Synthesis, characterization and antimicrobial activity of mixed transition metal complexes of salicylic acid with 1, 10-phenanthroline

Abstract

A new series of Mn(II), Fe(II), Co(II), Cu(II) and Zn(II) mixed ligands-metal complexes derived from salicylic acid (SA) and 1,10-phenanthroline (PHEN) have been synthesized and characterized by spectroscopic studies. The coordination of the two ligands towards central metal ions has been proposed in the light of elemental analysis, IR, UV–vis spectroscopic studies. The results of the physical and spectroscopic data confirmed that the ligands are chelating agents. In 1, 10-phenanthroline, coordination occurred through the two pyridinic nitrogen groups, while in the salicylic acid coordination occurred through the oxygen of the hydroxyl and the carboxylic groups. All the complexes synthesized were of octahedral geometry. Antimicrobial activity of the mixed ligands metal complexes and the free ligands were carried out against the bacterial Escherichia coli, staphylococcus aureus, klebsiella pneumonia, pseudomonas aeruginosa and the fungi candida spp. The mixed ligands metal complexes showed higher activities when compared to the free ligands of salicylic acid but were less active than the free 1,10-phenanthroline ligand. The complexes of Cu (II) showed the highest antimicrobial activity while the Fe(II ) complex showed the least activity against the bacterial and fungi organisms.

Keywords: 1,10-phenanthroline, Salicylic acid, Mixed ligands-metal complexes, Transition metal, Spectroscopy, Antimicrobial