Synthesis, Characterization and Biocidal Activity of Some Schiff Base Metal(II) Complexes

Abstract

A Schiff base, 2-[4-(N,N-dimethylamino)benzylidene]benzoic acid has been synthesized by the condensation of 4-(N,N-dimethylamino)benzaldehyde and 2-amino-benzoic acid in 1:1 molar stoichiometry. The Schiff base complexes were synthesized from the chloride salts of Fe(II), Cu(II) and Zn(II) in ethanolic medium and elucidated by infrared spectroscopy, CHN elemental analysis, atomic absorption spectroscopy as well as conductivity and magnetic susceptibility measurements. The solubility and thermal stability were also determined. The metal(II) complexes are coloured solids that are soluble in DMF and DMSO. The melting point of the Schiff base was found to be 177 oC, while the complexes decompose within a temperature range of 202–261 oC suggestive of rather good thermal stability. The molar conductance values were low, indicating non-electrolytic nature of the complexes. Elemental analysis revealed that the stoichiometries of the synthesized complexes are of 1:2 metal-to-ligand ratio. All complexes were hydrated. The spectroscopic and magnetic susceptibility data revealed that the complexes possess four- coordinate distorted square planar stereochemistry, whereas the Schiff base behaves as monoanionic bidentate ligand with the nitrogen atom of the azomethine (C=N) and carboxylate oxygen (COO-) as donor sites. The Schiff base and its corresponding metal(II) complexes were assayed against a number of bacterial and fungal strains to evaluate their inhibitory potentials. All the complexes showed significant bactericidal and fungicidal activities against the tested organisms.