Co(II), Ni(II), Cu(II), and Zn(II) complexes derived from 4-[{3-(4-bromophenyl)-1-phenyl-1H-pyrazol-4-ylmethylene}-amino]-3-mercapto-6-methyl-5-oxo-1,2,4-triazine

A new series of Co(II), Ni(II), Cu(II) and Zn(II) complexes were prepared with bidentate ligand derived by condensation of 4-amino-3-mercapto-6-methyl-5-oxo-1,2,4-triazine with 3-(p-bromophenyl)-1-phenyl-1H-pyrazolecarboxaldehyde. The Schiff base and its metal complexes were characterized on the basis of various spectroscopic investigation like IR, NMR, fluorescence and thermal analyses. The coordinated water molecules were confirmed by IR and thermal data, while the geometry of the complexes was confirmed by electronic spectra, magnetic moment measurements and ESR analysis. Cyclic voltammetry shows the redox behavior of copper complexes. All the complexes were colored, stable in air and non-electrolytic in nature. Schiff base and its metal complexes were screened for in vitro antimicrobial activity and it was observed that metal complexes show enhanced biological activity as compared to ligand or metal salts. In addition, Zn(II) complexes show enhanced biological activity against most of the microbial strains as compared to ligand and other metal complexes