex (Figure 4.56a) crystallized in the triclinic system with the space group P-1. Crystal data and refinement details are given in Table 1 (APPENDIX A) and selected bond lengths and angles are given in Table 4 (APPENDIX A). Its singlecrystal XRD showed a centrosymmetric and octahedral trans-n 4 O 2 donor set [Cu N1 = 2.024(2) Å, Cu N2 = 2.006(2) Å and Cu O1W = 2.595(2) Å] and an axial elongation due to Jahn-Teller distortion similar to complex 1. Significant hydrogen bonding was observed in the crystal structure of 6 (Table 4.10). Each 4-decyloxycarboxylate ion associated with the complex cation by aqua-oh...o1 hydrogen bond and the amine-n2-h of the second complex cation was connected to this carboxylate-o1 atom through N2-H O1 hydrogen bond. Every carboxylate oxygen atom formed the similar hydrogen bonds and thus all of those were 115

147 bifurcated. Thus each complex cation was surrounded by four carboxylate anions with each of these associations stabilised by an eight-membered {...HNCuOH...OCO} synthon. A supramolecular chain along the b-axis occured as complex cations were bridged by centrosymmetric 12-membered {...OHO...OCO} 2 synthons involving the carboxylate anions and aqua ligand as illustrated in Figure 4.56b. As the complex cations each lied on a centre of inversion, similar hydrogen bonds were formed on the other side of each CuN 4 plane and the lack of significant hydrogen bonding capacity in the aryl groups in 6 resulted in a supramolecular chain (Figure 4.56b). Table 4.10 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO [Å and ] D-H...A d(d-h) d(h...a) d(d...a) <(DHA) O1W-H1WA O (1) 2.073(1) 2.840(2) 176.7(1) O1W-H1WB O (1) 2.014(1) 2.801(2) 177.7(1) N1-H1 O (1) 2.055(1) 2.929(2) 160.5(1) N2-H2 O (1) 2.011(1) 2.886(2) 160.8(1) 116

148 (a) (b) Figure 4.56 (a) Molecular view of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6), showing displacement ellipsoids at 50% probability level; R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO; operator used to generate symmetry equivalent elements: -x, -y+2, -z+1; (b) supramolecular chain; most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity. The O H O and N H O hydrogen bond shown as blue and green dashed lines respectively, lead to a chain. Colour code: Same as in Figure

149 Its FTIR spectrum (Figure 4.57; Table 4.9) showed a broad peak at 3261 cm -1 for O-H stretching of H 2 O, a medium peak at 3130 cm -1 for N-H stretching of secondary amine in cyclam, a medium peak at 1543 cm -1 for ν asym COO and a strong peak at 1377 cm -1 for ν sym COO. The COO value (ν asym COO ν sym COO) was 166 cm -1, suggesting non-coordinated 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ions [ ] as revealed from its crystal structure T% cm -1 Figure 4.57 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.58) in CHCl 3 showed a broad d-d band at 545 nm (ε max = 61.4 M -1 cm -1 ), suggesting a trans-iii octahedral geometry [282, 283]. This suggests that its octahedral geometry was maintained in this solution. 118

150 abs nm Figure 4.58 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.0 x 10-6 cm 3 g -1, χ M = 8.9 x 10-4 cm 3 mol -1, and χ dia = -5.6 x 10-4 cm 3 mol -1, was 1.9 B.M. at 298 K. This is in agreement with a mononuclear Cu(II) in a distorted octahedral geometry ( B.M.) [ ]. b) Thermal behavior The TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (Figure 4.59) showed an initial weight loss of 3.0% from 100 o C to about 130 o C due to evaporation of two lattice H 2 O (expected, 2.8%), followed by 3.0% from 236 C to 261 C was due to the evaporation of two coordinated H 2 O molecules (expected, 2.8 %), 84.7% from 300 o C to about 583 o C due to the decomposition of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands (expected, 84.7%), leaving 9.3% residue above 583 o C (expected, 9.7% assuming CuO) [66, 291, 292]. Hence, the result was in agreement with its chemical formula, and its decomposition temperature was 300 o C. 119

151 Weight (%) Temperature ( C) Figure 4.59 TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O The TGA trace for 6 (Figure 4.60) showed an initial weight loss of 4.0% (expected, 4.0%) from 64 o C to about 113 o C due to evaporation of lattice H 2 O, followed by 84.2% (expected, 88.9%) from 262 o C to about 500 o C due to the evaporation of coordinated H 2 O, decomposition of cyclam ligand and 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ions, leaving 11.8% residue (expected, 7.1% assuming CuO) [66, 291, 292] at temperatures above 500 o C. Hence, the result supported its chemical formula and its decomposition temperature was 262 o C, which indicated that it was thermally less stable than its dimeric precursor (T dec = 300 o C). 120

152 Weight% Temperature ( C) Figure 4.60 TGA trace for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) c) Mesomorphic properties The DSC of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was recorded in the temperature range C. The scans (Figure 4.61) showed two endothermic peaks at o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition, on heating. On cooling a weak exothermic peak at o C (ΔH = -2.5 kj mol -1 ) assigned to isotropic liquid-to-mesophase transition and a strong exothermic peak at 89.2 o C (ΔH = kj mol -1 ) assigned to mesophase-to-crystal transition. 121

153 Heat flow (mw) Heating Cooling Temperature ( C) Figure 4.61 DSC scans of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Viewed under a polarizing optical microscope (POM), the sample was observed to melt at 130 C and to clear to an isotropic liquid phase at 204 o C on heating. On cooling from this temperature, an optical texture was first observed at 142 o C. The texture shown in Figure 4.62a was captured at 135 C. On further cooling, this texture became brighter at 92 o C (Figure 4.62b) when the sample crystallised. These observations were in accord with the DSC results. Hence, the complex is mesogenic. (a) (b) Figure 4.62 Photomicrographs (on cooling) of [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O at: (a) 135 C and (b) 92 C 122

154 Heat flow (mw) The DSC of 6 was recorded in the temperature range C. The scans (Figure 4.63) showed three endothermic peaks on heating at 58.5 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, o C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition. On cooling three exothermic peaks at o C (ΔH = kj mol -1 ) assigned to isotropic liquid-to-mesophase transition, o C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition and 71.7 C (ΔH = kj mol -1 ) assigned to mesophase-to-crystal transition Heating Cooling Temperature ( C) Figure 4.63 DSC scans of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Viewed under POM, the sample was observed to melt at 116 o C and to clear to an isotopic liquid phase at 140 o C. On cooling from this temperature, an optical texture started to develop at o C (Figure 4.64a) and became well developed at o C (Figure 4.64b). It coalesced on further cooling and became brighter at o C (Figure 4.64c). The sample crystallized at 75 o C. The observations were in accord with DSC results. Hence, it has mesogenic properties. 123

155 (a) (b) (c) Figure 4.64 Photomicrographs (on cooling) of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (6) at: (a) o C, (b) o C, and (c) o C (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) The difference in the mesogenic properties of 6 and its precursor, [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O arose from the difference in their geometry and nuclearity. Complex 6 was a mononuclear octahedral ionic complex with rod-like shape. Hence, it behaved as a calamitic liquid crystal, exhibiting batonnets and fan-shaped textures characteristic of smectic mesophase [ ]. The direct transition to the fluidic smectic phase is often accomplished by growth of elongated germs (smectic batonnets) [304], though the most commonly observed SmA phase is that of the fan-shaped textures [305]. There are many reports of batonnets coalescing into a fan-shaped texture on slow cooling of the melts into the smectic phase [302, 303, ]. In contrast, its precursor was a dinuclear complex with the paddle-wheel structure and behaved as a columnar liquid crystal [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2.2H 2 O a) Synthesis and structural elucidation Similar to complex 6, [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2.2H 2 O (7) was prepared in a stepwise reaction as shown in Scheme CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H 5 was obtained as a white powder (Scheme 4.2). The yield was 87.2%. Its chemical formula, based on the elemental analyses, is 124

156 C 21 H 34 O 3 (FW,= g mol -1 ; Calc.: C, 75.41; H, 10.25%. Found: C, 75.91; H, 11.0%). Its 1 H-NMR spectrum (Figure 4.65) showed two doublets at 7.9 ppm and 7.1 ppm for the aromatic protons (H1, H2), a multiplet at 4.3 ppm for two methylene protons (CH 3 CH 2 O-; H3), a multiplet at 3.7 ppm for two methylene protons (CH 3 (CH 2 ) 10 CH 2 O-; H4), a multiplet at 1.3 ppm for twenty methylene protons (CH 3 (CH 2 ) 10 CH 2 O-; H5), a triplet at 1.2 ppm for three methyl protons (CH 3 (CH 2 ) 11 O-; H6) and a triplet at 0.85 ppm for three methyl protons (CH 3 CH 2 O-; H7). H6 H7 H1 H2 H3 H4 H5 Figure H-NMR spectrum of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H 5 Its FTIR spectrum (Figure 4.66) showed all of the expected functional groups (Table 4.11). Thus the elemental analyses, 1 H-NMR, and FTIR results confirmed its structure as shown in Figure

157 T% cm -1 Figure 4.66 IR spectrum of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H 5 Table 4.11 FTIR data and assignments of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOC 2 H 5 and its corresponding metal complexes Compound Wavenumber, (cm -1 ) O-H N-H CH 2 C=O COO C-O C-N RCOOC 2 H s 1711s 1510s 1243s - (asym) 2847s (sym) (asym) 1311m (sym) RCOOK s m 1247s s (asym) 1386m (sym) [Cu 2 (RCOO) 4 (H 2 O) 2 ] 3400br s s - -.2H 2 O (asym) 2849s (sym) (asym) 1437m (sym) br 3262s 3184m m 1378s m R= 4-CH 3 (CH 2 ) 11 OC 6 H 4, br, broad; s, strong; m, medium; w, weak. 126

158 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOK was obtained as a white powder (Scheme 4.2) and the yield was 69.3%. Its chemical formula based on the elemental analyses is C 19 H 29 KO 3 (FW = 344.5g mol -1 ; Calc.: C, 66.2; H, 8.5%. Found: C, 67.0; H, 8.9%). Its FTIR spectrum (Figure 4.67) showed all of the expected functional groups (Table 4.12). The value for the 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ion is 185 cm -1 [ ] T% cm Figure 4.67 IR spectrum of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COOK [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was obtained as a blue powder and the yield was 67.1%. Its chemical formula, based on the elemental analyses, is C 76 H 120 Cu 2 O 14 (FW = g mol -1 ; Calc.C, 65.9; H, 8.7%. Found: C, 65.8; H, 9.3%). Its FTIR spectrum (Figure 4.68) showed all of the expected functional groups (Table 4.12). The value was 157 cm -1, suggesting bridging bidentate 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands [79]. 127

159 abs T% cm -1 Figure 4.68 FTIR spectrum of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Its UV-vis spectrum (Figure 4.69) in CHCl 3 showed a broad d-d band at 682 nm (ε max = M -1 cm -1 ) and a shoulder at about 370 nm, indicating a binuclear complex with square pyramidal geometry at Cu(II) [83, ] similar to [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O nm Figure 4.69 UV-vis spectrum of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Its µ eff value, calculated from the values of FM = g mol -1, χ g = 3.5 x 10-6 cm 3 g -1, χ M = 4.9 x 10-3 cm 3 mol -1, and χ dia = -8.3 x 10-4 cm 3 mol -1, was 3.7 B.M. at 298 K. The value was higher than expected spin-only value for dinuclear 128

160 copper(ii) complexes ( B.M.) [289, 290, 299, 300]. This is likely due to the loss of the weakly bonded H 2 O ligands at the axial positions on storage, leading to the formation of oligomeric chains (stacked dimers). It is possible that the Cu(II) atoms in the oligomers were pushed out of the basal plane to form square-based pyramidal structures. Such geometrical distortion led to ferromagnetic interactions between the metal centres, as suggested by Bencini et. al [309]. Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (Figure 4.55). Finally, [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2.2H 2 O (7) was obtained as purple block crystals, and the yield was 58.9%. Its chemical formula, based on the elemental analyses, is C 48 H 90 CuN 4 O 10 (FW = g mol -1 ; Calc.: C, 60.9; H, 9.58; N, 5.92%. Found: C, 60.2; H, 9.52; N, 6.0%). The complex (Figure 4.70a) crystallized in the triclinic system with the space group P -1. Crystal data and refinement details are given in Table 1 and selected bond lengths and angles are given in Table 4 in the APPENDIX A. Its single crystal X-ray analysis showed that crystallographic asymmetric unit comprised of two half [Cu(cyclam)(OH 2 ) 2 ] 2+ cations, as each was disposed about a centre of inversion, two carboxylate anions and a water molecule of crystallisation (Figure 4.70a). Each Cu(II) atom existed within a trans-n 4 O 2 donor set [Cu1 N1 = 2.018(2) Å, Cu1 N2 = 2.026(2) Å and Cu1 O3w = 2.472(3) Å; Cu2 N3 = 2.017(3) Å, Cu2 N4 = 2.013(2) Å and Cu2 O2w = 2.458(2) Å]. Each of the alkyl chains in the anions adopted an extended, all-trans conformation. The major difference between the anions was related to the relative orientations of the carboxylate group with respect to the phenyl ring to which it was attached, being 129

161 either twisted [O1 C6 C7 C8 torsion angle = 161.4(3)º] or co-planar with [O4 C30 C31 C32 =-175.6(3)º]. The components of the crystallographic asymmetric unit were connected via O H...O hydrogen bonds whereby aqua and solvent water molecules bridged the carboxylate-o atoms. Three amine-n1 H, N2 H, N4 H atoms formed N H...O hydrogen bonds to three carboxylate-o atoms and fourth N3 H atom hydrogen bonded to O1W atom of coordinated water with the result that three of the carboxylate-o atoms were bifurcated and the other trifurcated. As the complex cations each lied on a centre of inversion, similar hydrogen bonds were formed on the other side of each CuN 4 plane leading to a supramolecular chain with base vector [1-10] (Figure 4.70b). The chains aligned in the ab-plane with the carboxylate substituents lying on either side. The only notable contact between chains was of the type C H.... Table 4.12 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Å and ] D-H...A d(d-h) d(h A) d(d...a) <(DHA) O1W-H1WB O2 0.82(4) 1.98(4) 2.787(3) 170(4) O1W-H1WA O5 0.78(4) 2.14(3) 2.900(3) 165(4) O2W-H2WB O1 0.76(4) 2.01(4) 2.767(3) 169(4) O2W-H2WA O4 0.76(4) 2.00(4) 2.739(3) 165(4) O3W-H3WB O1 0.75(3) 2.02(4) 2.773(3) 173(4) O3W-H3WA O5 0.74(3) 2.05(4) 2.781(3) 167(4) N1-H1 O (2) 2.120(2) 2.952(3) 151.5(2) N2-H2 O (2) 2.117(2) 3.001(3) 163.4(2) N3-H3 O1W 0.910(2) 2.062(2) 2.954(3) 166.6(2) N4-H4 O (2) 1.982(2) 2.889(3) 175.0(2) 130

162 (a) (b) Figure 4.70 (a) Molecular view of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) showing displacement ellipsoids at 70% probability level (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO); operator used to generate symmetry equivalent elements: -x+2, -y+2, -z;. (b) supramolecular chain along [1-1 0]; all non-acidic hydrogen atoms have been removed for clarity. The O H O and N H O hydrogen bond shown as blue and green dashed lines respectively, lead to a chain. Colour code: Same as in Figure

163 abs Its FTIR spectrum (Figure 4.71) showed the presence of all of the expected functional groups (Table 4.11), and the Δ value was 174 cm -1, in agreement with non-coordinated 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ions [ ], as revealed from its crystal structure T% cm Figure 4.71 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.72) in CHCl 3 showed a broad d-d band at 549 nm (20.2 M -1 cm -1 ), suggesting a trans-iii octahedral geometry [282, 283], similar to nm Figure 4.72 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 132

164 Weight (%) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.3 x 10-6 cm 3 g -1, χ M = 1.2 x 10-3 cm 3 mol -1, and χ dia = -5.9 x 10-4 cm 3 mol -1, was 2.1 B.M. at 298 K. This is in agreement with a mononuclear Cu(II) in a distorted octahedral geometry ( B.M.) [ ], similar to 6. b) Thermal behavior The TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (Figure 4.73) showed an intial weight loss of 2.4% from 104 o C to about 125 o C due to evaporation of two lattice H 2 O (expected, 2.6%). The next weight loss of 88.4% from 307 o C to about 583 o C was due to evaporation of the coordinated H 2 O and decomposition of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands (expected, 88.2%), leaving 9.2% residue at temperatures above 583 o C (expected, 9.2% assuming CuO) [66, 291, 292]. Hence, the result is in agreement with its chemical formula, and it was thermally as stable (T dec = 307 o C) as [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (T dec = 300 o C) Temperature ( C) Figure 4.73 TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O The TGA trace for 7 (Figure 4.74) showed an initial weight loss of 4.0% (expected, 3.8%) from 54 o C to about 101 o C due to the evaporation of lattice H 2 O, 133

165 Weight (%) followed by 88.2% (expected, 89.5%) from 265 o C to about 587 o C due to the evaporation of the coordinated H 2 O and decomposition of cyclam and 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, leaving 7.8% residue at temperatures above 587 o C (expected, 6.7% assuming CuO) [66, 291, 292]. The result supported its chemical formula and its decomposition temperature was 265 o C. Thus it was thermally less stable than its precursor [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (T dec = 307 o C), and as stable as 6 (T dec = 262 o C) Temperature ( C) Figure 4.74 TGA trace for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) c) Mesomorphic properties The DSC of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was recorded in the temperature range C. The scans (Figure 4.75) showed three endothermic peaks at 89.2 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, o C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition on heating. On cooling, two exothermic peaks at o C (ΔH = kj mol -1 ) assigned 134

166 Heat flow (mw) to isotropic liquid-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-crystal transition. 4 3 Heating Cooling Temperature ( C) Figure 4.75 DSC scans of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Viewed under POM, the sample was observed to melt at 116 o C and to clear to an isotropic liquid phase at 190 o C. On cooling from the isotropic liquid phase, an optical texture was observed at 120 o C (Figure 4.76a). This texture coalesced on further cooling and became brighter at 118 o C (Figure 4.76b). (a) (b) Figure 4.76 Photomicrographs (on cooling) of [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O at: (a) 120 o C, and (b) 118 o C 135

