Synthesis and Studies of Mixed ligand Ni(II) and Cu(II) Metal Complexes with 2-Aminophenol and Schiff base of Terephthalaldehyde

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1 Synthesis and Studies of Mixed ligand i(ii) and Cu(II) Metal Complexes with 2-Aminophenol and Schiff base of Terephthalaldehyde Laxman V. Gavali* Post Graduate Department of Chemistry, Karmaveer Bhaurao Patil College Vashi, Sector -5A, avi Mumbai Maharashtra( India) And Mahadeo. R. Jadhav, Department of Applied Science, Bharti Vidyapeeth College of Engineering, avi Mumbai. ABSTRACT Synthesis, structure, and physico-chemical investigation of i (II) and Cu (II) complexes derived from Schiff base of 2- aminophenol with terephthaldehyde and then it allowed to react with metal salts with 8-hydroxyquinoline to form binuclear Schiff base mixed ligand metal complexes. All the synthesized ligand and complexes were characterized based on elemental analysis, H MR,UV-Visible, molar conductance, FTIR, and thermal analysis (TGA/DTA). Molar conductance of the metal complexes shows that chelates are non electrolytic nature. An IR spectrum shows that the Schiff basses are coordinated with donar sites of azomethine nitrogen and phenolic oxygen and qunoline nitrogen and phenolic oxygen of 8-hydroxyquinoline group. Formation of Schiff base ligand was confirmed by H MR spectra. The electronic spectra show that i (II) and Cu (II) complexes have tetrahedral geometry. Thermal stability of complexes was also studied to assess the compatibility of the donating moieties. Schiff base and their metal complexes were studied for antimicrobial activities. Keywords: Schiff Base, 8-hydroxyquinoline, binuclear Mixed ligand metal complex. Introduction Many biologically important Schiff bases have been reported in the literature possessing antimicrobial, antibacterial, antifungal, anti-inflammatory, anticonvulsant, anti-tumor and anti HIV activities []. Schiff base ligands may contain a variety of substituents with different electron-donating or electron-withdrawing groups and therefore may have interesting chemical properties. They have attracted particular interest due to their biological activities e.g. acting as radiopharmaceuticals for cancer targeting [2-3]. Schiff bases are generally bidentate, tridentate, tetradentate or polydentate ligands capable of forming very stable complexes with transition metals. They can only act as coordinating ligands if they bear a functional group, usually the hydroxyl, sufficiently near the site of condensation in such a way that a five or six membered ring can be formed when reacting with a metal ion. Schiff bases derived from aromatic amines and aromatic aldehydes have a wide variety of applications in many fields, e.g. biological, inorganic and analytical chemistry [4]. Applications of many new analytical devices require the presence of organic reagents as essential compounds of the measuring system. Transition metal complexes with Schiff bases have expanded enormously and embraced wide and diversified subjects comprising vast areas of organometallic compounds and various aspects of bio-coordination chemistry [5]. Schiff bases are used in optical and electrochemical sensors, as well as in various chromatographic methods to enable detection of enhanced selectivity and sensitivity [6].Transition metals are known to form Schiff base complexes and Schiff bases have often been used as chelating ligands in the field of coordination chemistry. Their metal complexes have been of great interest for many years. It is well known that, and S atoms play a key role in the coordination of metals at the active sites of numerous metallic biomolecules [7]. Schiff base metal complexes have been widely studied because they have industrial, antifungal, antibacterial, anticancer, antiviral and herbicidal applications [8].They serve as models for biologically important species 72 L. V. Gavali and M. R. Jadhav

