ISONICOTINOHYDRAZIDE DERIVED SCHIFF BASE–TRANSITION METAL COMPLEXES: STRUCTURE WITH BIOLOGICAL ACTIVITY

resistance is increasingly becoming a prominent global public health and developmental concern. The primary aim of this study is to synthesize metal complexes with superior antimicrobial properties. Methods: The Schiff base ligand (E)-N'-(1-thiophen-2-yl) ethylidene isonicotinohydrazide was synthesized by reacting isonicotinohydrazide (INH) with 2-acetylthiophene. This Schiff base was utilized to synthesize metal complexes with copper (II), nickel (II), and cobalt (II) ions via the reflux method. The ligand and metal complexes were characterized using various physicochemical techniques, including elemental analysis, conduct metric studies, magnetic susceptibility, FT‐IR, 1H NMR, ESI-MS, and electronic spectral analysis. Results: All complexes were successfully characterized. The Ni-complex demonstrated the highest cytotoxicity in the brine shrimp lethality bioassay compared to the Cu and Co-complexes. The Ni and Cu-complexes exhibited greater antibacterial efficacy against all bacteria, while the Co-complex showed no activity. Conclusion: The newly synthesized complexes proved to be highly stable, displaying significant antimicrobial potential. These findings suggest that future modifications to this synthesized series could address specific pharmaceutical needs.