Indian Academy of Sciences, 82 nd Annual Meeting, 5 th Nov 2016, IISER Bhopal

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1 Recognition, Sensing and Separation of Anions Pradyut Ghosh Department of Inorganic Chemistry Indian Association for the Cultivation of Science 2A & 2B Raja S. C. Mullick Road, Kolkata Indian Academy of Sciences, 82 nd Annual Meeting, 5 th ov 2016, IISER Bhopal

2 J. Am. Chem. Soc. 2006, 128, 9600 Inorg. Chem. 2011, 50, 4772 Inorg. Chem. 2013, 52, 4269 Inorg. Chem. 2015, 54, 4231 Ion Sensing Inorg. Chem. 2010, 49, 4447 Chem. Commun. 2010, 46, 2962 Dalton Trans. 2011, 40, Org. & Biomol. Chem. 2011, 1972 Dalton Trans. 2011, 40, 6411 Inorg. Chem. 2011, 50, 4229 Inorg. Chem. 2014, 53, 8061 Inorg. Chem. 2016, 55, 259 Inorg. Chem. 2016, 55, 9212 Chem. Eur. J. 2016, 23, 0000 Research in my Group Self-Assembly Interlocked Molecules Basic Science: Coordination chemistry of anions Anion Recognition Potential Applications: Development of Selective Anion Receptor towards Chemical Separation Clean Environment Safe Water Chemical Sensing Chem. Commun. 2011,47, 6272 Chem. Eur. J. 2011, 17, Eur. J. Inorg. Chem. 2014, 2029 J. Org. Chem. 2014, 79, Org. Lett. 2015, 17, 1854 Dalton Trans. 2015, 44, 15198

3 The obel Prize in Chemistry 1987 UCLA, USA U. Louis Pasteur, France Du Pont, USA Anions A n- Hydrogen Bond Lewis acid hydrogen bonds

4 Factors that Regulate and Complicate Recognition Size (larger than cations) and shape (more diverse) ph Solvation of anions plays a very important role. Anions generally have very high solvation energies that must be compensated by the host. Thus when possible, anion binding should be carried out in apolar solvents or create a microenvironments.

5 Our Approaches CAPSULE Enclose Space Size Function SYTHESIS + + +

6 Building Blocks for Our Receptors Designing Platforms Recognition Elements O S O S Weak Interactions H H H H Attached Units H H H H -H Anion C-H AnionAnion H H

7 Covalent Capsules towards Anion Recognition Lehn et al elson et al Martell et al Ghosh et al Ghosh et al H H H H H H H H H 6.37 Å H H H 7.58Å 12.19Å Å 11.10Å J. Am. Chem. Soc. 2005, 127, ; Inorg. Chem. 2005, 44, 4, 7540; 0;Angew. Chem. Int. Ed. 2006, 118, 3891; Inorg. Chem. 2006, 45, 10046; Cryst. Growth Des. 2006, 6, 2630; Tetrahedron 2007, 63, 11371; Inorg. Chem. 2008, 47, 7992 ; J. Org. Chem. 2008, 73, 9144; Cryst. Growth Des. 2008, 8, 2842; Cryst. Growth Des. 2013, 13, 3208J. Org. Chem. 2013, 78, 8759.

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9 Moving towards half-capsule 4 H4C 3 H3D H2C 2 Br Bowman an-james et al.; Inorg rg. Chem. 2004, 43, 3751 C 2g C 1g Anion Log K Cl Br F F F F F F F F F F F F F F F Inorg. Chem. 2006, 4372; Inorg. Chem. 2007, 4769; Inorg. Chem. 2011, 1,10693; Eur. J. Inorg. Chem. 2012, 3546; Inorg. Chim. Acta 2010, 2886; CrystEng.Com. 2014, 4796.

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11 H H H H O O O H H R R R H H H R O O O R R H H H R R R Recognition Element: Dimensionality Bicyclic amine cage

12 Anion Assisted Capsular Assemblies Chem. Commun. 2007, 5214; Dalton Trans. 2009, 4160; Chem. Commun. 2011, 47, 8477 (Feature Article); Chem. Commun. 2014, 50, (Feature Article).

