Aqueous anion binder for phenolate and nitro substituted phenolates through second-sphere coordination network

Abstract

A series of four cobalt(III) complexes, [Co(Hbig)3]1.5Cl3.5(Ph).2H2O (1), [Co(Hbig)3] (PNP)3.H2O (2), [Co(Hbig)3](DNP)3.H2O (3) and [Co(Hbig)3](TNP)3·4H2O (4) have been synthesized by reacting [Co(Hbig)3]Cl3.H2O (Hbig: biguanide) with sodium phenolates (Ph: pheonlate, PNP: 4-nitrophenolate, DNP: 2,4-dinitrophenolate or TNP: 2,4,6-trinitrophenolate) in 1:3 molar ratio in aqueous medium. All the complexes were initially characterized by physiochemical and spectroscopic (UV–Visible, IR and NMR) studies. Anion binding affinity of complex cation for anions has been studies in aqueous medium using UV–Visible spectroscopic titrations and found log β values for anions. The single crystal X-ray structures of complex 3 and 4 were also determined and stacking of layers has been observed in both the structures. These stacking layers contains layers of [Co(Hbig)3]3+, nitro-phenolate (DNP or TNP) and water molecules along b-axis. These layers connected with one another by numerous intermolecular N-H…O hydrogen bonds leads to formation of second-sphere coordination network. Further, all the complexes and their respective reactants have been tested for antimicrobial activities against strain of Gram negative (P. aeruginosa, E. coli, K. pneumoniae, S. typhi), strain of Gram positive bacteria (B. subtilis, S. epidermidis) and antifungal against C. herbarum, A. alternata and F. oxysporum.