Syntheses and characterization of some homodimer complexes of bismuth(III) having a Bi horizontal ellipsis Bi linkage along with molecular modeling, antimicrobial, antioxidant and cytotoxic studies

A homodimer of bismuth(III) heteroleptic derivatives having two ligands, [{(R-1)(R-2)C = NO}(2)Bi{S2CN(CH2CH2)(2)O}](2) [where R-1 = -C6H5, R-2 = -CH3 (1); R-1 = -C6H4CH3, R-2 = -CH3 (2); R-1 = -C6H4Cl, R-2 = -CH3 (3); R-1 = -C6H4Br, R-2 = -CH3 (4); R-1 = -C6H4OH, R-2 = -H (5); R-1(R-2)C = C-CH2-(CH2)(3)-CH2 (6)], were synthesized by reaction of bismuth(III) chloride with sodium substituted oximes and morpholine dithiocarbamate in 1:2:1 stoichiometry. The complex was characterized by IR, H-1 and C-13 NMR spectra; the dimeric structure was assigned through LC-mass spectrometry. Distorted octahedral geometry around the central bismuth in each unit of the homodimer, linked by Bi horizontal ellipsis Bi bond, is proposed. Calculations for the two possible optimized geometries were done to determine Bi horizontal ellipsis Bi intermolecular linkage in these derivatives. Powder XRD study displayed nano range (similar to 30 nm) particle size and crystalline nature. The synthesized bismuth(III) derivatives were studied against four microbes viz., Bacillus subtilis, Escherichia coli, Aspergillus niger and Candida albicans. The antioxidant evaluation was carried out by FRAP assay and the cytotoxic study was accomplished through MTT analyzer. The results revealed that these derivatives were non-toxic (>50% cell viability) for 3 T-3 fibroblast cell lines even at 500 mu g/mL concentration.