Spectral and Thermal Characterization of Mn(II), Ni(II) and Zn(II) Complexes Containing Schiff Base Ligands Towards Potential Biological Application

Some metal complexes of Zn(II), Mn(II) and Ni(II) ions with tetradentate N, O coordinating Schiff base ligand [2-bis(2-hydroxybenzylidene)}hydrazinecarboxamide], (C15H13N3O3) were synthesized. The Schiff base ligand was derived from the condensation of semicarbazide hydrochloride and salicylaldehyde. The overall reactions were monitored by TLC and UV-Visible spectral analysis. All the ligands and metal complexes were isolated from the reaction in the solid form and characterized by IR, UV-Visible, Thermal analysis, Magnetic Susceptibility, Conductivity and some physical measurements. Spectroscopic evidence indicated that the Schiff base was behaved as N, O coordinating chelating agent. Magnetic susceptibility data coupled with electronic spectra suggested that [ZnC15H11N3O3] and [MnC15H11N3O3].2H2O complexes are tetrahedral whereas [NiC15H11N3O3].H2O complex is square planar. The conductivity value indicated that all the complexes were non-electrolyte. Thermal analysis (TGA and DTG) data showed the possible degradation pathway of complexes (C12H8O2, at 200-490 0C and -NH3O-, at 400-650 0C). The Schiff bases and their metal complexes have been shown moderate to strong antimicrobial activity against some pathogenic bacteria.