Superoxide scavenging and antimicrobial activities of novel transition metal complexes of oxydiacetate dianion as primary ligand: Spectral characterization, cyclic voltammetric investigations and crystal structure

Abstract

Complexes of stoichiometries [M(oda)(4-pic)H2O]·xH2O [M = Cu(1), x = 2; Co (2), x = 4; Ni (3), x = 2; ] [Fe(oda)(4-pic)]·Cl (4) and {[Cu(2-pa)2]·2H2O}n (5) (H2oda = oxydiacetic acid, 4-pic = 4-picoline and 2-paH = 2-picolinic acid) were prepared to explore their uses as possible models for mono- and poly-nuclear metallo-pharmaceuticals. The chemical structures were elucidated by IR, FAB-Mass, 1H, 13C NMR, EPR and UV–visible (ligand field) spectral analyses. Electrochemical investigations are consistent with formation of stable quasi-reversible redox CoII/III and CuII/III couples in the solution. Single crystal X-ray data of the complex (5) indicated a 1D coordination polymeric structure with extensive H-bonding to form supramolecular frameworks. The antimicrobial activities were examined against Escherichia coli (k-12), Bacillus subtilis (MTC-121), Staphylococcus aureus (IOASA-22), Salmonella typhimurium (MTCC-98), Candida albicans, Aspergillus fumigatus and Penicillium marneffei. The superoxide dismutase (SOD) activities of the Cu(II) complexes (1 and 5) were assessed employing nitrobluetetrazolium (NBT) assay.