Synthesis, characterization, antibacterial, DNA cleavage and SOD activities of some 3d metal complexes of ethyl[2-(1H-indol-3-yl)methyleneamino]-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate

Abstract

A series of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized using a novel Schiff base ligand derived from indole-3-carboxaldehyde and 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene. The ligand and the metal complexes have been characterized on the basis of various physico-chemical and spectral studies. The analytical, spectral data (Infrared, UV–Vis, 1H NMR, 13C NMR, ESR, FAB mass) and magnetic susceptibility measurements indicate that the ligand is coordinated to the metal ion through azomethine nitrogen and oxygen of the ester carbonyl group. The ligand and the metal complexes have been screened for their antibacterial activities against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa. The results indicate that the metal complexes are more potent bactericides than the ligand. DNA cleavage activity of the ligand and the metal complexes has been examined by agarose gel electrophoresis technique. The copper(II) complex shows increased nuclease activity when compared to the ligand and the metal complexes. Superoxide dismutase (SOD) mimetic activity of the ligand and complexes has also been assessed for their ability to inhibit the reduction of nitrobluetetrazolium chloride (NBT), and it is observed that they possess promising SOD mimetic activity.