Bioactive mixed ligand metal complexes of CU(II), NI(II), and ZN(II) ions: Synthesis, characterization, antimicrobial and antioxidant properties

Abstract

A series of transition metal complexes having general formula [M(L1)(L2)](NO3)2, (where, M = Cu(II), Ni(II), and Zn(II)) of mixed ligands, L1 = Isonicotinamido-Thiophene-2-Carbaldimine, L2 = 1, 10-phenanthroline, were synthesized. The obtained compounds were successfully characterized by different spectroscopic techniques. Conductivity measurements indicated that all complexes were 1:2 electrolytes in nature. IR spectra indicated that ligands coordinated to metals via the carbonyl oxygen atom and the azomethine nitrogen atom. Magnetic moment values and UV-Visible spectra confirmed square planar structure around the Cu(II), and Ni(II) ions, and a tetrahedral geometry around the Zn(II) ion.The metal complexes were tested against Escherichia coli and Pseudomonas sp. Among the tested compounds, Zn(II)complex showed higher antibacterial activity over both bacterial strains against reference drug Kanamycin. Moreover, synthesized metal complexes exhibited moderate antioxidant activity than the Schiff base. Cu(II) complexes were found to be most active whereas, Zn(II) complexes showed the lowest antioxidant activity comparable to the BHT.