2 and find applications in biomimetic catalytic reactions. It is known that the existence of metal ions bonded to biologically active compounds may enhance their activities. The transition elements are V, Cr, Mn, Fe, Co, i, Cu and Zn. These elements are present at trace and ultra-trace quantities and play vital roles at the molecular level in a living system. These transition elements are known to form Schiff base complexes. Schiff base metal complexes have been known since the mid nineteenth century [9] and even before the general preparation of the Schiff base ligands themselves. Schiff base metal complexes have occupied a central place in the development of coordination chemistry after the work of Jorgensen and Werner [0]. Ettlings isolated a dark green crystalline product from the reaction of cupric acetate, salicylaldehyde and aqueous ammonia. Schiff prepared complexes of metal-salicylaldehyde with primary amines []. The study of binuclear and polynuclear complexes of transition metal ions has received a growing attention in recent years. It has been an interesting area for chemists, physicists and biologists, since these complexes form the basis of several research fields such as bioinorganic chemistry, magneto chemistry, material science, catalysis, super conductivity and multi electron redox chemistry etc.,[2-3).the transition metal complexes having oxygen and nitrogen donor Schiff bases possess unusual configurations and structural labiality and are sensitive to the molecular environment. 2-hydroxy Schiff base ligands and their complexes derived from the reaction of derivatives of salicylaldehyde with amines have been extensively studied in great details for their various crystallographic, structural and magnetic features [4-6]. In this paper we report synthesis, characterization and spectroscopic properties of terephthalaldehyde and 2- aminophenol Schiff base and its i(ii) and Cu(II) metal co-ordination complexes. The metal ion in an octahedral environment. The primary aim of the current study to determine the structure and geometry of binuclear Schiff base mixed ligand i(ii) and Cu(II) metal complexes. MATRIALS AD METHDS All the chemicals used were of analytical reagent grade and higher purity (Sigma-Aldrich, Merck) Solvents ethanol, methanol DMF was purified and used according to standard procedure. PHYSICAL MEASUREMETS Elemental analysis (C, H and ) was obtained using Thermo Finnegan, FLASH EA 2 series analyzer from IIT Bombay. The molar conductance of the complex in DMF (0-3 ) solution was measure at 27 0 Cwith Elico model conductivity meter. IR spectra were recorded in Bruker, 3000 Hyperion Microscope with Vertex 80 FTIR System from IIT Bombay. The electronic spectra of the complexes was recorded on Elico double beam UV-Vis Spectrophotometer in the range nm in DMF (0-3 ) solution. Magnetic susceptibility measurement was carried out by Gouy balance method at room temperature. MR signals obtained VARIA, Mercury Plus 300MHz MR Spectrometer from IIT Bombay. Thermal analysis (TG/DTA) were carried out in the range C using Perkin Elmer Diamond TG/DTA thermal analyzer from IIT Bombay. Synthesis of Schiff base ligand L Schiff base ligand was synthesized by adding terephthaladehyde (.34g, 0.0mol) in 20 ml ethanol and 2- aminophenol (2.8g, 0.02 mol) in 20 ml ethanol slowly with constant stirring then mixtures was refluxed for ~6 hrs. The solution was kept for slow evaporation and then precipitate was collected. The precipitate formed was filtered, dried and recrystallized from hot methanol to get pure ligand and checked by TLC. 73 L. V. Gavali and M. R. Jadhav

3 H H 2, 2 -[,4-phenylenebis(methanylidene)]diphenol Synthesis of Binuclear Schiff base i(ii)metal complex The synthesized ligand (3.6g, 0.0mol) was dissolved in 20 ml DMF and added drop wise in the hot ethanolic solution of metal chloride (4.75g, 0.02 mol)with constant stirring, followed by the addition of 8- hydroxyquinoline (2.90g, 0.02mol) in 20 ml ethanol and the mixture was refluxed for 4hrs. Precipitated complex on cooling to room temperature was filtered, washed with ethanol and finally dried over fused CaCl 2 in vacuum yield (82%). Synthesis of Binuclear Schiff base Cu (II) metal complex The synthesized ligand (3.6g, 0.0mol) was dissolved in 20 ml DMF and added drop wise in the hot ethanolic solution of metal chloride (3.42g, 0.02 mol) with constant stirring, followed by the addition of 8- hydroxyquinoline (2.90g, 0.02mol) in 20 ml ethanol and the mixture was refluxed for 4hrs. Precipitated complex on cooling to room temperature was filtered, washed with ethanol and finally dried over fused CaCl2 in vacuum yield (75%) i i nh 2 74 L. V. Gavali and M. R. Jadhav

