Abstract

Five Schiff base complexes, namely [FeL2(H2O)2] (1), [CoL2(H2O)2] (2), [NiL2] (3), [CuL2] (4), and [ZnL2] (5) were synthesized and characterized via solubility, melting points, molar conductivity, magnetic susceptibility, UV-Vis and IR spectroscopies. The complexes showed a metal-to-ligand ratio of 1:2 and were observed to be non-electrolytic, as per the results of molar conductivity tests. The IR spectra showed that the coordination between the carbonyl groups, the methanolic oxygen atom of the Schiff base, and the metal centers occurred in a bidentate manner. Electronic spectra and magnetic susceptibility tests revealed that complexes 1 and 2 had an octahedral geometry with a six-coordinate local symmetry around the metal ions. In contrast, complexes 3–5 were observed to be square planar. Studies on magnetic susceptibility further showed that complexes 3 through 5 are paramagnetic, whereas complex 5 is expectedly diamagnetic. As a result of forming high spin complexes with Fe(II) and Co(II) ions, the results further revealed that the Schiff base ligands are weak field ligands. The antimicrobial tests revealed that the metal complexes had more inhibition activity when compared to the free ligands. Thus, the Schiff base complexes have potential as powerful, all-purpose antimicrobial agents.