Synthesis and structures of 3-nitro-salicylaldehyde-N-substituted thiosem-icarbazonates of copper(II): Novel bio-active materials against E. faecalis, E. coli, and K. pneumoniae

Abstract

A series of equimolar reactions of 3-nitro-salicylaldehyde-N1-substituted thiosemicarbazones, (3-NO2-stscH2-N1HR; R = H, Me, Et, Ph; stsc - stands for salicylaldehyde thiosemicarbazone), with copper(II) acetate in the presence of 2, 2-bipyridine (bipy)/1,10-phenanthroline (phen) as co-ligands, have yielded five-coordinate complexes of stoichiometry, [Cu(3-NO2-stsc-N1HR)(N,N-L)] {L, R : bipy, H, 1; Me, 2; Et, 3; Ph, 4; phen, H, 5; Me, 6; Et, 7; Ph, 8}. These complexes have been characterized using elemental analysis, electronic absorption and X-band ESR spectroscopy, ESI-mass study and single crystal X-ray crystallography (for 2, 4). The geometry of complexes 2 and 4 is distorted square pyramid as revealed by the distortion parameter, τ, which falls in the region, τ = 0.332–0.345 (complex 2) and = 0.386 (complex 2). These 3-nitro copper complexes have shown significant antimicrobial activity against Enterococcus faecalis (MTCC 439), Escherichia coli (MTCC 119), methicillin resistant Staphylococcus aureus (MRSA), Staphylococcus aureus (MTCC740), Klebsiella pneumoniae 1 (MTCC109), and a yeast, Candida albicans (MTCC227).