Synthesis and characterization of some metal complexes of a Schiff base derived from ninhydrin and α,L-alanine

Abstract

Complexes of Mn(II), Fe(III), Co(II), Ni(II) and Zn(II) with an intermediate Schiff base derived from ninhydrin and α,L-alanine (indane-1,3-dione-2-imine-N-2-propionate, IDIP) were successfully synthesized. All complexes were distinctly colored and were characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared and electronic spectral studies. The ligand (Schiff base) was shown to behave as a monobasic tridentate ONO donor. The Mn(II) and Fe(III) complexes contain only one ligand molecule plus water and chloride(s) per metal ion, while all the others contain two ligand molecules per metal ion. An octahedral geometry is proposed for the metal complexes. A comparative anti-microbial study of the complexes was undertaken against two gram-negative bacteria, Escherichia coli and Proteus mirabilis and one gram-positive bacterium Staphylococcus aureus. It was revealed that most of the complexes and particularly Mn(II), Fe(III) and Co(II) complexes, have a much enhanced activity relative to ninhydrin against Proteus mirabilis and Staphylococcus aureus. All complexes showed a reduced activity against Escherichia coli.