Antibacterial Activity of Co(II), Ni(II) and Cu(II) complexes with asymmetrical Schiff base ligand

Abstract

In this study, biologically active mononuclear complexes of Cu (II), Ni (II) and Co (II) were prepared with a asymmetric Schiff base ligand (H.L).The synthesis process for asymmetric Schiff base ligand is simple and consists of the following steps: (1) condensation of 1-benzoylacetone (1-phenyl-1,3-butanedione) and 1,3-diaminopropane in 1:1 molar ration yielded the half unit compound (H.U). (2) Preparing the new asymmetric Schiff base ligand (H.L) by treating the (H.U) compound with 2-hydroxy-5-nitrobenzaldehyde. The structure of the ligand was elucidated by analytical and spectroscopic analysis. The structure of asymmetric Schiff base ligand and metal complexes were characterized by various techniques such as elemental analysis, IR, 1 H-NMR, UV-vis, conductivity and magnetic moment measurements. Square-planar and octahedral geometries are suggested for the Cu (II), Co (II) and Ni (II) complexes. These compounds were screened for in vitro antibacterial activity against Gram positive bacteria (Staphylococcus aureus, Bacilus subtilis) and Gram negative bacteria (Escherichia coli, Shigella sonnei and Pseudomonas arioginosa). The Cu (II) and Ni (II) complexes had broad-spectrum activity in the inhibitory zones range of 14-25 and 15-28 mm, respectively. All the new complexes have higher activity than the free ligand.