EXPLORING THE ANTIFUNGAL POTENTIAL OF Co(II) AND Mn(II) SCHIFF BASE DERIVED FROM o-AMINOPHENOL AND BENZALDEHYDE COMPLEXES, SYNTHESIS, SPECTROSCOPIC STUDIES

A Schiff base derived from benzaldehyde and o-aminophenol was synthesized, along with its Mn(II) and Co(II) complexes. The synthesized compounds were characterized using standard analytical and spectroscopic methods, including melting/decomposition temperature determination, solubility testing, magnetic susceptibility, infrared (IR) spectroscopy, atomic absorption spectroscopy (AAS), and elemental analysis. Formation of the azomethine bond was confirmed by an IR absorption band at 1614 cm⁻¹ for the free ligand, which shifted to 1603 cm⁻¹ and 1602 cm⁻¹ in the metal complexes, indicating coordination. The melting point of the Schiff base was 189 °C, while the metal complexes decomposed at 273 °C and 220 °C, respectively. Magnetic moment values of 5.78 and 4.81 B.M confirmed paramagnetic behavior. Low molar conductance values (18.5 and 14.1 Ω⁻¹ cm² mol⁻¹) indicated non-electrolytic nature of the complexes. AAS and elemental data suggested a 1:2 metal-to-ligand ratio, with the Schiff base functioning as a bidentate ligand. Biological evaluations revealed that the Schiff base and its metal complexes exhibited significant antibacterial activity against Staphylococcus aureus, Escherichia coli, and Salmonella typhi, and potent antifungal activity against Aspergillus niger, Aspergillus flavus, and Candida albicans. Notably, the antifungal effects were more pronounced at higher concentrations. Cytotoxicity studies showed moderate toxicity, with LC₅₀ values of 132.705 and 147.932 µg/mL for the free ligand and complexes, respectively. These findings suggest that Schiff base metal complexes of Mn(II) and Co(II) hold promise as effective bioactive agents, particularly in antifungal applications.