167 Heat flow (mw) The DSC of 7 was recorded in the temperature range C. The scans (Figure 4.77) showed three endothermic peaks at 72.0 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, o C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition on heating. On cooling an exothermic peak at o C (ΔH = -4.0 kj mol -1 ) assigned to isotropic liquid-to-mesophase transition. 5 4 Heating Cooling Temperature ( C) Figure 4.77 DSC scans of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Viewed under POM, it was observed to melt at 98 o C and to clear to an isotropic liquid phase at 187 o C on heating. On cooling from this temperature an optical texture was observed at 135 o C (Figure 4.78). Hence, the complex was mesogenic. 136

168 Figure 4.78 Photomicrograph (on cooling) of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (7) at 135 o C (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2.2H 2 O a) Synthesis and structural elucidation Similar to complexes 6 and 7, [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2.2H 2 O (8) was prepared in a stepwise reaction as shown in Scheme CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H 5 was obtained as a white powder (Scheme 4.2). The yield was 87.8%. Its chemical formula, based on the elemental analyses, is C 23 H 38 O 3 (FW = 362.5g mol -1 ; Calc.: C, 76.20; H, 10.56%. Found: C, 76.65; H, 10.78%). Its 1 H-NMR spectrum (Figure 4.79) showed two doublets at 7.9 ppm and 6.8 ppm for the aromatic protons (H1, H2), a quartet at 4.3 ppm for two methylene protons (CH 3 CH 2 O-; H3), a triplet at 3.9 ppm for two methylene protons (CH 3 (CH 2 ) 12 CH 2 O-; H4), a multiplet at ppm for twenty six methylene protons (CH 3 (CH 2 ) 13 O-; H5), a triplet at 1.3 ppm for three methyl protons (CH 3 (CH 2 ) 13 O-; H6), and a triplet at 0.85 ppm for three methyl protons (CH 3 CH 2 O-; H7). 137

169 H6 H7 H1 H2 H3 H4 H5 Figure H-NMR spectrum of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H 5 Its FTIR spectrum (Figure 4.80) showed all of the expected functional groups (Table 4.13). Thus the elemental analyses, 1 H-NMR and FTIR results confirmed its structure as shown in Figure T% cm Figure 4.80 IR spectrum of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H 5 138

170 Table 4.13 FTIR data and assignments of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOC 2 H 5 and its corresponding metal complexes Compound Wavenumber, (cm -1 ) O-H N-H CH 2 C=O COO C-O C-N RCOOC 2 H s 1713s 1510s 1249s - (asym) 2849s (sym) (asym) 1314m (sym) RCOOK s m 1285s - (asym) 2851s (sym) (asym) 1424m (sym) [Cu 2 (RCOO) 4 (H 2 O) 2 ]. 3400br s s - - 2H 2 O (asym) 2851s (sym) (asym) 1434m (sym) br 3152m s (asym) 1377m (sym) m R= 4-CH 3 (CH 2 ) 13 OC 6 H 4, br, broad; s, strong; m, medium; w, weak. 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOK was obtained as a white powder (Scheme 4.2), and the yield was 84.4%. Its chemical formula, based on the elemental analyses, is C 21 H 33 KO 3 (FW = 372.5g mol -1 ; Calc.: C, 67.7; H, 8.9%. Found: C, 68.0; H, 9.0%). Its FTIR spectrum (Figure 4.81) showed all of the expected functional groups (Table 4.14). The value for the 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ion was 185 cm -1 [ ]. 139

171 T% cm -1 Figure 4.81 IR spectrum of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COOK [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was obtained as a blue powder and the yield was 59.5%. Its chemical formula, based on the elemental analyses, is C 84 H 140 Cu 2 O 16 (FW = g mol -1 ; Calc. C, 65.8; H, 9.2%. Found: C, 65.3; H, 9.0%). Its FTIR spectrum (Figure 4.82) showed the presence of all of the expected functional groups (Table 4.13). The value was 158 cm -1, suggesting bridging bidentate 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligand [79] T% cm -1 Figure 4.82 FTIR spectrum of [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 140

172 abs Its UV-vis spectrum (Figure 4.83) in CHCl 3 showed a broad d-d band at nm (ε max = M -1 cm -1 ) and a shoulder at about 370 nm, indicating a binuclear complex with square pyramidal geometry at Cu(II) [83, ] similar to [Cu 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (n = 9, 11) nm Figure 4.83 UV-vis spectrum of [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O The µ eff value, calculated from the values of FM = g mol -1, χ g = 2.3 x 10-6 cm 3 g -1, χ M = 4.5 x 10-3 cm 3 mol -1, and χ dia = -9.6 x 10-4 cm 3 mol -1 ), was 3.3 B.M. at 298 K. The value is higher than the spin-only value ( B.M) expected for square-pyramidal copper(ii) complexes [289, 290, 299, 300], as similarly observed for [Cu 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O and may be similarly described. Combining the instrumental data discussed above, its proposed structural formula was similar to [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (Figure 4.55). [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2.2H 2 O (8) was obtained as a purple powder (Scheme 4.2). The yield was 62.9%. Its chemical formula, based on the results of elemental analyses, is C 52 H 98 CuN 4 O 10 (FW = g mol -1 ; Calc.: C, 62.3; H, 9.85; N, 5.5%. Found: C, 62.5; H, 10.0; N, 5.47%). 141

173 abs Its FTIR spectrum (Figure 4.84) showed the presence of all of the expected functional groups (Table 4.14) and the Δ value was 172 cm -1, in agreement with non-coordinated 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO ions [ ], as similarly observed for 6 and T% cm -1 Figure 4.84 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.85) in CHCl 3 showed a broad d-d band at 545 nm (71.5 M -1 cm -1 ), suggesting a trans-iii octahedral geometry [282, 283], similar to 6 and nm Figure 4.85 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 142

174 Weight (%) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.2 x 10-6 cm 3 g -1, χ M = 1.2 x 10-3 cm 3 mol -1, and χ dia = -6.5 x 10-4 cm 3 mol -1, was 2.1 B.M. at 298 K. This is in agreement with a mononuclear Cu(II) in a distorted octahedral geometry ( B.M.) [ ], similar to 6 and 7. Combining these instrumental data discussed above, its proposed structural formula is similar to 6 (Figure 4.56a). b) Thermal behavior The TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (Figure 4.86) showed an initial weight loss of 2.3% of its mass from 108 o C to about 128 o C due to the evaporation of lattice H 2 O molecules (expected, 2.4%), followed by 3.1% from 245 o C to about 270 o C due to the evaporation of two coordinated H 2 O molecules (expected, 2.4%), 85.7% from 303 o C to about 583 o C due to the decomposition of the four 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands (expected, 87.0%), leaving 8.9% residue at temperatures above 583 o C (expected, 8.3% assuming CuO) [66, 291, 292]. The results is in agreement with its chemical formula, and its decomposition temperature (303 o C) was similar to [Cu 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (T dec = 300 and 307 o C for n = 9 and 11, respectively) Temperature ( C) Figure 4.86 TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O 143

175 Weight (%) The TGA trace for 8 (Figure 4.87) showed an initial weight loss of 3.4% (expected, 3.6%) from 70 o C to about 90 o C due to the evaporation of lattice H 2 O, followed by 85.2% (expected, 90.1%) from 263 o C to about 515 o C due to the evaporation of coordinated H 2 O, decomposition of cyclam ligand and 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ions, leaving 11.4% residue (expected, 6.6% assuming CuO) [66, 291, 292] at temperatures above 515 o C. Hence, the result is in agreement with its chemical formula and its thermal stability (T dec = 263 o C) was similar to 6 (T dec = 262 o C) and 7 (T dec = 265 o C). It might be concluded that alkyloxy chain lengths have insignificant effect on the thermal stability of these complexes Temperature ( C) Figure 4.87 TGA trace for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) c) Mesomorphic properties The DSC of [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was recorded in the temperature range C. The scans (Figure 4.88) showed two endothermic peaks at 98.3 o C ( H = kj mol -1 ) assigned to crystal-to-mesophase transition and o C ( H = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition on heating. On cooling two exothermic peaks at o C ( H = -1.4 kj mol -1 ) 144

176 Heat flow (mw) assigned to isotropic liquid-to-mesophase transition and 61.7 C (ΔH = kj mol -1 ) assigned to mesophase-to-crystal transition. 4 3 Heating Cooling Temperature ( C) Figure 4.88 DSC scans of [Cu 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Viewed under POM, the sample was observed to melt at about 120 o C and to clear to an isotropic liquid phase at 160 o C. On cooling from the isotropic liquid phase, an optical texture was observed at 126 o C. Its texture captured at o C is shown in Figure Figure 4.89 Photomicrograph (on cooling) of [Cu 2 (R) 4 (H 2 O) 2 ].2H 2 O at C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 145

177 Heat flow (mw) The DSC of 8 was recorded in the temperature range C. The scans (Figure 4.90) showed two strong endothermic peaks at o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition on heating. On cooling two exothermic peaks at o C (ΔH = kj mol -1 ) assigned to isotropic liquid-to-mesophase transition and 87.0 C (ΔH = kj mol -1 ) assigned to mesophase-to-crystal transition. 9 7 Heating Cooling Temperature ( C) Figure 4.90 DSC scans of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Viewed under POM, it was observed to melt at about 125 o C and to clear to an isotropic liquid phase at 143 o C. On cooling from isotropic liquid phase, an optical texture was observed at o C (Figure 4.91). Hence, the complex was mesogenic. Figure 4.91 Photomicrograph (on cooling) of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (8) at o C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 146

178 4.4.4 [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O a) Synthesis and structural elucidation Similar to complexes 6-8, [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O (9) was prepared in a stepwise reaction as shown in Scheme CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H 5 was obtained as a white powder (Scheme 4.2). The yield was 84.9%. Its chemical formula, based on elemental analyses, is C 25 H 42 O 3 (FW = g mol -1 ; Calc.: C, 76.8; H, 10.8%. Found: C, 76.7; H, 10.4%). Its 1 H-NMR spectrum (Figure 4.92) showed two doublets at 7.9 ppm and 6.8 ppm for the aromatic protons (H1, H2), a quartet at 4.3 ppm for two methylene protons (CH 3 CH 2 O-; H3), a multiplet at 3.9 ppm for two methylene protons (CH 3 (CH 2 ) 15 CH 2 O-; H4), a multiplet at 1.7 ppm for three methyl protons (CH 3 CH 2 O-; H5), a multiplet at ppm for thirty methylene protons (CH 3 (CH 2 ) 15 O-; H6), and a triplet at 0.83 ppm for three methyl protons (CH 3 (CH 2 ) 15 O-; H7). H6 H1 H2 H3 H4 H5 H7 Figure H-NMR spectrum of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H 5 Its FTIR spectrum (Figure 4.93) showed all of the expected functional groups (Table 4.14). Thus, the elemental analyses, 1 H-NMR and FTIR results confirmed its structure as shown in Figure

179 T% cm -1 Figure 4.93 FTIR spectrum of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H 5 Table 4.14 FTIR data and assignments of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOC 2 H 5 and its corresponding metal complexes Compound Wavenumber, (cm -1 ) O-H N-H CH 2 C=O COO C-O C-N RCOOC 2 H s 1714s 1510m 1249s - (asym) 2850s (sym) (asym) 1315m (sym) RCOOK s m 1285s - (asym) 2849s (sym) (asym) 1396m (sym) [Cu 2 (RCOO) 4 (H 2 O) 2 ] 3400br s m - -.2H 2 O (asym) 2849s (sym) (asym) 1435m (sym) m m (asym) 1476m (sym) m R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 ; br, broad; s, strong; m, medium; w, weak. 148

180 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOK was obtained as a white powder (Scheme 4.2) and the yield was 74.1%. Its chemical formula, based on elemental analyses, is C 23 H 37 KO 3 (FW = g mol -1 ; Calc.: C, 68.9; H, 9.3%. Found: C, 69.4; H, 10.1%). Its FTIR spectrum (Figure 4.94) showed all of the expected functional groups (Table 4.14). The value for the 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ion was 163 cm -1 [ ] T% cm -1 Figure 4.94 FTIR spectrum of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COOK [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was obtained as a blue powder and the yield was 61.0%. Its chemical formula, based on elemental analyses, is C 92 H 156 Cu 2 O 16 (FW = g mol -1 ; Calc. C, 67.2; H, 9.6%. Found: C, 67.8; H, 10.0%). Its FTIR spectrum (Figure 4.95) showed the presence of all of the expected functional groups (Table 4.15). The value was 158 cm -1, suggesting bridging bidentate 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligand [79]. 149

181 abs T% cm -1 Figure 4.95 FTIR spectrum of [Cu 2 (R) 4 (H 2 O) 2 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.96) in CHCl 3 showed a broad d-d band at 682 nm (388 M -1 cm -1 ) and a shoulder at about 370 nm, indicating a binuclear complex with square pyramidal geometry at Cu(II) [83, ] similar to [Cu 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (n = 9, 11, and 13) nm Figure 4.96 UV-vis spectrum of [Cu 2 (R) 4 (H 2 O) 2 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 150

182 The µ eff value, calculated from the values of FM = g mol -1, χ g = 1.4 x 10-6 cm 3 g -1, χ M = 3.4 x 10-3 cm 3 mol -1, and χ dia = -1.1 x 10-3 cm 3 mol -1, was 2.9 B.M. at 298 K. The value is higher than the spin-only value ( B.M) expected for square-pyramidal copper(ii) complexes [289, 290, 299, 300], as similarly observed for [Cu 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (n = 11 and 13). Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to [Cu 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (Figure 4.55). [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O (9) was obtained as purple crystals (Scheme 4.2). The yield was 61.6%. Its chemical formula, based on elemental analyses, was C 56 H 106 CuN 4 O 10 (FW = g mol -1 ; Calc.: C, 63.5; H, 10.1; N, 5.3%. Found: C, 65.9; H, 10.4; N, 5.4%). The complex (Figure 4.97a) crystallized in the triclinic system with the space group P -1. Crystal data and refinement details are given in Table 1 and selected bond lengths and angles are given in Table 4 in the APPENDIX A. Its single crystal X-ray structure (Figure 4.97) showed similar molecular structure as complex 7. The components of the crystallographic asymmetric unit were connected via O H...O hydrogen bonds whereby aqua and solvent water molecules bridged the carboxylate-o atoms. Each of the amine-n H atoms formed a N H...O hydrogen bond to a carboxylate-o atom with the result that three of the carboxylate-o atoms were bifurcated and the other trifurcated (Figure 4.97a). As the complex cations each lied on a centre of inversion, similar hydrogen bonds were formed on the other side of each CuN 4 plane leading to a supramolecular chain (Figure 4.97b). The chains aligned in the ab-plane with the carboxylate substituents lying to either side (Figure 4.97c). The only notable contact between chains was of the type C H

183 Figure 4.97 (a) Molecular view showing O H...O and N H...O hydrogen bonds between the components of the asymmetric unit of [Cu(cyclam)(H 2 O) 2 ] (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2.2H 2 O (9) and (b) supramolecular chain along [1-1 0]; most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity, and (c) a view in projection down the b-axis of the unit cell contents. The O H O and N H O hydrogen bond shown as orange and blue dashed lines respectively, lead to a chain. Colour code Cu, orange; O, red; N, blue; C, grey; and H, green 152

184 Table 4.15 Selected Hydrogen bonds for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) [Å and ] D-H...A d(d-h) d(h A) d(d...a) <(DHA) O1W-H1W1 O1 0.84(2) 1.93(2) 175(2) 170(4) O2W-H2W1 O1 0.84(2) 1.93(2) 172(2) 165(4) O3W-H3W1 O2 0.84(2) 1.96(2) 174(2) 169(4) O3W-H3W2 O4 0.83(2) 2.07(2) 2.900(2) 174(2) O1W-H1W2 O4 0.84(2) 2.00(2) 2.797(2) 158(2) O2W-H2W2 O5 0.83(2) 1.92(2) 2.735(3) 165(2) N1-H1 O (2) 2.134(2) 2.978(3) 150.4(1) N2-H2 O (2) 2.079(2) 2.987(3) 165.0(1) N3-H3 O3W 0.930(2) 2.045(2) 2.959(3) 167.2(1) N4-H4 O (2) 1.961(2) 2.888(2) 174.6(1) Its FTIR spectrum (Figure 4.98) showed the presence of all of the expected functional groups (Table 4.15). The Δ value was 170 cm -1, in agreement with non-coordinated 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ions [ ], as similarly observed for T% cm -1 Figure 4.98 FTIR spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 153

185 abs Its UV-vis spectrum (Figure 4.99) in CHCl 3 showed a broad d-d band at 546 nm (ε max = 86.2 M -1 cm -1 ), suggesting a trans- III octahedral geometry [282, 283] as revealed from its crystal structure and similarly observed for nm Figure 4.99 UV-vis spectrum of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.2 x 10-6 cm 3 g -1, χ M = 1.2 x 10-3 cm 3 mol -1, and χ dia = -7.1 x 10-4 cm 3 mol -1, was 2.2 B.M. at 298 K. This is in agreement with a mononuclear Cu(II) in a distorted octahedral geometry ( B.M.) [ ], similar to 6-8. The instrumental data discussed above supported its molecular structure revealed from its X-ray crystallography (Figure 4.97a). b) Thermal behavior The TGA trace (Figure 4.100) of [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O showed an initial weight loss of 2.4% from 107 o C to about 127 o C due to the evaporation of lattice H 2 O (expected, 2.2%), followed by 88.8% from 305 o C to about 577 o C due to the evaporation of coordinated H 2 O and decomposition of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO ligands (expected, 90.2%), leaving 8.8% residue at temperatures above 577 o C (expected, 7.7% assuming CuO) [66, 291, 292]. The result is in agreement with its chemical formula, and its decomposition temperature (305 o C) was 154

