Cobalt(II) Benzazole Derivative Complexes: Synthesis, Characterization, Antibacterial and Synergistic Activity

In this study, we synthesized the cobalt(II) chelation free complexes (1-3) with the general formula of [CoCl2L2] containing monodentate ligands (L=2-methylbenzimidazole (L1), 2-methylbenzoxazole (L2), and 2-methylbenzothiazole (L3) and fully characterized by UV-vis, FT-IR spectroscopy, and the crystal structures of 1-3 were determined by X-ray crystallography. Complexes 1-3 showed substantial antibacterial activity against tested bacteria. Complexes 2 and 3 were more active against S. aureus with the Minimum Inhibitory concentration (MIC) value of 12.5 mu g/mL compared to other bacteria. Complexes 1-3 exhibited strong synergy with ampicillin (AMP) against Methicillin Resistant S. aureus strains (MRSA). Interestingly, complexes 2 and 3 in combination with AMP showed the membrane permeabilization of MRSA. This indicates that complexes 2 and 3 in combination with AMP had bacterial membrane disruption as a possible mechanism of action.