Synthesis,characterization and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes involving a potentially tetradentate Schiff base ligand

Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from vanillinidene-4-aminoantipyrine and o-phenylenediamine were synthesized and characterized by elemental analysis, ¹H-NMR, ¹³C-NMR, molar conductance, infrared, electronic, magnetic measurements, cyclic voltammetry, powder XRD and SEM. The IR results demonstrate that the co-ordination sites are the four azomethine nitrogen atoms. The electronic spectral and magnetic measurement data indicate that the complexes exhibit octahedral geometry. Powder XRD displays the crystalline nature of Co(II) and Zn(II) complexes. The SEM images reveal that all the complexes have almost similar morphologies with broken-stone like structure. The in vitro biological screening effects of the synthesized compounds were tested against the bacterial species, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus; fungal species, Aspergillus niger, Aspergillus flavus and Candida albicans by the disc diffusion method and the results show that the metal complexes are more biological active than the ligand.