186 Weight (%) similar to that of [Cu 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (T dec = 300, 307 and 303 o C for n = 9, 11, and 13 respectively) Temperature ( C) Figure TGA trace for [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O The TGA trace (Figure 4.101) for 9 shows an initial weight loss of 2.3% (expected, 3.4%) from 67 o C to about 100 o C due to the evaporation of lattice H 2 O molecules, followed by 87.4% (expected, 90.6%) from 260 o C to about 500 o C due to the evaporation of coordinated H 2 O, and decomposition of cyclam and 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ion, leaving 10.3% residue (expected, 6.2%, assuming CuO) [66, 291, 292]. Hence, the result is in agreement with its chemical formula and its thermal stability (T dec = 260 o C) was similar to 6 (T dec = 262 o C), 7(T dec = 265 o C) and 8 (T dec = 263 o C). 155

187 Weight (%) Temperature ( C) Figure TGA trace for [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) c) Mesomorphic properties The DSC of [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O was recorded in the temperature range C. The scans (Figure 4.102) showed three endotherms on heating at 70.8 o C ( H = kj mol -1 ) assigned to crystal-to-mesophase transition, 98.3 o C ( H = kj mol -1 ) assigned to mesophase-to-mesophase transition, and o C ( H = kj mol -1 ) assigned to mesophase-to-isotropic liquid transition. On cooling, there were two exotherms at 140 o C ( H = kj mol -1 ) assigned to isotropic liquid-to-mesophase transition, and at 89.2 o C ( H = kj mol -1 ) assigned to mesophase-to-crystal transition. 156

188 Heat flow (mw) 4 3 Heating Cooling Temperature ( C) Figure DSC scans of [Cu 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O Viewed under POM, it was observed to melt at 74 o C and to clear to an isotropic liquid at o C. On cooling from isotropic liquid phase, a mesophase developed at o C (Figure 4.103a), which then crystallized at 83 o C (Figure 4.103b). These observations were in accord with DSC results. Hence, the complex was a mesogen. (a) (b) Figure Photomicrographs (on cooling) of [Cu 2 (R) 4 (H 2 O) 2 ].2H 2 O at: (a) C; and (b) 83.0 o C. (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) The DSC of 9 was recorded in the temperature range C. The scans (Figure 4.104) showed four endotherms on heating at 58.2 o C (ΔH = kj mol -1 ), 157

189 Heat flow (mw) assigned to the breaking of hydrogen bonds and van der Waals forces, 86.5 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, o C (ΔH = kj mol -1 ) assigned to the dissociation of coordinated H 2 O molecules, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid transition. The bond breaking and phase transitions were reversible as indicated by the almost coincident peaks on cooling the sample from the isotropic liquid phase Heating Cooling Temperature ( C) Figure DSC scans of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Under POM on heating it was observed to melt at 89 o C and to clear to an isotropic liquid at 145 o C. On cooling from the isotropic liquid phase, an optical texture was observed at 141 o C (Figure 4.105a), which coalesced on further cooling and became brighter at 89.9 o C when the sample crystallised (Figure 4.105b). These observations were in accord with the DSC results. 158

190 (a) (b) Figure Photomicrographs (on cooling) of [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O (9) at: (a) 141 C; and (b) 89.9 C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4.5 Concluding remarks [Cu 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O (n = 9, 11, 13 and 15) were dinuclear complexes with square pyramidal geometry at Cu(II) and obtained in good yields (52-67%). These complexes have magnetic susceptibilities in the range of B.M. and similar thermal stabilities (T dec = C), and were mesomorphic. [Cu 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 2 ].2H 2 O reacted with cyclam to form ionic mononuclear complexes, [Cu(cyclam)(H 2 O) 2 ](4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2.2H 2 O, in good yields (56-62%). These complexes have similar magnetic susceptibilities ( B.M.) and thermal stabilities (T dec = C), and were mesomorphic. 4.6 [Ni(cyclam)(4-ROC 6 H 4 COO) 2 ].2H 2 O [Ni(cyclam(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 )].2H 2 O a) Synthesis and structural elucidation [Ni(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (10) was prepared following similar procedure as shown in Scheme 4.2, replacing CuSO 4.5H 2 O in Step 3 with NiCl 2.6H 2 O. 159

191 [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] was obtained as a pale green powder and the yield was 56.6%. Its chemical formula, based on elemental analyses, is C 68 H 110 Ni 2 O 17 (FW = g mol -1 ; Calc. C, 62.0; H, 8.4%. Found: C, 62.8; H, 8.1%). Its FTIR spectrum (Figure 4.106) and data (Table 4.16 which also contains the data for complex 10 for later discussion), showed the presence of all of the expected functional groups. The values are 157 cm -1 and 204 cm -1, suggesting bridging bidentate [79] and monodentate [294] 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands respectively T% cm -1 Figure FTIR spectrum of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] Table 4.16 FTIR data and assignments of [Ni 2 (R) 4 (H 2 O) 5 ] and [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Ni 2 (R) 4 (H 2 O) 5 ] 3600br s (asym) 1599s, 1560s (asym) s (sym) 1395s, 1403s (sym) br 3281m 2923s (asym) 2855s (sym) 1593m (asym) 1379m (sym) 1101m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.107) in CHCl 3 showed three bands at 386 nm (ε max = 45.4 M -1 cm -1 ), 678 nm (ε max = 15.6 M -1 cm -1 ), and 1161 nm 160

192 abs (ε max = 10.8 M -1 cm -1 ), which attributed to the 3 A 2g 3 T 2g, 3 A 2g 3 T 1g (F), and 3 A 2g 3 T 1g (P) electronic transitions, respectively, indicating an octahedral geometry at Ni(II) atoms [ ] nm Figure UV-vis spectrum of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.2 x 10-5 cm 3 g -1, χ M = 1.5 x 10-2 cm 3 mol -1, and χ dia = -7.8 x 10-4 cm 3 mol -1, was 6.2 B.M. at 298 K. This was much larger than that 4.0 B.M. expected for two magnetically isolated Ni(II) ions with S = 1 [313, 314]. It might be inferred that there was a strong ferromagnetic interaction between Ni(II) centres. Combining the instrumental data discussed above, the proposed structural formula for the complex is [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.108) [315]. O R R O O O OH 2 H 2 O H 2 O Ni O O H 2 O Ni O OH 2 R R O Figure Schematic representation of the proposed structure of [Ni 2 (RCOO) 4 (H 2 O) 5 ] (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 ) 161

193 [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] reacted with cyclam (Step 4) to form [Ni(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (10). It was obtained as pink needles and its yield was 60.0%. Its chemical formula, based on elemental analyses, is C 44 H 78 NiN 4 O 8 (FW = g mol -1 ; Calc.: C, 62.2; H, 9.3; N, 6.6%. Found: C, 62.2; H, 9.9; N, 6.6%). The complex (Figure 4.109a) crystallized in the monoclinic system with the space group P 2 1 /c. Crystal data and refinement details are given in Table 2 and selected bond lengths and angles are given in Table 4 in the APPENDIX A. Its single crystal X-ray crystallography showed similar centrosymmetric and octahedral trans- N 4 O 2 donor set [Ni N1 = 2.071(3) Å, Ni N2 = 2.062(2) Å and Ni O1 = 2.096(2) Å] and axial elongation due to Jahn-Teller distortion, as similarly found for [Cu(cyclam)(H 2 O) 2 ](4-FC 6 H 4 COO) 2 (Figure 4.109a). The difference between the two complexes was that two trans-o atoms in Ni(II) complex were derived from the coordinating 4-decyloxybenzoate ligands (the ligands were directly coordinated to the Ni(II) atom). Only two types of hydrogen bonding were apparent in the crystal structure (Table 4.17). The second O2 atom of the carboxylate ligand was hydrogen bonded to the amine N2-H of the complex cation and to solvent water O1W-H1W to form intramolecular hydrogen bonds. Thus, each O2 atom of carboxylate ligand was bifurcated. There were no intermolecular hydrogen bonds. Table 4.17 Hydrogen bonds for [Ni(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (10) [Å and ] D-H A d(d-h) d(h...a) d(d...a) <(DHA) O1W-H1W1 O (3) 1.940(3) 2.803(4) 162.9(2) N2-H2 O (3) 2.218(3) 3.010(4) 145.2(2) 162

194 (a) (b) Figure (a) Molecular view, showing displacement ellipsoids at 50% probability level; and (b) packing diagram of [Ni(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (10); operator used to generate symmetry equivalent elements: -x+1, -y+1, -z. Colour code: Ni, green; O, red; N, blue; and C, grey Its FTIR spectrum (Figure 4.110) showed the presence of all of the expected functional groups (Table 4.16). The Δ value was 214 cm -1, in agreement with monodentate 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands [294] as revealed from its crystal structure. 163

195 abs T% cm -1 Figure FTIR spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.111) in CHCl 3 showed a broad d-d band at 515 nm (ε max = 13.8 M -1 cm -1 ), suggesting a trans-iii octahedral geometry around Ni(II) [ ], as revealed from its crystal structure nm Figure UV-vis spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) It is noted that there was only one band in the spectrum of 10, while there were three bands in the spectrum of its precursor complex, 164

196 [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ]. This arose from the difference in the field strength of the ligands. The Ni(II) atom in 10 was surrounded by four N atom from cyclam and two O atoms from the carboxylate ligands (NiN 4 O 2 chromophore; Figure 4.109). In contrast, the Ni(II) atom in its precursor was surrounded by six O atoms from three carboxylate and three H 2 O ligands (NiO 6 chromophore; Figure 4.108). The stronger ligand field strength in 10 resulted in hypsochromic shift (blue shift) of the d-d bands. As a result, the higher energy transitions became hidden under the strong charge-transfer bands. Its µ eff value, calculated from the values of FM = g mol -1, χ g = 0.4 x 10-5 cm 3 g -1, χ M = 3.4 x 10-3 cm 3 mol -1, and χ dia = -5.3 x 10-4 cm 3 mol -1, was 3.1 B.M. at 298 K. This is in agreement with a mononuclear Ni(II) in an octahedral geometry ( B.M.) [316]. b) Thermal behavior The TGA trace of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.112) showed an initial weight loss of 90.9% (expected, 91.1%) from 258 o C to about 531 o C due to the evaporation of coordinated H 2 O and the decomposition of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, leaving 9.1% residue (expected 8.9%, assuming NiO) [292, 317, 318]. The result is in agreement with its chemical formula, and its decomposition temperature was 258 o C. 165

197 Weight (%) Weight (%) Temperature ( C) Figure TGA trace for [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] The TGA trace of 10 (Figure 4.113) showed an initial weight loss of 3% (expected, 4.2%) from 77 o C to about 113 o C due to the evaporation of lattice H 2 O, followed by 87.8% (expected, 88.8%) from 256 o C to about 500 o C due to the decomposition of cyclam and 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, leaving 9.2% residue (expected 7.0%, assuming NiO) [292, 317, 318]. The result is in agreement with its chemical formula, and its decomposition temperature was 256 o C, similar to its dimeric precursor [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (T dec = 258 o C) Temperature ( C) Figure TGA trace for [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 166

198 Heat flow (mw) c) Mesomorphic properties The DSC of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] was recorded in the temperature range C. The scans (Figure 4.114) showed a broad endothermic peak on heating at o C (ΔH = kj mol -1 ), but no peaks on cooling. It did not exhibit any optical textures when viewed under POM. Hence, it was not mesogenic. 3 Heating Cooling Temperature ( C) Figure DSC scans of [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] The DSC scans for 10 (Figure 4.115), recorded in the temperature range C, showed endothermic peaks at 70.8 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase, and o C (ΔH = kj mol -1 ) assigned to mesophase-toisotropic liquid phase transition on heating, and an exothermic peak at 95.8 o C (ΔH = -1.3 kj mol -1 ) assigned to isotropic liquid-to-mesophase transition on cooling. 167

199 Heat flow (mw) 5 4 Heating Cooling Temperature ( C) Figure DSC scans of [Ni(cyclam)(R) 2 ].2H 2 O (10) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Viewed under POM, it was observed to melt at 70 o C and to clear to an isotropic liquid at o C. On cooling from isotropic liquid phase, a mesophase developed at 100 o C (Figure 4.116a). These observations were in accord with DSC results. Hence, the complex was a mesogen. Figure Photomicrograph of [Ni(cyclam)(R) 2 ].2H 2 O (10) on cooling at 100 o C (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) [Ni(cyclam(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 )].2H 2 O a) Synthesis and structural elucidation Similar to complex 10, [Ni(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (11) was prepared following similar procedure as shown in Scheme

200 [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] was obtained as a pale green powder and the yield was 54.1%. Its chemical formula, based on the elemental analyses, is C 76 H 126 Ni 2 O 17 (FW = g mol -1 ; Calc. C, 63.9; H, 8.9%. Found: C, 63.8; H, 8.7%). Its FTIR spectrum (Figure 4.117) showed the presence of all of the expected functional groups (Table 4.18). The Δ values were 158 cm -1 and 204 cm -1, suggesting bridging bidentate [79] and monodentate [294] 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, respectively T% cm -1 Figure FTIR spectrum of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] Table 4.18 FTIR data and assignments of [Ni 2 (R) 4 (H 2 O) 5 ] and [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Ni 2 (RCOO) 4 (H 2 O) 5 ] 3600br s (asym) 1599s, 1562s (asym) s (sym) 1395s, 1404s (sym) br 3186m 2923s (asym) 2854s (sym) 1592m(asym) 1379m (sym) 1101m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.118) in CHCl 3 showed three bands at 386 nm (ε max = 52.2 M -1 cm -1 ), 674 nm (ε max = 18.8 M -1 cm -1 ), and 1188 nm 169

201 abs (ε max = 14.4 M -1 cm -1 ), indicating an octahedral geometry at Ni(II) atoms [ ], similarly observed for [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] nm Figure UV-vis spectrum of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] The µ eff value, calculated from the values of FM = g mol -1, χ g = 9.9 x 10-6 cm 3 g -1, χ M = 1.4 x 10-2 cm 3 mol -1, and χ dia = -8.8 x 10-4 cm 3 mol -1, was 6.0 B.M. at 298 K. This was significantly larger than that 4.0 B.M expected for two magnetically isolated Ni(II) ions with S = 1 [313, 314]. It might be inferred that there was a strong ferromagnetic interaction between Ni(II) centres. Combining the instrumental data discussed above, the proposed structural formula for the complex is similar to [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.108) [315]. [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] reacted with cyclam to form [Ni(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (11). It was obtained as pink needles and its yield was 60.0%. Its chemical formula, based on the elemental analyses, was C 48 H 86 N 4 NiO 8 (FW = g mol -1 ; Calc.: C, 63.6; H, 9.6; N, 6.2%. Found: C, 63.7; H, 9.9; N, 6.3%). 170

202 The complex (Figure 4.119a) crystallized in the monoclinic system with the space group P 2 1 /c. Crystal data and refinement details are given in Table 2 and selected bond lengths and angles are given in Table 4 in the APPENDIX A. Its single crystal X-ray crystallography showed centrosymmetric and octahedral trans-n 4 O 2 donor set [Ni N1 = 2.078(4) Å, Ni N2 = 2.076(4) Å and Ni O1 = 2.094(3) Å] and axial elongation due to Jahn-Teller distortion, as similarly found for 10 (Figure 4.119a). In addition, 4-dodecyloxybenzoate ions were directly coordinated to the Ni(II) atom, and similar types of hydrogen bonding as found for 10 were observed in its crystal structure (Table 4.19). Table 4.19 Selected Hydrogen bonds for [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Å and ] D-H...A d(d-h) d(h...a) d(d...a) <(DHA) O1W-H1 O2 0.8(1) 2.0(1) 2.817(6) N1-H1 O (4) 2.218(3) 3.020(5) 164(10) 143.7(3) 171

203 (a) (b) Figure (a) Molecular view, showing displacement ellipsoids at 50% probability level; (b) packing diagram of [Ni(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (11) along crystallographic b-axis; operator used to generate symmetry equivalent elements: -x+1, -y+1, -z. Colour code: same as in Figure Its FTIR spectrum (Figure 4.120) showed the values of all of the expected functional groups (Table 4.18). The Δ value was 213 cm -1, in agreement with monodentate 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands [294] as revealed from its crystal structure. 172

204 abs T% cm Figure FTIR spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.121) in CHCl 3 showed a broad d-d band at 511 nm (ε max = 11.5 M -1 cm -1 ), suggesting a trans-iii octahedral geometry [ ] as revealed from its crystal structure nm Figure UV-vis spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 2.9 x 10-6 cm 3 g -1, χ M = 2.7 x 10-3 cm 3 mol -1, and χ dia = -5.8 x 10-4 cm 3 mol -1, was 2.8 B.M at 298 K. This is in agreement with a mononuclear Ni(II) in an octahedral geometry ( B.M.) [316] as similarly observed for

205 Weight (%) b) Thermal behavior The TGA trace of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.122) showed an initial weight loss of 90.6% (expected, 91.8%) from 258 o C to about 596 o C due to the evaporation of H 2 O molecules and the decomposition of CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, leaving 9.4% residue at temperatures above 596 o C (expected 8.2%, assuming NiO) [292, 317, 318]. The result is in agreement with its chemical formula, and its decomposition temperature was 258 o C similar to [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (T dec = 258 o C) Temperature ( C) Figure TGA trace for [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] The TGA trace of 11 (Figure 4.123) showed an initial weight loss of 4.0% (expected, 4.0%) from 81 o C to about 108 o C due to the evaporation of lattice H 2 O, followed by 89.3% (expected, 89.5%) from 258 o C to about 460 o C due to the decomposition of cyclam and 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, leaving 6.7% residue at temperatures above 460 o C (expected, 6.5%, assuming NiO) [292, 317, 318]. The result is in agreement with its chemical formula, and its decomposition temperature was 258 o C, similar to 10 (T dec = 256 o C). 174

206 Heat flow (mw) Weight (%) Temperature ( C) Figure TGA trace for [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) c) Mesomorphic properties The DSC of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ] was recorded in the temperature range C. The scans (Figure 4.124) showed a broad endotherm on heating at o C (ΔH = kj mol -1 ) on heating, but no peaks on cooling. It did not exhibit any optical textures when viewed under POM. Hence, it was not mesogenic Heating Cooling Temperature ( C) Figure DSC scans of [Ni 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] The DSC scans for 11 (Figure 4.125), recorded in the temperature range C, showed endothermic peaks at 71.0 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, and at o C (ΔH = kj mol -1 ) assigned to 175

