Synthesis, Characterization and Antimicrobial Activities of Co(II) Complex of the Schiff Base Ligand Derived from 4-Acyl Antipyrine

Abstract

The incidence of drug- resistant microbial infections is a growing concern worldwide, necessitating the development of novel antimicrobial agents that would break barrier of resistance, guarantee safety and potency of pharmaceutical products. This study aimed to synthesize, characterize, and evaluate the antimicrobial activities of a Schiff base ligand derived from acetyl chloride antipyrine (4- acyl antipyrine) and substituted 2- hydroxyl aniline and its Co(II) complex, in order to explore their potential as antimicrobial agents. The ligand was synthesized by condensing 4-acyl antipyrine with 2-hydroxyl aniline in ethanol, while the Co(II) complex was prepared in a 1:2 metal-to-ligand ratio. The synthesized compounds were characterized using FTIR, UV-Vis, GCMS and XRD techniques. Interestingly, all the synthesized compounds were obtained in good yield (78%-86%). The spectroscopic and diffraction studies confirmed successful coordination via nitrogen and oxygen donor atoms, with characteristic shifts indicating complex formation. The Schiff base ligands SLOA (1,700.65cm-1) showed a notable shift to higher wavenumbers indicating increase C=O bond strength due to coordination with metal through its oxygen. metal complex shows C=O stretching shifted back to lower frequency value (1.633.54cm-1) suggesting co-ordination of oxygen to metal. Antimicrobial activity was evaluated using agar diffusion and broth dilution methods against various bacterial and fungal strains. The results revealed that the metal complex, exhibited enhanced antimicrobial efficacy compared to the ligands. Notably, the cobalt complex showed enhanced activity against Salmonella typhi, Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes, and Candida albicans. The findings highlight the significance of metal chelation in improving biological activity and support the potential of Co(II) complex and its Schiff base ligand as an effective antimicrobial agent.