Design, Synthesis, Spectroscopic and Physicochemical Characterization, and Biological Potency Screening of the Tridentate-Capable Hydrazone Schiff Base (E)-N'-(2-Fluoro-6-hydroxybenzylidene)-4-methoxybenzohydrazide and Its Ni(II), Co(II), Cu(II), Pd(II), Mn(II), Fe(II) Coordination Compounds

Abstract

The present investigation describes the successful synthesis and detailed physicochemical characterization of a new hydrazone-based ligand, (E)-N′-(2-fluoro-6-hydroxybenzylidene)-4-methoxybenzohydrazide, together with its coordination complexes formed with nickel(II), cobalt(II), copper(II), palladium(II), manganese(II), and iron(II) ions. Structural elucidation of the ligand and its metal complexes was accomplished using a combination of spectroscopic techniques, including FT-IR, 1H and 13C NMR spectroscopy, and mass spectrometry, which collectively confirmed effective metal coordination and complex formation. The antimicrobial potential of the free ligand and the corresponding metal complexes was systematically assessed against a panel of clinically relevant bacterial and fungal pathogens. In comparison to the uncoordinated ligand, the metal complexes demonstrated markedly enhanced antibacterial and antifungal activities, as evidenced by significantly larger inhibition zones against both Gram-positive and Gram-negative bacterial strains, as well as fungal species. The observed enhancement in bioactivity upon metal coordination underscores the role of chelation in modulating biological performance. This study contributes valuable insights into the structure-activity relationships of hydrazone-based metal complexes and highlights their promise as potential antimicrobial agents, thereby reinforcing their relevance within the expanding domain of bioinorganic chemistry and therapeutic agent development.