207 Heat flow (mw) mesophase-to-isotropic liquid phase transition on heating, and exothermic peaks at 74.8 o C (ΔH = kj mol -1 ) assigned to isotropic liquid-to-mesophase transition and at 44.2 o C (ΔH = -3.7 kj mol -1 ) assigned to mesophase-to-mesophase transition on cooling Heating Cooling Temperature ( C) Figure DSC scans of [Ni(cyclam)(R) 2 ].2H 2 O (11) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Viewed under POM, it was observed to melt at 76.9 o C and to clear to an isotropic liquid at 111 o C. On cooling from isotropic liquid phase, a mesophase developed at o C (Figure 4.126a) that coalesced on further cooling and became brighter at 51.3 o C (Figure 4.126b). These observations were in accord with DSC results. Hence, the complex was a mesogen. (a) (b) Figure Photomicrographs of [Ni(cyclam)(R) 2 ].2H 2 O (11) on cooling at: (a) o C; and (b) 51.3 o C (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 176

208 4.6.3 [Ni(cyclam(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 )].2H 2 O (a) Synthesis and structural elucidation Similar to complexes 10 and 11, [Ni(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O (12) was prepared following similar procedure as shown in Scheme 4.2. [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O was obtained as a pale green powder and the yield was 51.5%. Its chemical formula, based on the results of elemental analyses, is C 84 H 144 Ni 2 O 18 (FW = g mol -1 ; Calc. C, 64.7; H, 9.3%. Found: C, 65.1; H, 9.9%). Its FTIR spectrum (Figure 4.127) showed the presence of all of the expected functional groups (Table 4.20). The Δ values are 152 cm -1 and 202 cm -1, suggesting bridging bidentate [79] and monodentate [294] 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands, respectively T% cm -1 Figure FTIR spectrum of [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O 177

209 abs Table 4.20 FTIR data and assignments of [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O and [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O 3600br s (asym) 2851s (sym) br 3188m 2921s (asym) 2853s (sym) br, broad; s, strong; m, medium; w, weak. 1598s (asym) 1446s, 1396s (sym) 1592m (asym) 1378m (sym) m Its UV-vis spectrum (Figure 4.128) in CHCl 3 showed three bands at 387 nm (54.7 M -1 cm -1 ), 676 nm (18.5 M -1 cm -1 ), and 1163 nm (12.7M -1 cm -1 ), indicating octahedral geometry around Ni(II) ion similar to [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] nm Figure UV- vis spectrum of [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 4.6 x 10-6 cm 3 g -1, χ M = 7.1 x 10-3 cm 3 mol -1, and χ dia = -9.9 x 10-4 cm 3 mol -1, was 4.4 B.M. at 298 K. This was in agreement with the expected value of 4.0 B.M. for two magnetically isolated Ni(II) ions (S = 1) [313, 314]. It might be inferred that there was insignificant magnetic interaction between the two Ni(II) centres. 178

210 Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.108) [315]. [Ni(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O (12) was obtained as a pink powder (Scheme 4.2), and the yield was 54.2%. Its chemical formula, based on the results of the elemental analyses, is C 52 H 94 N 4 NiO 8 (FW = g mol -1 ; Calc.: C, 64.9; H, 9.6; N, 5.8%. Found: C, 64.8; H, 10.0; N, 5.6%). Its FTIR spectrum (Figure 4.129) showed the presence of all of the expected functional groups (Table 4.20). The Δ value is 214 cm -1, in agreement with monodentate 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands [294]. 95 T% cm -1 Figure FTIR spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.130) in CHCl 3 showed a broad d-d band at 505 nm (ε max = 13.9 M -1 cm -1 ), suggesting a trans-iii octahedral geometry [ ], similar to complexes 10 and

211 abs nm Figure UV-vis spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 0.4 x 10-5 cm 3 g -1, χ M = 3.7 x 10-3 cm 3 mol -1, and χ dia = -6.2 x 10-4 cm 3 mol -1 ), was 3.2 B.M at 298 K. This is in agreement with a mononuclear Ni(II) octahedral complex ( B.M.) [316], as similarly observed for 10 and 11. Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to 10 (Figure 4.109a). (b) Thermal behavior The TGA trace of [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O (Figure 4.131) showed an initial weight loss of 1.4% (expected, 1.2%) from 84 o C to about 121 o C due to the evaporation of lattice H 2 O, 91.6% (expected, 91.3%) from 276 o C to about 592 o C due to the evaporation of coordinated H 2 O and decomposition of CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands, leaving 7.0% residue (expected 7.5%, assuming NiO) [292, 317, 318]. The result is in agreement with its chemical formula, and its thermal stability (T dec = 276 o C) was slightly higher than [Ni 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (T dec = 258 o C for n = 9 and 11 both). 180

212 Weight (%) Weight (%) Temperature ( C) Figure TGA trace for [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O The TGA trace of 12 (Figure 4.132) showed an initial weight loss of 2.7% (expected, 3.8%) from 87 o C to about 111 o C due to the evaporation of H 2 O, followed by 88.9% (expected, 90.2%) from 286 o C to about 508 o C due to the decomposition of cyclam and 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands, leaving 8.4% residue (expected, 6.0%, assuming NiO) [292, 217, 218]. The result is in agreement with its chemical formula, and its decomposition temperature was 286 o C. Thus, its thermal stability was higher than 10 (T dec = 256 o C) and 11 (T dec = 258 o C) Temperature ( C) Figure TGA trace for [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 181

213 Heat flow (mw) c) Mesomorphic properties The DSC of [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O was recorded in the temperature range C. The scans (Figure 4.133) showed three endothermic peaks on heating at 89.2 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, o C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition, and o C (ΔH = +7.4 kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition, and two exothermic peaks at o C (ΔH = kj mol -1 ) assigned to isotropic liquid-to-mesophase transition, and at 89.2 o C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition, respectively, on cooling Heating Cooling Temperature ( C) Figure DSC scans of [Ni 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] Viewed under POM, it was observed to melt at 118 o C and to clear at o C. On cooling from this temperature, an optical texture was observed at o C (Figure 4.134a) which coalesced on further cooling at o C (Figure 4.134b). 182

214 Heat flow (mw) (a) (b) Figure Photomicrographs (on cooling) of [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O at: (a) o C, and (b)129.8 o C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) The DSC scans for 12 (Figure 4.135), recorded in the temperature range C, showed endothermic peaks at o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition on heating, and an exothermic peak at o C (ΔH = kj mol -1 ) assigned to isotropic liquid-to-mesophase transition on cooling. 3 2 Heating Cooling Temperature ( C) Figure DSC scans of [Ni(cyclam)(R) 2 ].2H 2 O (12) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 183

215 Viewed under POM, it was observed to melt at 95 o C and to clear to an isotropic liquid at 108 o C. On cooling from isotropic liquid phase, a mesophase developed at 47.7 o C (Figure 4.136a) that coalesced when the temperature was kept on hold for 3 min (Figure 4.136b). These observations were in accord with DSC results and the complex was a mesogen. (a) (b) Figure Photomicrographs (on cooling) of [Ni(cyclam)(R) 2 ].2H 2 O (12) at 47.7 o C: (a) initial time; and (b) after 3 min (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO [Ni(cyclam(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 )].2H 2 O a) Synthesis and structural elucidation Similar to complexes 10-12, [Ni(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O (13) was prepared following similar procedure as shown in Scheme 4.2. [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O was obtained as a pale green powder and the yield was 68.1%. Its chemical formula, based on the results of elemental analyses, is C 92 H 160 Ni 2 O 18 (FW = g mol -1 ; Calc. C, 66.1; H, 9.7%. Found: C, 66.4; H, 10.0%). Its FTIR spectrum (Figure 4.137) showed the presence of all of the expected functional groups (Table 4.21). The Δ values were 141 cm -1 and 201 cm -1, suggesting bridging bidentate [79] and monodentate [294] 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - respectively. ligands, 184

216 99 T% cm -1 Figure FTIR spectrum of [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O Table 4.21 FTIR data and assignments of [Ni 2 (R) 4 (H 2 O) 5 ] H 2 O and [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Ni 2 (R) 4 (H 2 O) 5 ] 3600br s (asym) 1599s, 1563m (asym) s (sym) 1398m, 1422m (sym) br 3186m 2921s (asym) 2852s (sym) 1593m (asym) 1379m (sym) 1101m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.138) in CHCl 3 exhibited three bands at 386 nm (50.5 M -1 cm -1 ), 671 nm (17.7 M -1 cm -1 ), and 1184 nm (13.4 M -1 cm -1 ), indicating octahedral geometry around Ni(II) ion similar to [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ]. 185

217 abs nm Figure UV-vis spectrum of [Ni 2 (R) 4 (H 2 O) 5 ].H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) The µ eff value, calculated from the values of FM = g mol -1, χ g = 5.4 x 10-6 cm 3 g -1, χ M = 9.0 x 10-3 cm 3 mol -1, and χ dia = -1.1 x 10-3 cm 3 mol -1, was 4.9 B.M. at 298 K. This was in agreement with the expected value of 4.0 B.M. for two magnetically isolated Ni(II) ions (S = 1) [313, 314]. It might be inferred that there was insignificant magnetic interaction between the two Ni(II) centres. Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to [Ni 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.108) [315]. [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O reacted with cyclam to form [Ni(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O (13). It was obtained as a pink powder and its yield was 71.4%. Its chemical formula, based on the results of elemental analyses, is C 56 H 102 N 4 NiO 8 (FW = g mol -1 ; Calc.: C, 66.1; H, 10.1; N, 5.5%. Found: C, 66.2; H, 10.6; N, 5.3%). Its FTIR spectrum (Figure 4.139) showed the presence of all of the expected functional groups (Table 4.21). The Δ value was 214 cm -1, in agreement with monodentate 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligands [294]. 186

218 abs T% cm Figure FTIR spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.140) in CHCl 3 showed a broad d-d band at 516 nm (ε max = 9.9 M -1 cm -1 ), suggesting a trans-iii octahedral geometry [ ], similar to complexes nm Figure UV-vis spectrum of [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 0.3 x 10-5 cm 3 g -1, χ M = 2.7 x 10-3 cm 3 mol -1, and χ dia = -6.8 x 10-4 cm 3 mol -1, was 187

219 Weight (%) 2.9 B.M. at 298 K. This is in agreement with a mononuclear Ni(II) octahedral complex ( B.M.) [316], as similarly observed for 10, 11, and 12. Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to 10 (Figure 4.109a). b) Thermal behavior The TGA trace of [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].H 2 O (Figure 4.141) showed an initial weight loss of 1.0% (expected, 1.1%) from 50 o C to about 118 o C due to the evaporation of lattice H 2 O, followed by 89.1% (expected, 91.9%) from 272 o C to about 596 o C due to the evaporation of coordinated H 2 O and decomposition of CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligands, leaving 9.9% residue at temperatures above 596 o C (expected 7.0%, assuming NiO) [292, 317, 318]. The result is in agreement with its chemical formula, and its thermal stability (T dec = 272 o C) was similar to [Ni 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (T dec = 276 o C for n = 13), and slightly higher than n = 9 and 11 (T dec = 258 o C for both) Temperature ( C) Figure TGA trace for [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ] 188

220 Weight (%) The TGA trace of 13 (Figure 4.142) showed an initial weight loss of 2.7% (expected, 3.5%) from 88 o C to about 108 o C due to the evaporation of lattice H 2 O, followed by 91.3% (expected, 90.7%) from 261 o C to about 453 o C due to the decomposition of cyclam and 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligands, leaving 6.0% residue at temperatures above 453 o C (expected, 5.8%, assuming NiO) [292, 317, 318]. The result is in agreement with its chemical formula, and its decomposition temperature was 261 o C. Thus, its thermal stability was similar to 10 (T dec = 256 o C) and 11 (T dec = 258 o C), but lower than 12 (T dec = 286 o C) Temperature ( C) Figure TGA trace for [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) c) Mesomorphic properties The DSC of [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ] was recorded in the temperature range C. The scans (Figure 4.143) showed four endotherms on heating at 89.2 o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds and van der Waals forces, o C (ΔH = kj mol -1 ) assigned to dissociation of coordinated H 2 O molecules, o C (ΔH = kj mol -1 ) assigned to its melting temperature, and o C (ΔH = kj mol -1 ) assigned to its clearing temperature. On cooling, there was an exotherm at 98.3 o C (ΔH = kj mol -1 ) assigned to the formation of hydrogen 189

221 Heat flow (mw) Heat flow (mw) bonds and van der Waals forces. Viewed under POM it was observed to melt at 109 o C, but no optical textures was observed on cooling from 160 o C. Hence, it was not mesogenic. 6 Heating Cooling Temperature ( C) Figure DSC scans of [Ni 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ] The DSC scans for 13 (Figure 4.144), recorded in the temperature range C, showed two endotherms at 76.3 o C (ΔH = kj mol -1 ) assigned crystal-to-mesophase transition, and at o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid transition. On cooling, there was a weak exotherm at 102 o C (ΔH = kj mol -1 ) assigned to the isotropic liquid-to-mesophase transition Heating Cooling Temperature ( C) Figure DSC scans of [Ni(cyclam)(R) 2 ].2H 2 O (13) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 190

222 Viewed under POM, it was observed to melt at 93.0 o C and to clear to an isotropic liquid at o C. On cooling from the isotropic liquid phase, an optical texture was observed at 88.6 o C (Figure 4.145). Hence, the complex was mesogenic. Figure Photomicrograph (on cooling) of [Ni(cyclam)(R) 2 ].2H 2 O (13) at 88.6 o C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4.7 Concluding remarks [Ni 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (n = 9, 11, 13 and 15) were obtained in good yields (51-68%). These complexes were binuclear with octahedral geometry at Ni(II), have magnetic susceptibilities in the range of B.M., and were thermally stable (T dec = C). They reacted with cyclam to form covalent mononuclear complexes, [Ni(cyclam)(4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2 ].2H 2 O, in good yields (54-71%). The latter complexes have similar magnetic susceptibilities ( B.M.) and thermal stabilities (T dec = C), and were mesogenic. 4.8 [Co(cyclam)(4-ROC 6 H 4 COO) 2 ].2H 2 O [Co(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 )].2H 2 O a) Synthesis and structural elucidation [Co(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (14) was prepared following similar procedure as shown in Scheme 4.2, replacing CuSO 4.5H 2 O in step 3 with CoCl 2.6H 2 O. 191

223 [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] was obtained as a pale purple powder and the yield was 72.7%. Its chemical formula, based on the results of elemental analyses, is C 68 H 110 Co 2 O 17 (FW = g mol -1 ; Calc. C, 61.9; H, 8.4%. Found: C, 60.7; H, 8.0%). Its FTIR spectrum (Figure 4.146) showed the presence of all of the expected functional groups (Table 4.22). The Δ values are 139 cm -1 and 210 cm -1, suggesting bidentate bridging [79] and monodentate [294] 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, respectively T% cm -1 Figure FTIR spectrum of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] Table 4.22 FTIR data and assignments of [Co 2 (R) 4 (H 2 O) 5 ] and [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Co 2 (R) 4 (H 2 O) 5 ] 3600m s (asym) 1599s (asym) s (sym) 1420s, 1389s (sym) br 3180m m (asym) 1342m (sym) 1100m br, broad; s, strong; m, medium; w, weak. 192

224 abs Its UV-vis spectrum (Figure 4.147) in THF showed a broad d-d band at nm (ε max = M -1 cm -1 ) suggesting an octahedral geometry at Co(II) [319, 320] nm Figure UV-vis spectrum of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] Its µ eff value, calculated from the values of FM = g mol -1, χ g = 2.2 x 10-5 cm 3 g -1, χ M = 2.9 x 10-2 cm 3 mol -1, and χ dia = -7.8 x 10-4 cm 3 mol -1, was 8.4 B.M. at 298 K. This is significantly higher than the expected value of 5.5 B.M. for two magnetically isolated Co(II) ions (S = 3/2) [157, 321]. It may be inferred from this that there was a strong ferromagnetic interaction between the Co(II) centres in this complex. Combining the instrumental data discussed above, the proposed structural formula for the complex was [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.148) [187]. O R R O O O OH 2 H 2 O H 2 O Co O O H 2 O Co O OH 2 R R O Figure Schematic representation of the proposed structure of [Co 2 (4-RCOO) 4 (H 2 O) 5 ] (R = CH 3 (CH 2 ) 9 OC 6 H 4 ) 193

225 [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] reacted with cyclam to form [Co(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O (14). The product was a purple powder and its yield was 72.7%. Its chemical formula, based on the results of elemental analyses, is C 44 H 78 NiN 4 O 8 (FW = g mol -1 ; Calc.: C, 62.2; H, 9.3; N, 6.6%. Found: C, 62.3; H, 9.6; N, 6.6%). Its FTIR spectrum (Figure 4.149) showed the presence of all of the expected functional groups (Table 4.22). The Δ value was 229 cm -1, suggesting monodentate 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands [294] T% cm -1 Figure FTIR spectrum of [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.150) in CHCl 3 showed two bands at 563 nm (ε max = 26.4 M -1 cm -1 ) and 444 nm (ε max = 22.4 M -1 cm -1 ) assigned to 4 T 1g (F) 4 A 2g (F) and 4 T 1g (F) 4 T 1g (P) transitions, respectively. The result suggested a trans-iii octahedral geometry for the complex [319, 320]. 194

226 abs nm Figure UV-vis spectrum of [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.1 x 10-5 cm 3 g -1, χ M = 8.9 x 10-3 cm 3 mol -1, and χ dia = -5.3 x 10-4 cm 3 mol -1 ), was 4.8 B.M. at 298 K. This is in agreement with a mononuclear Co(II) octahedral complex ( B.M.) [319, 322, 323]. Based on UV-visible and magnetic results, it is proposed that structural formula of [Co(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].2H 2 O is as shown in Figure RO O O N N Co N N O O OR Figure Proposed structure of [Co(cyclam)(4-ROC 6 H 4 COO) 2 ].2H 2 O (14) (R = CH 3 (CH 2 ) 9 ); lattice H 2 O are not shown b) Thermal behavior The TGA trace of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.152) showed an initial weight loss of 1.4% (expected, 1.4%) from 200 o C to about 268 o C due to the evaporation of bridging H 2 O, followed by 89.7% (expected, 89.7%) from 300 o C to about 500 o C due to the evaporation of H 2 O molecules and decomposition of 195