13 Solution State Anion Binding Study by ITC Guest n TS H G log K log K kcal/mol kcal/mol kcal/mol (ITC) (MR) F - SO H 2 PO CO CH 3 CO F Cl Br AcO - H 2 PO 4 - CO 3

14 Arsenate Recognition in Aqueous Medium Table 1. Association constant value of L in DMSO-d 6 /D 2 O (9:1, v/v) with different anion in DMSO-d 6 /D 2 O (1.1:1, v/v) at 298 K Anion log K log K a log K b HAsO H 2 PO SO CO a: log K value calculated in buffered condition, b: log K value calculated in DMSO-d 6 solvent Dalton Trans. 2013, 42,11371

15 Benzene platform based tripodal amides Chem. Commun., 2009, 5389 (Hot article) e); Inorg. Chem. 2010, 0, 49, 943; Dalton Trans. 2014, 43, 2061; Chem. Commun. 2015, 51, 9070 (Feature article).

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17 Hexaamide for Compartmental Recognition [L][ -CH ] [L]/[L]+[F - ] Org. Lett. 2010, 0, 12, 328; Chem. Commun. 2011, 47, 6269; RSC Adv. 2014, 4, ; RSC Adv., 2015, 5,

18 Halogen Bonding Assisted Anion Recognition Synthetic Scheme Ligand Anions Association constants (log K) (kj/mol ) 1b Cl Br I O AcO

19 HB Versus XB: ITC studies Host Guest Stoichi Association ometry constants (K, M -1 ) (kj/mol) (kj/mol) (kj/mol) 1a Cl 1:3 K1= 6.00*10 4 K2= 9.43*10 3 K3= 9.55*10 2 (5.40 ± 0.4)* = = = = =8.1 3 = 11.0 K1= 5.93* = = a Br 1:3 K2= 1.61* = =15.9 K3= 1.16* = =4.6 (1.11 ± 0.08)*10 13 K1= 5.41* = = 1a I 1:3 K2= 2.62* = K3= 7.51* = =9.5 ( )* =-4.6 1b Cl 1:1 1.37* b Br 1:1 3.35* MP Cl 1:1 K = 2.12* MP Br 1:1 K = 2.66* MP I 1:1 K = 1.49* = = = = = = = = =-10.7 Tuning the selectivity from Cl to Br via halogen bonding with association constant (logk 1 ) 5.77 with Br.

20 Single crystal X-ray structural proof Bromide Complex Chloride Complex Chem.Commun., 2015, 51,

21 Bromide removal in presence of interfering anions 1a + {(TBABr + TBACl); (w/w = 1:1)} 1a + {(TBABr + TBACl); (w/w = 1:4)} 1a + {(TBABr + TBACl); (w/w = 1:9)} 1a + TBA salts of Br, Cl, I, ReO4, AcO, HSO4, O3 Bromide Complex Bromide Complex Bromide Complex Bromide Complex Chloride removal in presence of interfering anions 1a + TBA salts of Cl, I, ReO4, AcO, HSO4, O3 Chloride Complex

22 Potential Applications Capturing aerial CO 2 as CO 3 in a dimeric capsule Liquid-Liquid extraction of SO 4 / CrO 4 / F - Liquid-Liquid extraction of KF / KCl Solid-Liquid extraction of KBr

23 Capturing aerial CO 2 as CO 3 in a capsule CO and rising by about 2.0 ppm/yr. Base DMSO CO 3 H 2 O : MeOH Aerial CO 2 (%) L L Recycled L + CO L L L Amide stretching frequencies of L: 1664 cm -1 (amide I) and 1649 cm -1 (amide II); CO 3 Stretching Frequencies of complex: 1377 cm -1 (asymmetric) & 1688 cm -1 (symmetric) Chem. Commun. 2010, 0, 46, 1082

