Vanillin and 2-aminophenol Schiff Base was synthesized in 1:1 mole ratio (HL1). Fe (II) and Ni (II) ions formed complexed with Schiff Base in 1:2. (Fe(HL1)2, Ni(HL1)2) and mixed ligand complexes of 2-aminsophenol with Schiff Base (Fe(HL1) (HL2), Ni(HL1) (HL2)) in 1:1:1 (L-M-L). The complexes were characterized by Solubility, Melting Point, Conductivity, FTIR and UV. The compounds were soluble in Acetone, Methanol, Ethanol, DMSO and DMF with the exception of Fe (II) mixed ligand complex. All the compounds are slightly soluble in chloroform but not soluble in distilled water. The melting points of the metal complexes were at the range of 130oC-190oC. The lower conductivity result ranging from 4.8×10-3-12×10-2 corresponds to non-electrolytic nature of the complexes. In the light of infrared data, the Schiff Base is coordinated to the metal via two O and one N in Fe(HL1)2 and Ni(HL1)2 complexes. In mixed ligand complexes (Fe(HL1) (HL2), Ni(HL1) (HL2)), 2-aminophenol is coordinated to the metal through one O and one N, thus suggesting the six coordinate octahedral geometry for these complexes. The compounds were tested against Staphylococcus aureus, Escherichia coli, Streptococcus pierogis, Klebsiella pneumonia (gram negative bacteria), and Bacillus subtilis, Staphylococcus aureus (gram positive bacteria) using disc diffusion method. The comparative antibacterial studies revealed that, the mixed ligand complexes (Fe(HL1) (HL2), Ni(HL1) (HL2)) were found to be more active against the tested bacterial strains than the free Schiff base and the complexes derived from Schiff base (Fe(HL1)2 Ni(HL1)2).

Keywords: Schiff base; Antibacterial Activity; Metal (II) complexes; Ligands