227 Weight (%) CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, leaving 8.9% residue at temperatures above 500 o C (expected 8.9%, assuming CoO) [292]. The result is in agreement with its chemical formula, and its decomposition temperature was 300 o C Temperature ( C) Figure TGA trace for [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] The TGA trace of 14 (Figure 4.153) showed an initial weight loss of 5% (expected, 4.2%) from 50 o C to about 150 o C due to evaporation of lattice H 2 O, followed by 85.5% (expected, 88.8%) from 229 o C to about 612 o C due to the decomposition of cyclam and CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, leaving 9.5% residue at temperatures above 612 o C (expected, 7.0%, assuming CoO) [292]. The result is in agreement with its chemical formula, and its decomposition temperature was 229 o C. Thus, the complex was thermally less stable compared to its precursor, [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (T dec = 300 o C). 196

228 Heat flow (mw) Weight (%) Temperature ( C) Figure TGA trace for [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) c) Mesomorphic properties The DSC of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] was recorded in the temperature range C. The scans (Figure 4.154) showed, on heating, two endotherms at o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds and van der Waals forces, and o C (ΔH = kj mol -1 ) assigned to its clearing temperature. On cooling, there was an exotherm at 56.0 o C (ΔH = kj mol -1 ) assigned to the formation of hydrogen bonds and van der Waals forces. Viewed under POM, it was observed to melt at 110 o C, but no optical texture was observed on cooling from 225 o C. Hence, the complex was not mesogenic. 3 2 Heating Cooling Temperature ( C) Figure DSC scans of [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] 197

229 Heat flow (mw) The DSC scans for 14 (Figure 4.155), recorded in the temperature range C, showed on heating, three endotherms at 54.0 o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds, 78.2 o C (ΔH = kj mol -1 ) assigned to its crystal-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to its mesophase-to-isotropic liquid phase transition. On cooling, there was an exotherm at o C (ΔH = -0.2 kj mol -1 ) assigned to the isotropic liquid-to-mesophase transition. 4 3 Heating Cooling Temperature ( C) Figure DSC scans of [Co(cyclam)(R) 2 ].2H 2 O (14) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Viewed under POM, it was observed to melt at 80 o C and to clear to an isotropic liquid phase at 138 o C. On cooling from the isotropic liquid phase, an optical texture was observed at o C (Figure 4.156a), which then coalesced at 97.3 o C (Figure 4.156b) on further cooling. Hence, the complex was mesogenic. (a) (b) Figure Photomicrographs (on cooling) of [Co(cyclam)(R) 2 ].2H 2 O (14) at: (a) o C; and (b) 97.3 o C (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 198

230 4.8.2 [Co(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 )].2H 2 O a) Synthesis and structural elucidation Similar to 14, [Co(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (15) was prepared following the procedure as shown in Scheme 4.2. [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] was obtained as a pale purple powder and the yield was 56.7%. Its chemical formula, based on the results of elemental analyses, is C 76 H 126 Co 2 O 17 (FW = g mol -1 ; Calc. C, 63.9; H, 8.9%. Found: C, 63.6; H, 8.6%). Its FTIR spectrum (Figure 4.157) showed the presence of all of the expected functional groups (Table 4.23). The Δ values were 139 cm -1 and 210 cm -1, suggesting bridging bidentate [79] and monodentate [294] 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, respectively T% cm -1 Figure FTIR spectrum of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] 199

231 abs Table 4.23 FTIR data and assignments of [Co 2 (R) 4 (H 2 O) 5 ] and [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Co 2 (R) 4 (H 2 O) 5 ] 3600br s (asym) 1599s (asym) s (sym) 1420m, 1389s (sym) br 3181m m (asym) 1342m (sym) 1101m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.158) in THF showed a broad d-d band at 610 nm (ε max = M -1 cm -1 ) suggesting an octahedral geometry around Co(II) [319, 320], as similarly suggested for [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] nm Figure UV-vis spectrum of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] Its µ eff value, calculated from the values of FM = g mol -1, χ g = 2.0 x 10-5 cm 3 g -1, χ M = 2.9 x 10-2 cm 3 mol -1, and χ dia = -8.8 x 10-4 cm 3 mol -1, was 8.5 B.M. at 298 K. The value was similar to [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ], and may be similarly explained. 200

232 Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.148). [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] reacted with cyclam to form [Co(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ].2H 2 O (15). It was obtained as a purple powder (Scheme 4.2) and the yield was 60.0%. Its chemical formula, based on the results of elemental analyses, is C 44 H 78 NiN 4 O 8 (FW = g mol -1 ; Calc.: C, 63.6; H, 9.6; N, 6.2%. Found: C, 63.5; H, 9.8; N, 6.5%). Its FTIR spectrum (Figure 4.159) showed the presence of all of the expected functional groups (Table 4.23). The Δ value (230 cm -1 ) suggested monodentate 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands [294] T% cm -1 Figure FTIR spectrum of [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.160) in CHCl 3 shows a band at 553 nm (ε max = 72.8 M -1 cm -1 ) similar to 14, and may be similarly assigned. 201

233 abs nm Figure UV-vis spectrum of [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.1 x 10-5 cm 3 g -1, χ M = 1.0 x 10-2 cm 3 mol -1, and χ dia = -5.8 x 10-4 cm 3 mol -1 ; was 5.1 B.M at 298 K, suggesting a mononuclear Co(II) octahedral complex ( B.M.) [319, 322, 323] similar to 14. Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to 14 (Figure 4.151). b) Thermal behavior The TGA trace of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.161) showed an initial weight loss of 1.2% (expected, 1.3%) from 219 o C to about 257 o C due to the evaporation of bridging H 2 O molecule, followed by 90.5% (expected, 90.5%) from 300 o C to about 515 o C due to the evaporation of coordinated H 2 O molecules and decomposition of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, leaving 8.3% residue at temperatures above 515 o C (expected 8.2%, assuming CoO) [292]. The result is in agreement with its chemical formula, and it was thermally as stable (T dec = 300 o C) as [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (T dec = 300 o C). 202

234 Weight (%) Weight (%) Temperature ( C) Figure TGA trace for [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] The TGA trace of 15 (Figure 4.162) showed an initial weight loss of 3.3% (expected, 3.9%) from 54 o C to about 107 o C due to the evaporation of lattice H 2 O molecules, followed by 89.5% (expected, 89.1%) from 229 o C to about 600 o C due to the decomposition of cyclam and 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, leaving 7.2% residue at temperatures above 600 o C (expected, 7.0%, assuming CoO) [292]. The result is in agreement with its chemical formula and its thermal stability (T dec = 229 o C) was similar to 14 (T dec = 229 o C) Temperature ( C) Figure TGA trace for [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 203

235 Heat flow (mw) c) Mesomorphic properties The DSC scans of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.163), recorded in the temperature range o C, showed four endotherms on heating at 46.3 o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds and van der Waals forces, 99.6 o C (ΔH = kj mol -1 ) assigned to the dissociation of H 2 O molecules, o C (ΔH = kj mol -1 ) assigned to its melting temperature, and o C (ΔH = kj mol -1 ) assigned to its clearing temperature. On cooling, there were two exotherms at o C (ΔH = kj mol -1 ) assigned to hydrogen bonds formation and o C (ΔH = kj mol -1 ) assigned to its freezing temperature. Viewed under POM, it was observed to melt at 140 o C and to clear to an isotropic liquid phase at 220 C but no optical textures on cooling from 220 o C. Hence, it was not mesogenic. 2.5 Heating Cooling Temperature ( C) Figure DSC scans of [Co 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 5 ] The DSC for 15 was recorded in the temperature range C. The scans (Figure 4.164) showed three endotherms at 54.0 o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds, o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition on heating. On cooling, there were two exotherms at 87.8 o C (ΔH = -1.2 kj mol -1 ) assigned to the isotropic liquid-to-mesophase 204

236 Heat flow (mw) transition and 54.0 o C (ΔH = kj mol -1 ) assigned to the formation of hydrogen bonds Heating Cooling Temperature ( C) Figure DSC scans of [Co(cyclam)(R) 2 ].2H 2 O (15) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Viwed under POM, it was observed to melt at 118 o C and to clear to an isotropic liquid phase at 140 o C. On cooling from isotropic liquid phase, an optical texture, similar to 14, was observed at 91 o C (Figure 4.165a), which then coalesced on further cooling and became brighter at 65.7 o C (Figure 4.165b). Hence, the complex was mesogenic. (a) (b) Figure Photomicrographs (on cooling) of [Co(cyclam)(R) 2 ].2H 2 O (15) at: (a) 91 o C; and (b) 65.7 o C (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 205

237 4.8.3 [Co(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 )].2H 2 O a) Synthesis and structural elucidation Similar to 14 and 15, [Co(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O (16) was prepared following the procedure shown in Scheme 4.2. [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] was obtained as a purple powder and the yield was 53.3%. Its chemical formula based on the results of the elemental analyses is C 84 H 142 Co 2 O 17 (FW= g mol -1 ; Calc. C, 65.4; H, 9.3%. Found: C, 65.7; H, 9.0%). Its FTIR spectrum (Figure 4.166) showed the presence of all of the expected functional groups (Table 4.24). The Δ values were 210 cm -1 and 142 cm -1, suggesting monodentate [294] and bridging bidentate [79] 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands, respectively T% cm -1 Figure FTIR spectrum of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] 206

238 abs Table 4.24 FTIR data and assignments of [Co 2 (R) 4 (H 2 O) 5 ] and [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Co 2 (R) 4 (H 2 O) 5 ] 3600m s (asym) 1599s, 1561s (asym) s (sym) 1389s, 1419s (sym) br 3183m m (asym) 1364m (sym) 1100m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.167) in THF showed a broad d-d band at 622 nm (ε max = M -1 cm -1 ), suggesting an octahedral geometry at Co(II) [319, 320] as similar suggested for [Co 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (n = 9, 11) nm Figure UV-vis spectrum of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.9 x 10-5 cm 3 g -1, χ M = 3.0 x 10-2 cm 3 mol -1, and χ dia = -9.7 x 10-4 cm 3 mol -1 ) was 8.6 B.M. at 298 K. The value was similar to [Co 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (n = 9, 11), and may be similarly explained. 207

239 Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.148). [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] reacted with cyclam to form [Co(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ].2H 2 O (16). It was obtained as a purple powder (Scheme 4.2) and the yield was 60.0%. Its chemical formula based on the results of elemental analyses is C 52 H 94 CoN 4 O 8 (FW= g mol -1, calc.: C, 64.9; H, 9.9; N, 5.8%. Found: C, 64.9; H, 9.1; N, 5.5%). Its FTIR spectrum (Figure 4.168) showed the presence of all of the expected functional groups (Table 4.24). The Δ value was 235 cm -1, in agreement with monodentate 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands [294] T% cm -1 Figure FTIR spectrum of [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.169) in CHCl 3 showed a band at 535 nm (ε max = M -1 cm -1 ) similar to 14 and 15, and may be similarly assigned. 208

240 abs nm Figure UV-vis spectrum of [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.0 x 10-5 cm 3 g -1, χ M = 9.6 x 10-3 cm 3 mol -1, and χ dia = x 10-4 cm 3 mol -1 was 4.9 B.M at 298 K. This is in agreement with a mononuclear Co(II) octahedral complex ( B.M.) [319, 322, 323] similar to 14 and 15. Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to 14 (Figure 4.151). b) Thermal behavior The TGA trace of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.170) showed an initial weight loss of 1.2% of its mass (expected, 1.2%) from 223 o C to about 255 o C due to the evaporation of bridging H 2 O, followed by 91.1% (expected, 91.2%) from 300 o C to about 511 o C due to the evaporation of coordinated H 2 O molecules and the decomposition of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands, leaving 7.7% residue at temperatures above 511 o C (expected 7.6%, assuming CoO) [292]. The result is in agreement with its chemical formula and it was thermally as stable (T dec = 300 o C) as [Co 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 4 ] (T dec = 300 o C for n = 9 and 11 both). 209

241 Weight (%) Weight (%) Temperature ( C) Figure TGA trace for [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] The TGA trace of 16 (Figure 4.171) shows an initial weight loss of 4.2% of its mass (expected, 3.7%) from 54 o C to about 148 o C due to the evaporation of lattice H 2 O molecules, followed by 86.2% (expected, 90.1%) from 239 o C to about 545 o C due to the decomposition of cyclam and the (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) ligands, leaving 9.6% residue at temperatures above 545 o C (expected, 6.1%, assuming CoO) [292]. The result is in agreement with its chemical formula and its thermal stability (T dec = 239 o C) was similar to 14 and 15 (T dec = 229 o C for both) Temperature ( C) Figure TGA trace for [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 210

242 Heat flow (mw) c) Mesomorphic properties The DSC scans of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.172), recorded in the temperature range o C, showed three endotherms on heating at 47.3 o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds and van der Waals forces, o C (ΔH = kj mol -1 ) assigned to its melting temperature, and o C (ΔH = kj mol -1 ) assigned to its clearing temperature. On cooling no exotherm was appeared. Viwed under POM it was observed to clear at 255 o C and no optical texture was observed on cooling from this temperature. Hence it was non mesogenic Heating Cooling Temperature ( C) Figure DSC scans of [Co 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 5 ] The DSC of 16 was recorded in the temperature range o C. The scans (Figure 4.173) showed three endotherms on heating at o C (ΔH = kj mol -1 ) assigned to the breaking of Van der Waals forces, 75.0 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition. On cooling two exotherms at 58.3 o C (ΔH = -0.8 kj mol -1 ) assigned to isotropic liquid-to-mesophase transition and 33.3 o C (ΔH = kj mol -1 ) assigned to mesophase-to-crystal transition. 211

243 Heat flow (mw) Heating Cooling Temperature ( C) Figure DSC scans of [Co(cyclam)(R) 2 ].2H 2 O (16) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Viwed under POM it was observed to melt at 86 o C and to clear to an isotropic liquid phase at o C. On cooling from isotropic liquid phase an optical texture was observed at 56.7 o C (Figure 4.174a). The sample was crystallized at 45.7 o C (Figure 4.174b). (a) (b) Figure Photomicrographs (on cooling) of [Co(cyclam)(R) 2 ].2H 2 O (16) at: (a) 56.7 o C; and (b) 45.7 o C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 212

244 4.8.4 [Co(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 )].2H 2 O a) Synthesis and structural elucidation Similar to 14 16, [Co(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O (17) was prepared following the procedure as shown in Scheme 4.2. [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O was obtained as a purple powder and the yield was 59.1%. Its chemical formula, based on the results of elemental analyses, is C 92 H 162 Co 2 O 19 (FW = g mol -1 ; Calc. C, 66.8; H, 9.6%. Found: C, 66.9; H, 10.5%). Its FTIR spectrum (Figure 4.175) showed the presence of all of the expected functional groups (Table 4.25). The Δ values were 148 cm -1 and 212 cm -1, suggesting bridging bidentate [79] and monodentate [294] 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, respectively. 97 T% cm -1 Figure FTIR spectrum of [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 213

245 abs Table 4.25 FTIR data and assignments of [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O and [Co(cy)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO, cy = cyclam) Compound Wavenumber*, (cm -1 ) O-H N-H CH 2 COO C-N [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O 3607br s (asym) 1609m, 1591m (asym) s (sym) 1397m, 1443m (sym) br 3187m 2918s (asym) 2852s (sym) 1598m (asym) 1386m (sym) 1101m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum (Figure 4.176) in THF showed a broad d-d band at 604 nm (ε max = M -1 cm -1 ) suggesting an octahedral geometry at Co(II) [319, 320], as similarly suggested for [Co 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (n = 9, 11, and 13) nm Figure UV-vis spectrum of [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.4 x 10-5 cm 3 g -1, χ M = 2.4 x 10-2 cm 3 mol -1, and χ dia = -1.1 x 10-3 cm 3 mol -1, was 7.7 B.M. at 298 K. The value was similar to [Co 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (n = 9, 11, and 13), and may be similarly explained. 214

246 Combining the instrumental data discussed above, the proposed structural formula for the complex was similar to [Co 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 5 ] (Figure 4.148). [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O reacted with cyclam to form [Co(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ].2H 2 O (17). It was obtained as a purple powder (Scheme 4.2) and the yield was 66.0%. Its chemical formula, based on the results of elemental analyses, is C 56 H 102 CoN 4 O 8 (FW = g mol -1 ; Calc.: C, 66.1; H, 10.1; N, 5.5%. Found: C, 66.6; H, 9.9; N, 5.4%). Its FTIR spectrum (Figure 4.177) showed the presence of all of the expected functional groups (Table 4.25). The Δ value was 212 cm -1, in agreement with monodentate 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligands [294] similar to T% cm -1 Figure FTIR spectrum of [Co(cyclam)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.178) in CHCl 3 showed a band at 528 nm (ε max = M -1 cm -1 ), which was similar to 14-16, and may be similarly assigned. 215

247 abs nm Figure UV-vis spectrum of [Co(cyclam)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 1.0 x 10-5 cm 3 g -1, χ M = 1.0 x 10-2 cm 3 mol -1, and χ dia = -6.8 x 10-4 cm 3 mol -1, was 5.1 B.M at 298 K. This is in agreement with a mononuclear Co(II) octahedral complex ( B.M.) [319, 322, 323] similar to Combining the instrumental data discussed above, the proposed structural formula for the complex is similar to 14 (Figure 4.151). b) Thermal behavior The TGA trace of [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O (Figure 4.179) showed an initial weight loss of 2.0% (expected, 2.1%) from 66 o C to about 100 o C due to the evaporation of lattice H 2 O, followed by 87.3% (expected, 90.9%) from 310 o C to about 486 o C due to the evaporation of coordinated H 2 O and decomposition of 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO ligands, leaving 10.7% residue at temperatures above 486 o C (expected 7.0%, assuming CoO) [292]. The result is in agreement with its chemical formula and its thermal stability (T dec = 300 o C) was similar to [Co 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (T dec = 300 o C for n = 9, 11 and 13). 216