4 RESULT AD DISCUSSI Table : Analytical data of Schiff base ligand and its binuclear metal complexes Compound /Molecular formula H 2L C 20H (il X 2)n-H 2 C 38H i 2 C 38H Cu 2 Color/ Mol.Wt. Yellow 36 Gray (79) Dark green (765) Yield % M.P C (75.95) 70 < (57.64) 75 < (59.60) Elemental Analysis (cal.) in % C H M 4.96 (5.06) 4.5 (4.29) 9.84 (9.92) 9.00 (8.86) (7.07) 7.28 (7.32) 4.75 (4.83) 6.52 (6.60) IR Spectra The important infra red frequencies of Schiff base and its complexes tabulated in table no.2.the extent of shift depends on the bond strength between the atoms. The synthesized binuclear Schiff base complex the high intense band due to the phenolic H appeared in the region 3365cm - in the Schiff base and was disappeared in the complexes. The band at 502cm - and 448cm - are due to CH deformation mode of vibration of CH bond. The band observed in the region 286cm - for υ(c-) stretching vibration undergoes shift to yield higher wave number of 323cm - and 322cm - compare with free ligand band. These observation support the formation of M- bond via deformation. The H- bonded H group have been replaced by the metal ion. The strong band at 620cm - due to υ(c=) stretching vibration while has been shifted towards lower region at 60cm - and 600cm - in the complexes indicating the participating of the azomethine group in the complex formation this shift due to the reduction of double bond character carbon nitrogen bond of azomethine group and indicates that C= of the ligand co-ordinate to metal through nitrogen and is further reflected by the appearance of new band at cm - due to υ(m=). Several medium intensity band was appeared in the cm - region of the spectra due to starching of C=C vibration aromatic ring. The complex formation was further evidence by the appearance of non-ligand band in the complexes cm - assigned as υ(m-) bonds. The broad band observed in the region between cm - due to asymmetric and symmetric H stretching modes and strong band around 574cm - and 572 cm - due to H-H bonding vibration are indication of the presence of lattice water. The important feature of infrared spectra of the metal complexes is the absence of the band at ~3440cm - due to H stretching vibration of H group of 8-hydroxyqunoline. The deformation of the hydroxyl group of new ligand indicates formation of complex. In the spectra of free 8- hydroxyl quinolone ligand the υ(c-) bond is observed at 69cm - and 67cm -. It is reported that the mixed ligand complexes of i(ii) and Cu(II) with 8-Hydroxyqunoline this band observed at 69cm - and 67cm -. In the present study a strong υ(c-) band is observed at 2cm - inthe spectra of both complexes. Indirectly the presence of 8-hydroxyqunoline found to be shifted to lower wave number 502cm - and 499cm - in the spectra of the metal complexes suggesting co-ordination through tertiary nitrogen donor of 8- hydroxyqunoline. The plane and anti-plane ring deformation mode observed at 56cm - and 73cm - respectively. In the spectra of 8-hydroxy quinoline are shifted to higher wave number 52cm - and 745cm - respectively confirming co-ordination through the nitrogen atom of 8- hydroxyl qunoline with metal ions. 75 L. V. Gavali and M. R. Jadhav

5 Table2: Infrared spectroscopic data of the Schiff base ligand and its metal complexes Compound H 2L C 20H (il X 2)n-H 2 C 38H i 2 C 38H Cu 2 C- cm - C= cm - M- cm - M- cm , , ,582 48,47 H MR spectra H MR spectra of Schiff base was recorded in DMS d 6 at room temperature. The signals at δ 9.03ppm due to intermolecular bonding of phenolic H group. The two proton signals at H-7,δ 8.79 ppm are due to methine protons, H-9/0, δ 8.6 ppm aryl proton, other aryl protons are observed in the range δ ppm as doublet, triplet and multiplet. Table 3: H MR spectral data of Schiff base ligand and its metal complexes Compound H (δ) Methine(δ) Aryl(δ) H 2L C 20H (il X 2)n-H 2 C 38H i 2 C 38H Cu Magnetic Moments and Electronic Spectral Data of the Metal Complexes Magnetic susceptibility measurements carried out by Gouy balance method at room temperature indicated that the nature of i and Cu complex is paramagnetic. i (II) complex showed magnetic moment 2.9 B.M., slightly higher than the spin only(2.83 B.M.), Suggesting that Tetrahedral geometry. Magnetic moments for Cu(II) complex is.80 B.M. indicating distorted Tetrahedral geometry. Electronic spectra: UV visible spectra of mixed ligand metal complexes The electronic spectra of the Schiff base ligand and its i(ii) and Cu(II) mixed ligand metal complexes have been measured 0-3 M solutions in DMF solvent between in range nm at room temperature. In the spectra of Schiff base ligand, the absorption band at 295nm due to intra-ligand π π*and band at 370nm due to the n π* transition indicating azomethine chromophore (C=)i(II) complex shows two transitions bands at 575nm and 665nm indicate that 3 A 2g -- 3 T g(p) and 3 A 2g -- 3 T 2g electronic transitions.the two transitions are indicates that tetrahedral geometry of complex. 76 L. V. Gavali and M. R. Jadhav

