Mono-and Binuclear Cobalt(II) Mixed Ligand Complexes of 2,2’-Bipyridine and Ethylenediamine: Synthesis, Characterization and Biological Application

Abstract

Antibiotic resistance of pathogens to the current commercially available drugs is a serious problem. To curve this problem, the discovery of active compounds with a new mode of action is insistent. In line with this, we report two new complexes; mononuclear [Co(L1)2(L2)(H2O)]Cl2 and binuclear [Co2(L1)4(L2)(H2O)2]Cl4 using precursor complex, [Co(L1)2(H2O)2]Cl2, synthesized before; where L1: 2,2’-bipyridine and L2: ethylenediamine. The precursor complex was prepared from CoCl2.6H2O and L1 in ethanol, treated with a different mole of L2 under optimized reaction conditions to give the corresponding mono-and binuclear cobalt(II) mixed ligand complexes. These complexes were characterized using the spectroscopic technique (ICP-OES, UV-Vis, FT-IR) and physicochemical methods (chloride determination, thermal analysis, and conductance measurement). Their antibacterial activities were also tested against two Gram-negative (Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae)) and two Gram-positive (Staphylococcus aureus (S. aureus), Streptococcus pyogenes (S. pyogenes)) bacteria using the disc diffusion method. The new complexes showed better activities against K. pneumoniae than the reference Gentamycin. Furthermore, [Co(L1)2(L2)(H2O)]Cl2 demonstrated better activity than Gentamycin against S. aureus and E. coli.