248 Weight (%) Weight (%) Temperature ( C) Figure TGA trace for [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O The TGA trace of 17 (Figure 4.180) showed an initial weight loss of 93.1% (expected, 94.2%) from 282 o C to about 519 o C due to the evaporation of lattice H 2 O and decomposition of cyclam and 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO), leaving 6.9% residue at temperatures above 519 o C (expected, 5.8%, assuming CoO) [292]. The result is in agreement with its chemical formula, and it was thermally more stable (T dec = 282 o C) than 14 and 15 (T dec = 229 o C for both) and 16 (T dec = 239 o C) Temperature ( C) Figure TGA trace for [Co(cyclam)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 217

249 Heat flow (mw) c) Mesomorphic properties The DSC of [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O was recorded in the temperature range o C. The scans (Figure 4.181) showed three endotherms on heating at 98.3 o C (ΔH = kj mol -1 ) assigned to the dissociation of water molecules and breaking of van der Waals forces, o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition. On cooling, there were three exothermic peaks at o C (ΔH = -1.6 kj mol -1 ) assigned to isotropic liquid-to-mesophase transition, 86.9 o C (ΔH = kj mol -1 ) assigned to mesophase-to-crystal transition, and 68.4 o C (ΔH = kj mol -1 ) assigned to crystal-to-crystal transition Heating Cooling Temperature ( C) Figure DSC scans of [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O Viwed under POM, it was observed to melt at 99 o C and to clear to an isotropic liquid phase at 153 o C. On cooling from isotropic liquid phase, faint optical textures were observed at o C (Figure 4.182). Hence the complex is mesogenic. 218

250 Heat flow (mw) Figure Photomicrograph (on cooling) of [Co 2 (R) 4 (H 2 O) 5 ].2H 2 O at o C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) The DSC scans of 17 (Figure 4.183), recorded at temperature range o C, showed four endotherms on heating at 91.7 o C (ΔH = kj mol -1 ) assigned to the breaking of van der Waals forces, 113 o C (ΔH = kj mol -1 ) assigned to the dissociation of water molecules, 150 o C (ΔH = kj mol -1 ) assigned to crystal-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to mesophase-to-isotropic liquid phase transition. On cooling a weak exotherm at 175 o C (ΔH = -0.8 kj mol -1 ) assigned to isotropic liquid-to-mesophase transition and a broad exotherm at 75 o C (ΔH = kj mol -1 ) assigned to mesophase-to-crystal transition. 4 3 Heating Cooling Temperature ( C) Figure DSC scans of [Co(cyclam)(R) 2 ].2H 2 O (17) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 219

251 Viwed under POM it was observed to melt at 155 o C and to clear to an isotropic liquid phase at 190 o C. On cooling from isotropic liquid phase, an optical texture was observed at o C (Figure 4.184a), which became brighter at o C on further cooling (Figure 4.184b). Hence the complex is mesogenic. (a) (b) Figure Photomicrographs (on cooling) of [Co(cyclam)(R) 2 ].2H 2 O (17) at: (a) o C; and (b) o C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4.9 Concluding Remarks [Co 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 5 ] (n = 9, 11, 13 and 15) were obtained in good yields (53-59%). These complexes were dinuclear with octahedral geometry at Co(II), have magnetic susceptibilities in the range of B.M., and were thermally stable (T dec = 300 C). [Co 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 5 ].2H 2 O was mesogenic while the other complexes were not. They reacted with cyclam to form covalent mononuclear complexes, [Co(cyclam)(4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2 ].2H 2 O, in good yields (60-72%). The latter complexes have similar magnetic susceptibilities ( B.M.) and thermal stabilities (T dec = C), and were mesogenic. 220

252 4.10 [Mn(cyclam)(4-ROC 6 H 4 COO) 2 ](4-ROC 6 H 4 COO).2H 2 O [Mn(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO).2H 2 O a) Synthesis and structural elucidation [Mn(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO).2H 2 O (18) was prepared following similar procedure shown in Scheme 4.2, replacing CuSO 4.5H 2 O in Step 3 by MnCl 2.4H 2 O. [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O was obtained as a pale green powder and the yield was 61.6%. Its chemical formula, based on the results of elemental analyses, is C 68 H 110 Mn 2 O 17 (FW = g mol -1 ; Calc. C, 62.3; H, 8.5%. Found: C, 62.0; H, 8.0%). Its FTIR spectrum (Figure 4.185) shows the presence of all of the expected functional groups (Table 4.26). The Δ values were 116 cm -1 and 145 cm -1, suggesting chelating and bridging bidentate [79] 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, respectively T% cm -1 Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 221

253 Table 4.26 FTIR data and assignments of [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O and [Mn(cy)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO, cy = cyclam) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O 3611w s (asym) 1564m, 1509m (asym) s (sym) 1419m, 1393m (sym) br 3155m 2920s (asym) 2852s (sym) 1590m, 1509m(asym) 1367s, 1345m (sym) 1248m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum did not show any peaks for d-d electronic transitions, which is typical for Mn(II) high spin complexes [324]. Its µ eff value, calculated from the values of FM = g mol -1, χ g = 4.1 x 10-5 cm 3 g -1, χ M = 5.4 x 10-2 cm 3 mol -1, and χ dia = -7.6 x 10-4 cm 3 mol -1, was 11.4 B.M. at 298 K. This is significantly higher than the expected value of 8.4 B.M. for two magnetically isolated high-spin Mn(II) ions (S = 5/2) [157, 325]. It may be inferred from this that there was a strong ferromagnetic interaction between the Mn(II) centres in this complex, and that each Mn(II) was in an octahedral environment. Combining the instrumental data discussed above, the proposed structural formula for [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O is shown in Figure [246]. OR OH 2 OH 2 RO O Mn O O Mn O OR O O O O OH 2 OH 2 OR Figure Schematic representation of the proposed structure of [Mn 2 (4-ROC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (R = CH 3 (CH 2 ) 9 ); lattice H 2 O are not shown 222

254 Finally, [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O reacted with cyclam to form [Mn(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO).2H 2 O (18). It was obtained as a green powder and the yield was 60.0%. Its chemical formula, based on the results of elemental analyses, is C 61 H 103 MnN 4 O 11 (FW = g mol -1 ; Calc.: C, 65.2; H, 9.2; N, 4.9%. Found: C, 65.0; H, 9.7; N, 4.9%). The data suggests Mn(II) was oxidised to Mn(III) in this reaction. Its FTIR spectrum (Figure 4.187) showed the presence of all of the expected functional groups (Table 4.26). The Δ values were 164 cm -1 and 223 cm -1, suggesting non coordinated [ ] and monodentate [294] 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, respectively. 90 T% cm Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O Its UV-vis spectrum (Figure 4.188) in CHCl 3 showed a sharp band at 434 nm (ε max = M -1 cm -1 ) and a broad band at 1381 nm (ε max = 48.9 M -1 cm -1 ) correspond to the 5 B 1g 5 E g and 5 B 1g 5 A 1 g electronic transitions respectively, suggesting tetragonally distorted octahedral geometry around Mn(III) (valence electronic configuration d 4 ) [326]. 223

255 abs nm Figure UV-vis spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) Its µ eff value, calculated from the values of FM = g mol -1, χ g = 7.1 x 10-6 cm 3 g -1, χ M = 7.9 x 10-3 cm 3 mol -1, and χ dia = -7.1 x 10-4 cm 3 mol -1, was 4.6 B.M at 298 K. This is in agreement with a mononuclear d 4 Mn(III) in distorted octahedral complex ( B.M.) [327]. Combining the instrumental data discussed above, the proposed structural formula for [Mn(cyclam)(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 2 ].(4-CH 3 (CH 2 ) 9 OC 6 H 4 COO).2H 2 O is shown in Figure RO O O N N Mn N N O O OR - O O OR Figure Proposed structure of [Mn(cyclam)(4-ROC 6 H 4 COO) 2 ](4-ROC 6 H 4 COO).2H 2 O (18) (R = CH 3 (CH 2 ) 9 ); lattice H 2 O are not shown 224

256 Weight (%) b) Thermal behavior The TGA trace of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (Figure 4.190) showed an initial weight loss of 1.0% (expected, 1.4%) from 174 o C to about 200 o C due to the decomposition of lattice H 2 O, followed by 90.1% (expected, 90.2%) from 300 o C to about 518 o C due to the evaporation of coordinated H 2 O and decomposition of 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, leaving 8.9% residue at temperatures above 518 o C (expected 8.4%, assuming MnO) [328]. The result is in agreement with its chemical formula, and its decomposition temperature was 300 o C Temperature ( C) Figure TGA trace for [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O The TGA trace for 18 (Figure 4.191) showed an initial weight loss of 2.0% (expected, 3.2%) from 50 o C to about 150 o C due to the evaporation of lattice H 2 O, followed by 93.1% (expected, 91.9%) from 242 o C to about 525 o C due to the decomposition of the cyclam and 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO - ligands, leaving 4.9% residue (expected, 4.9%, assuming MnO) [328]. The result is in agreement with its chemical formula, and the complex was thermally less stable (T dec = 242 o C) than its precursor [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (T dec = 300 o C). 225

257 Weight (%) Temperature ( C) Figure TGA trace for [Mn(cyclam)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) c) Mesomorphic properties The DSC scan of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (Figure 4.192), recorded in the temperature range o C, showed four endothermic peaks on heating at 118 o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds and van der Waals forces, o C (ΔH = kj mol -1 ) assigned to the dissociation of H 2 O molecules, o C (ΔH = kj mol -1 ) assigned to its melting temperature, and o C (ΔH = kj mol -1 ) assigned to its clearing temperature. On cooling, there was an exotherm at o C (ΔH = kj mol -1 ) assigned to the formation of weak bonds. Viewed under POM, it was observed to melt at 160 o C and to clear to an isotropic liquid phase at o C. However, there was no optical texture observed on cooling from this temperature. Hence, the complex was non mesogenic. 226

258 Heat flow (mw) Heat flow (mw) Heating Cooling Temperature ( C) Figure DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O The DSC of 18 was recorded in the temperature range o C. The scans (Figure 4.193) showed three endotherms at 95 o C (ΔH = kj mol - ) assigned to crystal-to-mesophase transition, 104 o C (ΔH = kj mol -1 ) assigned to mesophase-to-mesophase transition, and 113 o C (ΔH = kj mol -1 ) assigned to its mesophase-to-isotropic liquid phase transition. On cooling, there was a weak exotherm at 90.3 o C (ΔH = -0.8 kj mol -1 ) assigned to the isotropic liquid-to-mesophase transition. 8 6 Heating Cooling Temperature ( C) Figure DSC scans of [Mn(cyclam)(R) 2 ]R.2H 2 O (18) (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 227

259 Viwed under POM, it was observed to melt at 92 o C and to clear to the isotropic liquid phase at 115 o C. On cooling from isotropic liquid phase, an optical texture was observed at 88.1 o C (Figure 4.194a), which coalesced on further cooling and became brighter at 71.3 o C (Figure 4.194b). These observations were in accord with the DSC results, and hence the complex was mesogenic. (a) (b) Figure Photomicrographs of [Mn(cyclam)(R) 2 ]R.2H 2 O (18) on cooling at: (a) 88.1 o C; and (b) 71.3 o C (R = 4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) [Mn(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO).2H 2 O a) Synthesis and structural elucidation Similar to 18, [Mn(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO).2H 2 O (19) was prepared following the same procedure as shown in Scheme 4.2. [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O was obtained as a pale green powder and the yield was 56.9%. Its chemical formula, based on the result of elemental analyses, is C 76 H 128 Mn 2 O 18 (FW = g mol -1 ; Calc. C, 64.2; H, 8.9%. Found: C, 64.5; H, 8.8%). 228

260 Its FTIR spectrum (Figure 4.195) showed the presence of all of the expected functional groups (Table 4.27). The Δ values were 114 cm -1 and 148 cm -1, suggesting chelating and bridging bidentate carboxylate ligands [79], respectively T% cm -1 Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 400 Table 4.27 FTIR data and assignments of [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O and [Mn(cy)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO, cy = cyclam) Compound Wavenumber, (cm -1 ) O-H N-H CH 2 COO C-N [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O 3614w s (asym) 1566m, 1507m (asym) s (sym) 1418m, 1393m (sym) br 3104m 2918s (asym) 2853s (sym) 1592m,1544m (asym) 1381s, 1374s (sym) 1241m br, broad; s, strong; m, medium; w, weak. Its UV-vis spectrum did not show any peaks for d-d electronic transitions, similar to [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O, and may be similarly explained. Its µ eff value, calculated from the values of FM = g mol -1, χ g = 3.3 x 10-5 cm 3 g -1, χ M = 4.7 x 10-2 cm 3 mol -1, and χ dia = -8.8 x 10-4 cm 3 mol -1, 229

261 was 10.8 B.M. at 298 K. The value was similar to [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].2H 2 O, and may be similarly explained. Combining the instrumental data discussed above, it is proposed that its structural formula is similar to [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].2H 2 O (Figure 4.186). [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O reacted with cyclam to form [Mn(cyclam)(4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 11 OC 6 H 4 COO).2H 2 O (19). It was obtained as green needles and the yield was 61.5%. Its chemical formula based, on the result of elemental analyses, is C 67 H 115 Mn 2 N 4 O 11 (FW = g mol -1 ; Calc.: C, 66.6; H, 9.6; N, 4.6%. Found: C, 65.0; H, 10.5; N, 5.1%). The complex (Figure 4.196a) crystallized in the triclinic system with the space group P -1. Crystal data and refinement details are given in Table 3 and selected bond lengths and angles are given in Table 5 in the APPENDIX A. Its molecular structure showed that the crystallographic asymmetric unit comprised two half [Mn(cyclam)(CH 3 (CH 2 ) 11 OC 6 H 4 COO) 2 ] 3+ cations, each was disposed about a centre of inversion, and a water molecule of crystallisation (Figure 4.196a). There was one free CH 3 (CH 2 ) 11 OC 6 H 4 COO - anion in the structure. Each Mn(III) atom existed within a trans-n 4 O 2 donor set (Mn1 N1 = 2.027(4) Å, Mn1 N2 = 2.053(4) Å and Mn1 O1 = 2.138(3) Å; Mn2 N3 = 2.057(4) Å, Mn2 N4 = 2.057(4) Å and Mn2 O4 = 2.125(3) Å). Each of the alkyl chains coordinated to Mn(III) adopted an extended, all-trans conformation. The major difference between the alkyl chains was the relative orientations of the carboxylate group with respect to the phenyl ring to which it was attached, being either twisted [O1 C6 C9 C10 torsion angle = 155.5(5)º] or co-planar with [O4 C30 C31 C36 =-173.0(4)º]. The relatively long Mn1 O1 distance compared to Mn1-N1 and Mn1-N2 distances and Mn1 O1 distance compared to Mn2-N3 and Mn2-N4 distances was a consequence of the Jahn-Teller distortion that caused the cationic complex to exhibit axial elongation. 230

262 The components of the crystallographic asymmetric unit were connected via O H O hydrogen bonds whereby lattice water molecule bridged the carboxylate-o atoms (Table 4.28). One amine-n1 H atoms formed N H O hydrogen bond to O10 atom of a lattice water molecule. Each amine N3-H atoms formed N H O hydrogen bonds to two O5 carboxylate-o atom of coordinated alkyloxy chain. The N4 H atom hydrogen bonded to carboxylate-o7 atom of free (CH 3 (CH 2 ) 11 OC 6 H 4 COO) - anion. As the complex cations lied on a centre of inversion, similar hydrogen bonds were formed on the other side of each CuN 4 plane, leading to a supramolecular chain (Figure 4.196b). Table 4.28 Selected Hydrogen bonds for [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Å and ] D-H A d(d-h) d(h A) d(d A) <(DHA) N1-H3C O (5) 2.04(5) 2.816(5) 145(5) O11-H1C O2 0.83(3) 1.95(3) 2.766(7) 167(4) O11-H11C O5 0.83(3) 2.65(4) 2.769(5) 89(3) N3-H3 O (4) 2.255(3) 2.804(5) 121.8(3) N4-H4 O (4) 2.715(3) 2.865(5) 91.3(3) 231

263 (a) (b) Figure (a) Molecular view, showing displacement ellipsoids at 50% probability level; and (b) supramolecular chain of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) most of the alkyl chains and all non-acidic hydrogen atoms have been removed for clarity. O-H O and N-H O hydrogen bonds are shown in blue and green dashed lines respectively. Colour code: Mn, purple; O, red; N, blue; and C, grey 232

264 abs Its FTIR spectrum (Figure 4.197) showed the presence of all of the expected functional groups (Table 4.27). The Δ values were 170 cm -1 and 211 cm -1, suggested ionic [ ] and monodentate [294] 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO ligands, respectively T% cm Figure FTIR spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.198) in CHCl 3 showed a broad band at 1264 nm (ε max = 24.9 M -1 cm -1 ) and a strong band at 430 nm (ε max = M -1 cm -1 ), similar to that observed for 18, and may be similarly assigned nm Figure UV-vis spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 233

265 Weight (%) The µ eff value, calculated from the values of FM = g mol -1, χ g = 7.4 x 10-6 cm 3 g -1, χ M = 8.9 x 10-3 cm 3 mol -1, and χ dia = -7.8 x 10-4 cm 3 mol -1, was 4.8 B.M at 298 K. This is in agreement with a mononuclear d 4 Mn(III) distorted octahedral complex ( B.M.) [327], similar to 18. b) Thermal behavior The TGA trace of [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (Figure 4.199) showed an initial weight loss of 1.0% (expected, 1.3%) from 170 o C to about 190 o C due to evaporation of lattice H 2 O, followed by 88.9% (expected, 91.0%) from 300 o C to about 562 o C due to the evaporation of coordinated H 2 O and decomposition of 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO - ligands, leaving 9.1% residue at temperatures above 562 o C (expected 7.7%, assuming MnO) [328]. Thus the result is in agreement with its structural formula, and its thermal stability (T dec = 300 o C) was similar to [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (T dec = 300 o C) Temperature ( C) Figure TGA trace for [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O The TGA trace of 19 (Figure 4.200) showed an initial weight loss of 4.0% (expected, 2.9%) from 53 o C to about 95 o C due to evaporation of lattice H 2 O, followed by 90.7% (expected, 92.5%) from 246 o C to about 526 o C due to the decomposition of 234