24 Highly Efficient & Clean Extraction of Sulfate Carbonate capsules of L as an extractant L 2 (CO 3 ) can be easily synthesized in very high yields. L 2 (CO 3 ) is good soluble in non-polar organic solvents. L 2 (CO 3 ) has relatively low association constant than L 2 (SO 4 ) CO 3 Capsule Complex + 1 eqv. K 2 SO 4 1 eqv. Extraction CHCl 3 / H 2 O Org. Layer 16 hydrogen bonds Sulfate Extraction Visual Detection

25 Quantitative Analysis of Extracted Mass CO 3 Capsule + K 2 SO 4 1 eqv. 1 eqv. Extraction CHCl 3 / H 2 O Org. Layer Shaking BaCl 2 /H 2 O BaSO 4 o of expt. Wt. of carbonate capsule (mg) Wt. of K 2 SO 4 (mg) Wt. of extracted mass (mg) % of extraction Wt. of BaSO 4 (mg) % of extractio n Chem. Sci. 2012, 3, 1522; Chem. Soc. Rev. 2012, 41, 3077

26 Capsular Assembly/Disassembly/Reassembly CO 2 Sequestration as Carbonate SO 4 Extraction

27 Extraction Carbonate capsule of Pentafluorophenyl attached tris-urea Carbonate capsule of 3-cyanophenyl attached tris-urea Sulfate YES YES Thiosulfate O YES Phosphates O O Chromate O YES Arsenate O O Fluoride O O Basic ph eutral ph Eur. J. Inorg. Chem. 2014, 4134.

28 Dual-host Strategy for Salts Extraction KF/KCl Control Experiments o Extraction KF/KCl Receptor % of KF extracted % of KCl extracted L 1 IL IL L 2 IL IL L 1 + L Salts % extracted at ph 4.5 % extracted at ph 6.3 % extracted at ph 9.3 KF IL KCl IL Chem. Commun , 4721

29 Crystal Structures of Extracted Complexes (a) (b) 3 F O1 K1 K1 O2 3 2 Cl1 4 O4 O10 (c) (a) & (b) Monomeric structure of complexes 3 and 4 with partial atomlabeling and (c) 1-D polymer of complex 3. on acidic hydrogen atoms are omitted for clarity.

30 Dual Host Receptor for Ion-pair Ligands should be composed of metal ions as well as anion binding sites either separated by a spacer or integrated into a unit The design principle of L1 is as follows: (i) 18-crown-6 is known for its use as a K+ selective receptor via coordination of suitable numbers of ethereal oxygen atoms with K+ ions; (ii) Pentafluorophenyl substituted urea is popular for its use as a strong H-bond donor unit to anions (iii) the lipophilic character of the pentafluorophenyl moiety also enhances the probability of salt extraction through the bilayer membrane.

31 Anion Binding Studies of L 1 O 3 HSO 4 K a (M ) Solvent: CD 3 C, temperature 298 K, [L 1 ] = ~2. 0 mm, anions added as TBA salts [TBAX] mm, errors < 1 0%. 4 3

32 Cooperative Effect towards Anion Binding Anions Binding constant in presence of TBA + (K TBA+ ; M -1 ) Binding constant in presence of K + (K K+ ; M -1 ) K K+ / K TBA O HSO Highest cooperative effective observed for O Chem. Commun., 2015, 51,

33 Cooperativity study by ITC Binding of Cl - in absence of K + Binding of Cl - in Presence of K + TBACl n TS [cal mol -1 ] H [cal mol -1 ] G [cal mol -1 ] K a [ITC] Absence of K Presence of K

34 Dynamic Properties of Capsular Assemblies Acid/base Controlled Modulation of Capsular Size Temperature Dependent Opening and Closing of Capsule stopper Anion Assisted Assembly and Disassembly Processes

35 Capsular Size Modulation OH - H Å Dihydrogen Phosphate Pseudo-capsule Å Hydrogen Phosphate Capsule

36 Tripodal Urea Receptors on Cyanuric Acid Chem. Commun. 2010, 0, 46, 6741; Eur. J. Inorg. Chem. 2013, 2673.

37 SO 4 Capsule Assisted by TBA-cations ~14 Å ~17 Å Eleven Hydrogen bonds: Six -H O and Five C-H O H-bonds L L L L L L L L L L L Anion log K SO H 2 PO CH 3 COO Cl

