10th U6+ Consortium of African Universities International Conference

New transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) were successfully synthesized with Schiff base ligands formed by the condensation of isonicotinic acid hydrazide with indoline-2,3-dione and 4-hydroxy-3-methoxybenzaldehyde. The complexes were obtained in moderate yields as coloured solids with sharp melting points. Comprehensive characterization was carried out using physicochemical and spectroscopic techniques. Molar conductance measurements indicated low values, confirming the non-electrolytic nature of the complexes. Infrared spectral analysis revealed that the Schiff base ligands generally acted as bidentate donors coordinating through the azomethine nitrogen and carbonyl oxygen atoms, except in the Cu(II) complexes where the ligands behaved as tridentate ONO donors. Electronic spectral data suggested that the Mn(II), Co(II), Ni(II), and Zn(II) complexes adopt tetrahedral geometries, while the Cu(II) complex exhibits an octahedral geometry. The in vitro antibacterial and antifungal activities of the synthesized compounds were evaluated against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans using the disc diffusion method. Several metal complexes showed notable antimicrobial activities, and in all cases the metal chelates displayed enhanced activity compared to the free Schiff base ligands. Overall, the successful synthesis, spectral characterization, and antimicrobial evaluation of the Schiff base ligands and their corresponding metal (II) complexes have been demonstrated.