266 Weight (%) cyclam and 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO ligands, leaving 5.3% residue at temperatures above 526 o C (expected, 4.6% assuming MnO) [328]. Thus the result is in agreement with its structural formula, and it was thermally as stable (T dec = 246 o C) as 18 (T dec = 242 o C) Temperature ( C) Figure TGA trace for [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) c) Mesomorphic properties The DSC of [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O was recorded in the temperature range o C. The scans (Figure 4.201) showed four endotherms on heating at 98.8 o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds and van der Waals forces, o C (ΔH = kj mol -1 ) assigned to the dissociation of H 2 O molecules, o C (ΔH = kj mol -1 ) assigned to its melting temperature, and o C (ΔH = kj mol -1 ) assigned to its clearing temperature. However, there were no peaks on cooling. Viewed under POM, it was observed to melt at 160 o C and to clear to an isotropic liquid at 187 o C, but no optical textures on cooling from this temperature. Hence, the complex was non mesogenic. 235

267 Heat flow (mw) Heat flow (mw) 4 3 Heating Cooling Temperature ( C) Figure DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O The DSC scans of 19 (Figure 4.202), recorded in the temperature range o C, showed two endotherms at 67.2 o C (ΔH = kj mol -1 ) assigned to its crystal-to-mesophase transition, and at 82.5 o C (ΔH = kj mol -1 ) assigned to its mesophase-to-isotropic liquid phase transition. However, there were no peaks on cooling. 15 Heating Cooling Temperature ( C) Figure DSC scans of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) Viewed under POM, it was observed to melt at 70 o C and to clear to an isotropic liquid phase at 106 o C. On cooling from isotropic liquid phase, an optical texture was 236

268 observed at 90.1 o C (Figure 4.203a), which then coalesced on further cooling and became brighter at 56.7 o C (Figure 4.203b). Hence the complex was mesogenic. (a) (b) Figure Photomicrographs of [Mn(cyclam)(R) 2 ]R.2H 2 O (19) on cooling at: (a) 90.1 o C; and (b) 56.7 o C (R = 4-CH 3 (CH 2 ) 11 OC 6 H 4 COO) [Mn(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO).2H 2 O a) Synthesis and structural elucidation [Mn(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO).2H 2 O (20) was similarly prepared as for 18 and 19 (Scheme 4.2). [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] was obtained as a green powder and the yield was 55.8%. Its chemical formula, based on the results of elemental analyses, is C 84 H 140 Mn 2 O 16 (FW = g mol -1 ; Calc. C, 66.6; H, 9.3%. Found: C, 66.7; H, 9.5%). Its FTIR spectrum (Figure 4.204) showed the presence of all of the expected functional groups (Table 4.29). The Δ values were 81 cm -1 and 148 cm -1, suggesting chelating and bridging bidentate [79] 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO ligands, respectively. 237

269 T% cm -1 Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] Table 4.29 FTIR data and assignments of [Mn 2 (R) 4 (H 2 O) 4 ] and [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) Compound Wavenumber*, (cm -1 ) O-H N-H CH 2 COO C-N [Mn 2 (R) 4 (H 2 O) 4 ] s (asym) 1516s, 1503w (asym) s (sym) 1368m, 1422s (sym) br 3103m 2917s (asym) 2851s (sym) 1596m, 1544m (asym) 1383s, 1373s (sym) 1241m br, broad; s, strong; m, medium; w, weak. Its UV-visible spectrum did not show any d-d electronic transitions, similar to [Mn 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (n = 9, 11), and may be similarly explained. The µ eff value, calculated from the values of FM = g mol -1, χ g = 1.1 x 10-5 cm 3 g -1, χ M = 1.7 x 10-2 cm 3 mol -1, and χ dia = -9.6 x 10-4 cm 3 mol -1, was 6.4 B.M. at 298 K. This is lower than the expected value of 8.37 B.M for two magnetically isolated high-spin Mn(II) ions (S = 5/2) [157, 325]. It may be inferred that, unlike [Mn 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 4 ] (n = 9, 11), there was an antiferromagnetic interaction between Mn(II) centres in this complex. 238

270 Combining the instrumental data discussed above, it is proposed that its structural formula was similar to [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].2H 2 O (Figure 4.186). In the final step, [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] reacted with cyclam to form [Mn(cyclam)(4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 13 OC 6 H 4 COO).2H 2 O (20). The complex was obtained as green crystals and the yield was 60.0%. Its chemical formula, based on the results of elemental analyses, is C 73 H 127 MnN 4 O 11 (FW = g mol -1 ; Calc.: C, 67.9; H, 9.9; N, 4.3%. Found: C, 67.0; H, 10.2; N, 5.0%). The complex (Figure 4.205a) crystallized in the triclinic system with space group P -1. Crystal data and refinement details are given in Table 3 and selected bond lengths and angles are given in Table 5 in the APPENDIX A. Its molecular structure showed that the crystallographic asymmetric unit was comprised of two half [Mn(cyclam)(CH 3 (CH 2 ) 13 OC 6 H 4 COO) 2 ] 3+ cations, as each was disposed about a centre of inversion (Figure 4.205a). There was a water molecule of crystallisation and one free (CH 3 (CH 2 ) 11 OC 6 H 4 COO) - anion in the crystal structure. Each Mn(III) atom existed within a trans-n 4 O 2 donor set [Mn1 N1 = 2.040(3) Å, Mn1 N2 = 2.045(3) Å and Mn1 O1 = 2.128(2) Å; Mn2 N3 = 2.033(3) Å, Mn2 N4 = 2.047(3) Å and Mn2 O3 = 2.138(2) Å]. The alkyl chains coordinated to Mn(III) adopted an extended, all-trans conformation. The major difference between the alkyl chains was related to the relative orientations of the carboxylate group with respect to the phenyl ring to which it was attached, being either twisted [O3 C5 C6 C7 torsion angle = 151.2(4)º] or co-planar with [O1 C28 C29 C34 =-171.5(3)º]. The relatively long Mn1 O1 distance compared to Mn1-N1 and Mn1-N2 distances and Mn2 O1 distance compared to Mn2-N3 and Mn2-N4 distances were a consequence of the Jahn-Teller distortion that causes the cationic complex to exhibit axial elongation. 239

271 The components of the crystallographic asymmetric unit were connected via N H O and O H O hydrogen bonds. The solvent water molecule bridged one component to free anion through N-H O and O H O hydrogen bonds respectively; whereby the free anion further connected to another component by its carboxylate-o atoms through N H O bonds. The amine-n1 H atoms formed N H O hydrogen bonds to O2 atom of coordinated carboxylate groups. The N2 H atom hydrogen bonded to carboxylate-o6 atom of free (CH 3 (CH 2 ) 13 OC 6 H 4 COO) - anion. The amine N3-H atoms formed N H O hydrogen bonds to two O4 carboxylate-o atom of coordinated carboxylate group. The N4 H atoms hydrogen bonded to O1W of solvent water. There were no hydrogen bonds in the crystal structure. Table 4.30 Selected Hydrogen bonds for [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) [Å and ] D-H...A d(d-h) d(h A) d(d A) <(DHA) N(1)-H(1C)...O(2)#2 0.81(4) 2.07(4) 2.847(4) 161(4) N(2)-H(2D)...O(6) 0.88(5) 2.05(5) 2.893(4) 161(4) O(1W)-H(2WA)...O(5)#4 0.91(6) 1.79(6) 2.688(5) 166(5) N(3)-H(3D)...O(4)#1 0.82(5) 2.28(5) 3.015(4) 150(4) #1 x+1,-y,-z+1 #2 x+2,-y-1,-z+1 #4 x-1,y+1,z 240

272 (a) (b) Figure (a) Molecular view, showing displacement ellipsoids at 50% probability level; and (b) packing diagram of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO). Colour code: same as in Figure

273 abs Its FTIR spectrum (Figure 4.206) showed the presence of all of the expected functional groups (Table 4.29). The Δ values were 171 cm -1 and 213 cm -1, suggesting ionic [ ] and monodentate [294] 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligand, respectively. 95 T% Figure FTIR spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) cm -1 Its UV-vis spectrum (Figure 4.207) in CHCl 3 showed a weak band at 1197 nm (ε max = 11.3 M -1 cm -1 ) and a stronger band at 424 nm (ε max = 35.5 M -1 cm -1 ), similar to 18 and 19, and may be similarly explained nm Figure UV-vis spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 242

274 Weight (%) The µ eff value, calculated from the values of FM = g mol -1, χ g = 6.2 x 10-6 cm 3 g -1, χ M = 7.9 x 10-3 cm 3 mol -1, and χ dia = -8.5 x 10-4 cm 3 mol -1, was 4.6 B.M at 298 K. This is in agreement with a mononuclear d 4 Mn(III) distorted octahedral complex ( B.M.) [327], similar to 18 and 19. b) Thermal behaviour The TGA trace of [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] (Figure 4.208) showed an initial weight loss of 87.0% (expected, 92.6%) from 300 o C to about 590 o C due to the evaporation of coordinated H 2 O and decomposition of 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO - ligands, leaving 13.0% residue at temperatures above 590 o C (expected 7.4%, assuming MnO) [328]. Thus, the result is in agreement with its structural formula, and it was thermally as stable (T dec = 300 o C) as [Mn 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (T dec = 300 o C for both n = 9 and 11) Temperature ( C) Figure TGA trace for [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] The TGA trace of 20 (Figure 4.209) showed an initial weight loss of 2.0% (expected, 2.8%) from 60 o C to about 97 o C due to the evaporation of lattice H 2 O, followed by 92.5% (expected, 92.7%) from 242 o C to about 530 o C due to the decomposition of cyclam and 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO ions, leaving 5.5% residue at 243

275 Weight (%) temperatures above (expected, 4.3% assuming MnO) [328]. Thus the result is in agreement with its structural formula, and it was thermally as stable (T dec = 242 o C) as 18 and 19 (T dec = 242 o C and 246 o C, respectively) Temperature ( C) Figure TGA trace for [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) c) Mesomorphic behaviour The DSC of [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] was recorded in the temperature range o C. The scans (Figure 4.210) showed three endotherms on heating at 92.0 o C (ΔH = kj mol -1 ) assigned to the breaking of hydrogen bonds and van der Waals forces, o C (ΔH = kj mol -1 ) assigned to its melting temperature, and o C(ΔH = kj mol -1 ) assigned to its clearing temperature. On cooling, there was an exotherm at 92.0 o C (ΔH = kj mol -1 ) assigned to the formation of hydrogen bonds and van der Waals forces. Viewed under POM, it was observed to melt at 150 o C and to clear to an isotropic liquid phase at 198 o C. However, there were no optical textures on cooling from this temperature. Hence, the complex was non mesogenic. 244

276 Heat flow (mw) Heat flow (mw) 6 4 Heating Cooling Temperature ( C) Figure DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 4 (H 2 O) 4 ] The DSC scans of 20 (Figure 4.211), recorded in the temperature range o C, showed two endotherms on heating at o C (ΔH = kj mol -1 ) assigned to its crystal-to-mesophase transition, and o C (ΔH = kj mol -1 ) assigned to its mesophase-to-isotropic liquid phase transition. On cooling, there was a weak exotherm at 98.7 o C (ΔH = -1.1 kj mol -1 ) assigned to isotropic liquid-tomesophase transition, and a stronger exotherm at 36 o C (ΔH = kj mol -1 ) assigned to its mesophase-to-crystal transition. 12 Heating Cooling Temperature ( C) Figure DSC scans of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) 245

277 Viewed under POM, it was observed to melt at o C and to clear to an isotropic liquid phase at 118 o C. On cooling from the isotropic liquid phase, an optical texture was observed at 90 o C. The texture captured at 82.9 o C is shown in Figure 4.212a. The sample crystallized at 43.4 o C (Figure 4.212b). Hence the complex was mesogenic. (a) (b) Figure Photomicrographs (on cooling) of [Mn(cyclam)(R) 2 ]R.2H 2 O (20) at: (a) 82.9 o C; and (b) 43.4 o C (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) [Mn(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO).2H 2 O a) Synthesis and structural elucidation Similar to 18-20, [Mn(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO).2H 2 O (21) was prepared following the procedure shown in Scheme 4.2. [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O was obtained as a pale green powder and the yield was 63.9%. Its chemical formula based on the results of elemental analyses is C 92 H 156 Mn 2 O 16 (FW= g mol -1 ; Calc. C, 67.1; H, 9.7%. Found: C, 67.5; H, 9.6%). Its FTIR spectrum (Figure 4.213) showed the presence of all of the expected functional groups (Table 4.31). The Δ values were 127 cm -1 and 151 cm -1 suggesting 246

278 the chelating and bridging bidentate [79] 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligands respectively T% cm -1 Figure FTIR spectrum of [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O 400 Table 4.31 FTIR data and assignments of [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O and [Mn(cy)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO, cy = cyclam) Compound Wavenumber*, (cm -1 ) O-H N-H CH 2 COO C-N [Mn 2 (R) 4 (H 2 O) 4 ].H 2 O 3344br s (asym) 1550m, 1506m (asym) s (sym) 1423m, 1355m (sym) br 3130m 2916s (asym) 2851s (sym) 1593m, 1532m (asym) 1389s, 1374s (sym) 1243m br, broad; s, strong; m, medium; w, weak. Its UV-visible spectrum did not show any d-d electronic transitions, similar to [Mn 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (n = 9, 11 and 13), and may be similarly explained. Its µ eff value calculated from the values of FM = g mol -1, χ g = 2.3 x 10-5 cm 3 g -1, χ M =3.7 x 10-2 cm 3 mol -1, and χ dia = -1.1 x 10-3 cm 3 mol -1, was 9.6 B.M. at 298 K. The value was similar to [Mn 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 4 ] (n = 9 and 11) and may be similarly explained. 247

279 Combining the instrumental data discussed above, it is proposed that its structural formula was similar to [Mn 2 (4-CH 3 (CH 2 ) 9 OC 6 H 4 COO) 4 (H 2 O) 4 ].2H 2 O (Figure 4.186). In the final step, [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O reacted with cyclam to form [Mn(cyclam)(4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) 15 OC 6 H 4 COO).2H 2 O (21). It was obtained as a green powder (Scheme 4.2) and the yield was 68.2%. Its chemical formula based on the result of elemental analyses is C 79 H 139 MnN 4 O 11 (FW= g mol -1 ; Calc.: C, 68.9; H, 10.2; N, 4.1%. Found: C, 69.2; H, 10.3; N, 4.2%). Its FTIR spectrum (Figure 4.214) showed the presence of all of the expected functional groups (Table 4.31). The Δ values were 184 cm -1 and 204 cm -1 suggesting the ionic [ ] and monodentate [294] 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligands, respectively T% cm Figure FTIR spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Its UV-vis spectrum (Figure 4.215) in CHCl 3 showed a sharp band at 429 nm (ε max = M -1 cm -1 ) and a broad band at 1308 nm (ε max = 49.9 M -1 cm -1 ), similar to 18-20, and may be similarly explained. 248

280 abs nm Figure UV-vis spectrum of [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) The µ eff value, calculated from the values of FM = g mol -1, χ g = 5.7 x 10-6 cm 3 g -1, χ M = 7.8 x 10-3 cm 3 mol -1, and χ dia = -9.2 x 10-4 cm 3 mol -1, was 4.6 B.M at 298 K. This is in agreement with a mononuclear d 4 Mn(III) distorted octahedral complex ( B.M.) [327], similar to b) Thermal behavior The TGA trace of [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (Figure 4.216) showed an initial weight loss of 1.0% (expected, 1.1%) from 80 o C to about 107 o C due to the evaporation of lattice H 2 O, followed by 88.1% (expected, 92.2%) from 300 o C to about 554 o C due to the evaporation of coordinated H 2 O, decomposition of cyclam and 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligands, leaving 10.9% residue at temperatures above 554 o C (expected 6.7%, assuming MnO) [328]. Thus the result is in agreement with its structural formula and it was thermally as stable (T dec = 300 o C) as [Mn 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (T dec = 300 o C for n = 9, 11, and 13). 249

281 Weight (%) Weight (%) Temperature ( C) Figure TGA trace for [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O The TGA trace of 21 (Figure 4.217) shows an initial weight loss of 93.6% (expected, 96.0%) from 253 o C to about 542 o C due to the evaporation of H 2 O molecules, dissociation of cyclam and 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO - ligands, leaving 6.4% residue (expected 4.0%, assuming MnO) [328]. Thus the result is in agreement with its structural formula and it was thermally as stable (T dec = 253 o C) as (T dec = 242, 246, and 242 o C, respectively) Temperature ( C) Figure TGA trace for [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 250

282 Heat flow (mw) c) Mesomorphic properties The DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O (Figure 4.218), recorded in temperature range o C, showed a broad endotherm on heating at 100 o C (ΔH = kj mol -1 ) assigned to the dissociation of H 2 O molecules. On cooling no exotherm is appeared. Viewed under POM, However, there were no optical textures observed on cooling. Hence, the complex was non mesogenic Heating Cooling Temperature ( C) Figure DSC scans of [Mn 2 (4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 4 (H 2 O) 4 ].H 2 O The DSC of 21 was recorded in temperature range o C. The scans (Figure 4.219) showed two endotherms on heating at 90.2 o C (ΔH = kj mol -1 ) assigned to its crystal-to-mesophase transition and at o C (ΔH = kj mol -1 ) assigned to its mesophase-to-isotropic liquid phase transition. On cooling there was a weak exotherm at o C (ΔH = kj mol -1 ) assigned to isotropic liquid-tomesophase transition and a stronger exotherm at 48.0 o C (ΔH = kj mol -1 ) assigned to its mesophase-to-crystal transition. 251

283 Heat flow (mw) 9 6 Heating Cooling Temperature ( C) Figure DSC scans of [Mn(cyclam)(R) 2 ]R.2H 2 O (21) (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) Viewed under POM it was observed to melt at 90 o C and to clear to an isotropic liquid phase at 117 o C. On cooling from isotropic liquid phase an optical texture was observed at 90.8 o C (Figure 4.220a) which was coalesced on further cooling and became brighter at 88.9 o C (Figure 4.220b). The sample was crystallized at around 38.7 o C (Figure 4.220c). Hence, the observations were in accord with DSC results and the complex was mesogenic. (a) (b) (c) Figure Photomicrographs (on cooling) of [Mn(cyclam)(R) 2 ]R.2H 2 O (21) at: (a) 90.8 o C; (b) 88.9 o C; and (c) 38.7 o C (R = 4-CH 3 (CH 2 ) 15 OC 6 H 4 COO) 252

