Thermal, Spectral, Fluorescence, and Antimicrobial Studies of Cobalt, Nickel, Copper, and Zinc Complexes Derived from 4-[(5-Bromo-thiophen-2-ylmethylene)-amino]-3-mercapto-6-methyl-5-oxo-[1,2,4]triazine

Abstract

A new series of cobalt, nickel, copper, and zinc complexes of bidentate Schiff base derived from the condensation of 5-bromothiophene-2-carboxaldehyde with 4-amino-3-mercapto-6-methyl-5-oxo-[1,2,4]triazine were synthesized. Physical (magnetic measurements, molar conductance, TG), spectral (UV-Vis, IR, 1HNMR, fluorescence, ESR), and analytical data have established the structures of synthesized Schiff base and its metal complexes. The presence of coordinated water in metal complexes was confirmed by IR and TG studies. The Schiff base exhibits a strong fluorescence emission, contrast to this partial fluorescence quenching phenomena is observed in its metal complexes. A square planar geometry for Cu(II) and octahedral geometry for Co(II), Ni(II) and Zn(II) complexes have been proposed. The Schiff base and its metal complexes have been screened for antibacterial (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger, A. flavus).