Characterization, crystal structures, electrochemical and antibacterial studies of four new binuclear cobalt(III) complexes derived from o-aminobenzyl alcohol

• Cobalt(III) complexes showed moderate antibacterial activity.
• Four new bi-nuclear cobalt(III) Schiff base complexes were investigated.
• The crystal structures were determined by X-ray diffraction.

Four new binuclear cobalt(III) complexes of tridentate Schiff base ligands, [Co2III(L1)2(py)2(OAc)]PF6 (1), [Co2III(L2)2(py)2(OAc)]PF6 (2), [Co2III(L1)2(4-Mepy)2(OAc)]ClO4 (3), [Co2III(L2)2(4-Mepy)2(OCH3)]PF6 (4) were synthesized by reaction of the respectively tridentate ligands (H2L1 = 2-[(2-(hydroxymethyl)phenylimino)methyl]phenol, H2L2 = 2-[(2-(hydroxymethylphenyl)iminomethyl)phenol]6-methyl phenol) with the corresponding cobalt(II) acetate in the presence of pyridine or 4-Mepyridine. These complexes were characterized by FT-IR, 1H NMR, Elemental Analysis and UV–Vis spectroscopy. All complexes were non-electrolyte in methanol solution as evident from low value of molar conductance in the range 46–76 Ω−1 cm2 mol−1. The crystal structures of the 1, 2 and 4 complexes were determined by X-ray crystallography and it was found that the geometry of Co(III) ion is distorted octahedral in these complexes. Cyclic voltammetry studies revealed that all of the complexes showed two reduction waves related to CoIII/II and CoII/I couples. The antibacterial effectiveness of the complexes was confirmed against, Staphylococcus aureus, Salmonella Typhi, Escherichia coli and Bacillus subtilis by the well diffusion method.

Some novel binuclear cobalt(III) complexes of tridentate Schiff bases were prepared and investigated. These complexes were characterized by various spectroscopic techniques. The crystal structures of 1, 2 and 4 were determined by X-ray diffraction. Cyclic voltammetry studies revealed that all of the complexes showed two reduction waves related to CoIII/II and CoII/I couples. The complexes were also screened for in vitro antibacterial activities against four human pathogenic bacteria and their minimum inhibitory concentrations were determined.Figure optionsDownload as PowerPoint slide