Schiff base metal complexes of 4-(2-Chloro-5-nitrobenzylideneamino)-5-mercapto-3-methyl-1,2,4-triazole: Synthesis, characterization, electron spin resonance, fluorescence, and biological study

Abstract

The Schiff base, 4-(2-Chloro-5-nitrobenzylideneamino)-5-mercapto-3-methyl-1,2,4-triazole (HL) was prepared by refluxing 4-Amino-5-mercapto-3-methyl-1,2,4-triazole and 2-Chloro-5-nitrobenzaldehyde in equimolar concentrations. The synthesis of Cu(II) and Zn(II) complexes was carried out using the Schiff base in 1:1 and 1:2 molar ratios. The synthesized ligand and metal complexes were characterized through spectral studies (UV-vis, IR, 1H-NMR, ESR, Fluorescence), elemental analysis, and thermal and magnetic moment measurements. An octahedral geometry for the Zn(II) complex and a square planar geometry for the Cu(II) complex were proposed based on the results of spectral and thermal techniques. The presence of coordinated water in the 1:1 metal complexes was confirmed using Infrared and Thermogravimetric methods. The antimicrobial activity of the Schiff base and its metal complexes was assessed against gram positive bacteria (Bacillus subtilis, Staphylococcus aureus), gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and yeast (Candida albicans and Saccharomyces cerevisiae) to evaluate their antimicrobial activity.