6 Table 4:UV visible spectra of mixed ligand metal complexes Sr. o. Compound Electronic spectra (nm) Magnetic moments π π* n π* L M μ eff B. M. H 2L C 20H (il X 2)n-H 2 C 38H i C 38H Cu Molar conductivity The molar conductivity (Λm) data of i(ii) and Cu(II) complexes ( ohm cm 2 mol )measured at 30 C using 0-3 M solutions of the complexes in DMF solvent. These low values indicate that all their complexes are non-electrolytes due to the absence of any counter ions in their structures. The molar conductance values of these complexes indicate that the Schiff base ligand is coordinated to the i(ii) and Cu(II), ions as a doubly negatively charged anions. Therefore, it seems that two phenolic H have been deprotonated and bonded to the metal ions as oxygen anion. Table 5: Thermal analysis of Cu(II) and i(ii)) Complexes by TGA/DTA method. ame of the complex H 2L C 20H TGA range (il X 2)n-H C 38H i above760 C 38H Cu above780 Stage I II III I II residue I II residue Mass loss % Evolved moiety o loss Amino phenolic group lost. Terephthalaldehyde group lost Loss of lattice water Removal of organic moiety Leaving i Loss of lattice water Removal of organic moiety Leaving Cu 77 L. V. Gavali and M. R. Jadhav

7 Table 6:Antimicrobial activity data of the ligands, and their Cu(II) and I(II) mixed ligand complexes. Schiff base /complexes Zone of inhibition(mm) B. Subtilis E. Coli S. Typhi S. Aureus H 2L C 20H (il X 2)n-H 2 C 38H i C 38H Cu Antimicrobial activity: Schiff base of terephthalaldehyde with 2-aminophenol and their Cu(II) and I(II) mixed ligand metal complexes was screened against various bacteria s to observed their activity as anti microbial activity by disc diffusion method. The zone of inhibition is measured around discs. The measured zone of inhibition against various microorganisms is tabulated in table 6. It shows that mixed ligand metal complexes shows higher antimicrobial activity than free ligand. Conclusion Binuclear complexes of i(ii) and Cu(II) of terephthalaldehyde and 2-aminonophenol Schiff base with 8- Hydroxy qunoline as second ligand was synthesized and characterized by various physico-chemical and spectroscopic methods. The bonding of Ligand through two azomethine nitrogen s and two hydroxyl oxygen s have been deduced by FT-IR, H MR spectral findings. The overall geometry of respective metal ions has been confirmed on the basis of electronic spectra and magnetic moment values. The antimicrobial activity on the ligand and its i(ii) and Cu(II) complex has shown that complex possess higher activity than free Schiff base ligand. References. S.. Pandeya, D. Sriram, G. ath and E. De Clercq, Pharm. Acta Helv., 74 (999). 2. H.K. Shapiro, Am. J. Ther., 5 (998) M.Singh, Curr. Pharm. Des., 5 (999) A. Elmali, M. Kabak and, Y. Elerman, J. Mol. Struct., 477 (2000) J.R. Anacona, E. Bastardo and, J. Camus, Trans. Met.Chem., 24 (999) U. Spichiger-Keller, Chemical Sensors and Biosensors for Medical and Biological Applications, Wiley-VCH, Weinheim, D.H. Brown and W.E. Smith, Enzyme Chemistry-Impact and Applications, Chapmann and Hall, London, P.G. Cozzi, Chem. Soc. Rev., 33 (2004) H. Schiff, Ann. Chem. Pharm., 50 (869) C. K. Jørgensen, Acta Chem. Scand., (957) 73.. L.V.Gavali, and V.S.Shivankar. ISR Journal of Applied Chemistry, Vol.3,6 (203) V. Cassellata, P. Vigato, D.E. Fenton and M. Vidali, Chem. Soc. Rev., 79 (979) J. Sessler and J. Sibcr, Tetrahedron, 49 (993) M. Yildiz, Z. Kilic and T. Hökelek, J. Mol. Struct., 44 (998). 5. Y. Sunatsuki, Y. Motoda and. Matsumoto, Coord. Chem. Rev., 226 (2002) M. Usharani, E. Akila, P. Jayaseelan and R. Rajave, IJPP, Vol 5,Suppl L. V. Gavali and M. R. Jadhav