284 4.11 Concluding Remarks [Mn 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 4 ] (n = 9, 11, 13 and 15) were obtained in good yields (55-63%). These complexes were dinuclear with octahedral geometry at Mn(II), have magnetic susceptibilities in the range of B.M., and were thermally stable (T dec = 300 C for all). They reacted with cyclam to form covalent mononuclear complexes, [Mn(cyclam)(4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2 ](4-CH 3 (CH 2 ) n OC 6 H 4 COO).2H 2 O, in good yields (60-68%). The latter complexes have similar magnetic susceptibilities ( B.M.) and thermal stabilities (T dec = C), and were mesogenic. 253

285 CHAPTER 5. CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORKS 5.1 Conclusions Dinuclear Cu(II), Ni(II), Co(II) and Mn(II) complexes of 4-alkyloxybenzoates were successfully synthesized and characterized. These complexes reacted with cyclam to form the corresponding mononuclear metal(ii)-cyclam arylcarboxylates in good yields (56-72%). The chemical formulae of these complexes are shown in Table 5.1. Table 5.1 Chemical formulae of studied complexes Metal(II) arylcarboxylate precursors Metal(II)-cyclam arylcarboxylates [Cu 2 (4-XC 6 H 4 COO) 4 (CH 3 CH 2 OH) 2 ] [Cu(cyclam)(L) 2 ](4-XC 6 H 4 COO) 2.2H 2 O [Cu 2 (3,5-(NO 2 ) 2 C 6 H 3 COO) 4 (CH 3 CH 2 OH) 2 ] [Cu(cyclam)(L) 2 ](3,5-(NO 2 ) 2 C 6 H 3 COO) 2 [Cu 2 (R) 4 (H 2 O) 2 ] [Cu(cyclam)(H 2 O) 2 ](R) 2.2H 2 O [Ni 2 (R) 4 (H 2 O) 5 ] [Ni(cyclam)(R) 2 ].2H 2 O [Co 2 (R) 4 (H 2 O) 5 ] [Co(cyclam)(R) 2 ].2H 2 O [Mn 2 (R) 4 (H 2 O) 4 ] [Mn(cyclam)(R) 2 ]R.2H 2 O X = F, Cl, Br, I, and NO 2 ; R = 4-CH 3 (CH 2 ) n OC 6 H 4 COO (n = 9, 11, 13, 15) All Cu(II) arylcarboxylate precursor complexes were paramagnetic, and all [Cu 2 (4-CH 3 (CH 2 ) n OC 6 H 4 COO) 4 (H 2 O) 2 ] (n = 9, 11, 13, 15) were mesogenic. Ni(II) arylcarboxylate precursor complexes with n = 9 and 11, were ferromagnetic, while complexes with n = 13 and 15, were paramagnetic. All complexes, except for complex with n = 13, were nonmesogenic. All Co(II) arylcarboxylate precursor complexes were ferromagnetic, and except for complex with n = 15, were nonmesogenic. All Mn(II) arylcarboxylate precursor complexes were ferromagnetic while [Mn 2 (R) 4 (H 2 O) 4 ] (R = 4-CH 3 (CH 2 ) 13 OC 6 H 4 COO) was antiferromagnetic. These complexes were also nonmesogenic. Finally, all metal(ii)-cyclam arylcarboxylates were paramagnetic mesogens. 254

286 5.2 Suggestions for Future Works The mesogenic properties exhibited by complexes reported in this work were inferred from DSC and POM data. It is suggested that the type of mesophases are confirmed by variable temperature small angle X-ray scattering (SAXS) experiments. In addition, molecular modelling based on the density functional theory (DFT) may be used to study their structure-properties correlations, especially magnetic and electronic properties. These complexes are also thermotropic liquid crystals. The complexes reported in this work have even numbers of carbon atoms in the alkyoxy chain, namely [M(cyclam)](4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2 (n = 9, 11, 13, 15). Hence, it is of interest to study the effect of odd numbers of carbon atoms in these chains in order to compare the type and stability of mesophases as well as other properties. Mesogens with odd numbers of carbon atoms are expected to have lower melting and clearing temperatures, which will minimise their thermal decompositions. Also, since the complexes, [Cu(cyclam)](4-CH 3 (CH 2 ) n OC 6 H 4 COO) 2 are ionic, they are potential thermoelectric materials for converting waste heat directly to electricity [ ], and as functional ionic liquids [128]. Metallomesogens exhibiting spin crossover properties (SCO) are expected to show novel properties originating from interaction between magnetic and liquid crystal properties toward external stimuli, such as temperature, pressure and light. These materials have many advantages in practical applications, such as facile formation of thin films, enhancement of spin transition signals, switching and sensing in different temperature regimes, and/or attainment of photo- and thermochromism [332]. Hence, the SCO properties of the metallomesogens reported in this work may be further studied by Superconducting Quantum Interfering Device (SQUID), which measure molar magnetic susceptibility as a function of temperature, to give important data for device applications, such as SCO temperature (T ½ ) and thermal hysteresis ( T). For instance 255

287 Hayami et al. [23] reported Co(II) complexes exhibiting a unique spin transition induced by phase transitions, and Mn(III)-tetraphenylporphyrin complexes, (Mn[R 4 TPP][TCNE]) [24-26] exhibiting ferromagnetic behaviour with liquid crystalline properties. Also, these complexes are potential photoluminescence materials, and accordingly, research may be expanded to their applications in optoelectronic devices, such as light emitting devices [333], field effect transistors [334], highly emissive gels [335], solar cells [28], and sensors [336]. Venkatesan et al. (2008) [337] reported a series of mononuclear ortho-platinated discotic metallomesogens containing heteroaromatic and 1, 3-diketonate which displayed photoluminescence and hence were of interest for electrooptical applications. Figure 5.1 (a) A platinated discotic metallomesogen, and (b) its optical texture at 120 C (Col h phase) [337] Finally, another application, often cited for metallomesogens is as redox-active catalysts [338] in their mesophase. 256

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324 APPENDIX A Table 1 Crystal data and structure refinement details of Cu(II) - cycalm complexes Empirical formula C24H38CuF2N4O7 C24H36CuN6O10 C24H30CuN8O12 C44H78CuN4O8 (6) C48H88CuN4O9 (7) C56H104CuN4O9 (9) Formula weight Temperature (K) 293(2) 293(2) 298(2) 293(2) 173(2) 293(2) λ (Å) Crystal system Triclinic Triclinic Triclinic Triclinic Triclinic Monoclinic Space group P -1 P -1 P 21/c P -1 P -1 P -1 a (Å) (4) 7.155(3) (9) (8) (4) (18) b (Å) (7) 9.147(4) (8) (10) (6) (3) c (Å) (8) (4) (10) (18) (8) (4) ( ) (5) (6) (2) (3) 89.53(3) ( ) (5) (6) (13) (2) (4) 88.27(3) ( ) (5) (6) (2) (4) 82.15(3) V (Å 3 ) (13) 732.8(5) 1507(2) (2) (18) (10) Z Dcalc (g/cm 3 ) Absorption coefficient (mm -1 ) F(000) Theta range ( ) 2.90 to to to to to to Index ranges -7 h 8-8 h 8, -13 h 13-8 h 8-10 h h k k k k k k l l l l l l 26 Reflections collected Independent reflections (Rint) 4799 (0.0497) 2569 ( ) 2649 ( ) 4141(0.0222) 8806(0.0582) 10147(0.0536) Data / restraints / parameters 4799 / 0 / / 0 / / 0 / / 0 / / 0 / / 0 / 642 Goodness-of-fit on F Final R indices R1 = R1 = R1 = R1 = R1 = R1 = [I>2.0σ(I)] wr2 = wr2 = wr2 = wr2 = wr2 = wr2 = R indices (all data) R1 = R1 = R1 = R1 = R1 = R1 = wr2 = wr2 = wr2 = wr2 = wr2 = wr2 = ρmax, ρmin (e Ǻ -3 ) 0.960, , , , , ,

325 APPENDIX A Table 2 Crystal data and structure refinement details of Ni(II) - cycalm complexes Empirical formula C 44 H 78 N 4 NiO 8 (10) C 48 H 84 N 4 NiO 8 (11) Formula weight Temperature (K) 100(2) 293(2) λ (Å) Crystal system Monoclinic Triclinic Space group P 2 1 /c P 2 1 /c a (Å) (18) (18) b (Å) (9) (9) c (Å) (18) (17) ( ) ( ) (11) (9) ( ) V (Å 3 ) (4) (4) Z 2 2 D calc (g/cm 3 ) Absorption coefficient (mm -1 ) F(000) Theta range ( ) 2.83 to to Index ranges -19 h h k 9-11 k 8-17 l l 14 Reflections collected Independent reflections (R int ) 3969(0.0729) 4308 (0.0722) Data / restraints / parameters 3969 / 0 / / 0 / 282 Goodness-of-fit on F Final R indices R1 = R1 = , [I>2.0σ(I)] wr2 = wr2 = R indices (all data) R1 = R1 = wr2 = wr2 = ρ max, ρ min (e Ǻ -3 ) 0.817, ,

326 APPENDIX A Table 3 Crystal data and structure refinement details of Mn(III) - cycalm complexes Empirical formula C 134 H 230 Mn 2 N 8 O 22 (19) C 146 H 252 Mn 2 N 8 O 20 (20) Formula weight Temperature (K) 296(2) 296(2) λ (Å) Crystal system Triclinic Triclinic Space group P -1 P -1 a (Å) a = (7) a = (2) b (Å) b = (7) b = (3) c (Å) c = (15) c = (6) ( ) = (5) = (10) ( ) = (5) = (10) ( ) = (5) = (10) V (Å 3 ) (4) (14) Z 1 1 D calc (g/cm 3 ) Absorption coefficient (mm -1 ) F(000) Theta range ( ) to to Index ranges -13 h h k k l l 32 Reflections collected Independent reflections (R int ) (0.1227) (0.0347) Data / restraints / parameters / 6 / / 0 / 815 Goodness-of-fit on F Final R indices R1 = R1 = [I>2.0σ(I)] wr2 = wr2 = R indices (all data) R1 = R1 = wr2 = wr2 = ρ max, ρ min (e Ǻ -3 ) 1.173, ,

327 APPENDIX A Table 4 Selected bond lengths (Å) and bond angles ( ) of Cu(II)-cyclam and Ni(II)-cyclam complexes C 24H 38CuF 2N 4O 7 C 24H 36CuN 6O 10 C 24H 30CuN 8O 12 C 44H 78CuN 4O 8 (6) Bond length Bond length Bond length Bond length Cu(1)-N(2) (18) Cu(1)-N(2) (18) Cu(1)-N(2) 1.992(6) Cu(1)-N(2) (15) Cu(1)-N(1) (18) Cu(1)-N(1) (18) Cu(1)-N(1) 1.993(6) Cu(1)-N(1) (15) Cu(1)-O(1W) 2.529(2) Cu(1)-O(1W) 2.529(2) Cu(1)-O(1) 2.465(4) Cu(1)-O(1W) 2.595(1) Bond angle Bond angle Bond angle Bond angle N(2)-Cu(1)-N(2) (1) N(2)-Cu(1)-N(2) (1) N(2)-Cu(1)-N(2) 180.0(3) N(2)-Cu(1)-N(2) 180 N(2)-Cu(1)-N(1) 94.29(7) N(2)-Cu(1)-N(1) 94.29(7) N(2)-Cu(1)-N(1) 86.7(3) N(2)-Cu(1)-N(1) 85.98(6) N(2)-Cu(1)-N(1) 85.71(7) N(2)-Cu(1)-N(1) 85.71(7) N(2)-Cu(1)-N(1) 93.3(3) N(2)-Cu(1)-N(1) 94.02(6) N(1)-Cu(1)-N(1) (10) N(1)-Cu(1)-N(1) (10) N(1)-Cu(1)-N(1) 180.0(3) N(1)-Cu(1)-N(1) (1) C 48H 88CuN 4O 9 (7) C 56H 104CuN 4O 9 (9) C 44H 78N 4NiO 8 (10) C 48H 84N 4NiO 8 (11) Bond length Bond length Bond length Bond length Cu(1)-N(1) 2.018(2) Cu(1)-N(2) 2.018(2) Ni(1)-N(2) 2.062(3) Ni(1)-N(2) 2.076(4) Cu(1)-N(2) 2.026(2) Cu(1)-N(1) 2.036(2) Ni(1)-N(1) 2.071(3) Ni(1)-N(1) 2.078(4) Cu(2)-N(4) 2.013(2) Cu(2)-N(3) 2.014(2) Ni(1)-O(1) 2.096(2) Ni(1)-O(1) 2.094(3) Cu(2)-N(3) 2.017(3) Cu(2)-N(4) 2.017(2) Bond angle Bond angle Bond angle Bond angle N(1)-Cu(1)-N(1) (15) N(2)-Cu(1)-N(2) (14) N(2)-Ni(1)-N(2) (15) N(2)-Ni(1)-N(2) (18) N(1)-Cu(1)-N(2) 85.99(10) N(2)-Cu(1)-N(1) 85.81(10) N(2)-Ni(1)-N(1) 86.13(11) N(2)-Ni(1)-N(1) 86.13(16) N(1)-Cu(1)-N(2) 94.01(10) N(2)-Cu(1)-N(1) 94.19(10) N(2)-Ni(1)-N(1) 93.87(11) N(2)-Ni(1)-N(1) 93.87(16) N(2)-Cu(1)-N(2) 180 N(1)-Cu(1)-N(1) (1) N(1)-Ni(1)-N(1) (16) N(1)-Ni(1)-N(1) (1) N(4)-Cu(2)-N(4) (14) N(3)-Cu(2)-N(3) (13) N(2)-Ni(1)-O(1) 92.80(11) N(2)-Ni(1)-O(1) 89.69(15) N(4)-Cu(2)-N(3) 86.30(10) N(3)-Cu(2)-N(4) 86.29(10) N(2)-Ni(1)-O(1) 87.20(11) N(2)-Ni(1)-O(1) 90.31(15) N(4)-Cu(2)-N(3) 93.70(10) N(3)-Cu(2)-N(4) 93.71(10) N(1)-Ni(1)-O(1) 90.18(11) N(1)-Ni(1)-O(1) 87.23(15) N(3)-Cu(2)-N(3) (10) N(4)-Cu(2)-N(4) (12) N(1)-Ni(1)-O(1) 89.82(11) N(1)-Ni(1)-O(1) 92.77(15) N(1)-Ni(1)-O(1) 90.18(11) O(1)-Ni(1)-O(1) (1) O(1)-Ni(1)-O(1) (16) C(6)-O(1)-Ni(1) 135.1(3) C(2)-N(1)-Ni(1) 117.0(3) C(3)-N(1)-Ni(1) 104.7(3)

328 APPENDIX A Table 5 Selected bond lengths (A) and bond angles ( ) of Mn(II)- cyclam complexes Bond length C 134 H 230 Mn 2 N 8 O 22 (19) C 146 H 252 Mn 2 N 8 O 20 (20) Bond length N(1)-Mn(1) 2.027(4) Mn(1)-N(1) 2.040(3) N(2)-Mn(1) 2.053(4) Mn(1)-N(2) 2.045(3) N(3)-Mn(2) 2.057(4) Mn(1)-O(1) 2.128(2) N(4)-Mn(2) 2.057(4) Mn(2)-N(3) 2.033(3) O(1)-Mn(1) 2.138(3) Mn(2)-N(4) 2.047(3) O(4)-Mn(2) 2.125(3 Mn(2)-O(3) 2.138(2) Bond angle Bond angle N(1)-Mn(1)-N(1) 180 C(28)-O(1)-Mn(1) 134.1(2) N(1)-Mn(1)-N(2) 93.41(15) C(5)-O(3)-Mn(2) 130.6(2) N(1)-Mn(1)-N(2) 86.59(15) N(1)-Mn(1)-N(1) 180 N(1)-Mn(1)-N(2) 93.41(15) N(1)-Mn(1)-N(2) 94.27(11) N(2)-Mn(1)-N(2) 180 N(1)-Mn(1)-N(2) 85.73(11) N(1)-Mn(1)-O(1) 94.29(15) N(2)-Mn(1)-N(2) (2) N(1)-Mn(1)-O(1) 85.71(15) N(1)-Mn(1)-O(1) 92.32(10) N(2)-Mn(1)-O(1) 92.19(15) N(1)-Mn(1)-O(1) 87.68(10) N(2)-Mn(1)-O(1) 87.81(15) N(2)-Mn(1)-O(1) 89.70(10) O(1)-Mn(1)-O(1) 180.0(2) N(2)-Mn(1)-O(1) 90.30(10) N(4)-Mn(2)-N(4) 180 O(1)-Mn(1)-O(1) 180 N(4)-Mn(2)-N(3) 85.63(14) N(3)-Mn(2)-N(3) 180 N(4)-Mn(2)-N(3) 94.37(14) N(3)-Mn(2)-N(4) 93.69(12) N(4)-Mn(2)-N(3) 94.37(14) N(3)-Mn(2)-N(4) 86.31(12) N(3)-Mn(2)-N(3) 180 N(4)-Mn(2)-N(4) 180 N(4)-Mn(2)-O(4) 89.76(14) N(3)-Mn(2)-O(3) 92.10(11) N(4)-Mn(2)-O(4) 90.24(14) N(3)-Mn(2)-O(3) 87.90(11) N(3)-Mn(2)-O(4) 87.77(14) N(4)-Mn(2)-O(3) 93.39(11) N(3)-Mn(2)-O(4) 92.23(14) N(4)-Mn(2)-O(3) 86.61(11) O(4)-Mn(2)-O(4) (16) O(3)-Mn(2)-O(3) (4)

329 APPENDIX B PUBLICATIONS CERTIFICATES OF PARTICIPATIONS IN: NATIONAL AND INTERNATIONAL SEMINARS CONFERENCES

330 APPENDIX B

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335 APPENDIX B