Synthesis, structural investigation and biological application of new mono- and binuclear cobalt (II) mixed-ligand complexes containing 1,10-phenanthroline, acetamide and ethylenediamine

The intensive use of antibiotics has led to an increase of drug resistant bacteria against known antibiotics. To overcome the alarming problem of microbial resistance to antibiotics, the discovery of novel active compounds against new targets is a matter of urgency. Based on this, we report three new mixed ligand complexes of cobalt (II) viz. mononuclear ([Co(phen) 2 (Act)(H 2 O)]Cl 2 .H 2 O and [Co(phen) 2 (Act)(en)]Cl 2 ), and binuclear [Co 2 (phen) 4 (Act) 2 (en)]Cl 4 which were synthesized from CoCl 2 .6H 2 O, 1,10-phenanthroline monohydrate, acetamide and ethylenediamine. These complexes were characterized using spectroscopic (ESI-MS, ICP-OES, FT-IR, and UV-Vis), chloride determination as well as melting point and conductance measurement. Invitro antibacterial activity was also tested on two Gram positive ( Staphylococcus aureus , Streptococcus pyogenes ) and two Gram negative ( Escherichia coli and Klebsiella pneumoniae ) bacteria using disc diffusion method. The complexes performed well even against the Gram-negative bacteria. The antibacterial result was found comparable with the commercial drug Gentamicin even at lower concentration of complexes. Thus, the synthesized complexes may be considered as potential antibacterial agents after passing cytotoxicity testing.