38 2D-DOSY MR of Capsules system T (K) D (10-10 m 2 s -1 ) R (Å) Stokes-Einstein Equation (n-bu 4 + ) 2 SO L Complex L + n-bu 4 + H 2 PO L + n-bu 4 + CH 3 COO L + n-bu 4 + O L + n-bu 4 + Cl D = Diffusion Co-efficient, k = Boltzmann Constant, T = Temperature = Viscosity Co-efficient, R = Hydrodynamic radii + + heat + + Cool

39 Anion Assisted Assembly and Disassembly em. Commun(H (HCHO) n HBr in HOAc Br Br H aoh/dmf-h 2 O HO 3 Br L Encapsulated Water in itrate Zipped Staggered Dimer Chem. Commun., 2009, 3184; Cryst Growth & Des 2012, 12, 2097.

40 Industrial Application (a) Coke Plant (b) Blast furnace Water Cyanide is present in low concentration (~ 4 ppm) along with high content of chloride, sulfate, nitrate etc. Interference of huge amount of ammonia and chloride Toxicity limit of cyanide for human is 0.4 ppm and the Blast Furnace water can be recycled if the concentration falls down to 1.5 ppm Currently 12 millions of gallons/ day is wasted every day which costs around 16 crore rupees/ year

41 Sample Conc. (mol ol/ 1000 lt.) Feed Sample After 30 min BF-water standard standard % removal Sample Conc. mmol /Lt Feed Sample (ppm) After 0.5 hour After 1 hour After 2 hours After 3 hours After 4 hours After 24 hours % removal BF- Water BF- Water

42 Phosphates Sensing through C-HAnion and Halogen Bonding Interaction Phenanthroline and Triazole C-H based Integrated Ru(II) Complex exploiting C-H anion Interaction for Sensing of Phosphate. Development of Monopodal and Tripodal Ru(II) Complexes for sensing of phosphates Signalling Unit Monopodal C-I halogen bonding Analogue to compare between XB and HB interaction Anion recognition unit Monopodal C-H analogue, a weak non-covalent interaction Tripodal C-H analogue to get better sensitivity Inorg. Chem. 2014, 53, 8061; Inorg. Chem. 2016, 55, 259; Chem. Eur. J. 2016, 23, 0000.

43 Highlights Developed anion coordination chemistry Selective anion receptors Carbonate Cycle Aerial CO 2 sequestration as CO 3 capsules Liquid-Liquid extraction of SO 4 /CrO 42 /F - Extraction Cycle Liquid-Liquid extraction of KF/KCl OH - Arsenate encapsulation Å H + Acid/base Controlled Modulation of Capsular Size Å Temperature Dependent Opening and Closing of Capsule stopper Hydrated fluoride encapsulation Anion Assisted Assembly and Disassembly Processes Selectivity within the covalent capsule

44 Current Group members: Dr. Barun Jana (RA) Dr. Sourav Chakraborty(SRF) Bijit Chowdhury (SRF) Saikat Santra (SRF) Tamal Kanti Ghosh (SRF) Siddhartha Maji (JRF) Sanghamitra Sinha (JRF) Sourenjit askar (JRF) Somenath Bej (JRF) Mandira andi (JRF) Sayan Sarkar (JRF) Rajib Ghosh (JRF) Sahidul Mondal (JRF) Alumni (PhD) Dr. P. S. Lakshminarayanan Dr. I. Ravikumar Dr. M. Arunachalam Dr. B. isar Ahamed Dr. Purnandhu Bose Dr. Subrata Saha Dr. Ranjan Dutta Dr. Bidyut Akhuli Alumni (RA & Short term visitors) Dr. S. Marivel Dr.. Haridharan Dr. Snehadrinarayan Khatua Dr. Arnab Maity Dr. Milan Bera Dr. Sandip Mukherjee Financial Support Swarnajaynti Fellowship SERB, DST CSIR Tata Steel IACS

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