Antioxidant, antibacterial and electrochemical activity of (E)-N-(4 (dimethylamino) benzylidene)-4H-1,2,4-triazol-4-amine ligand and its transition metal complexes

Transition metal complexes of Ni(II) (1), Co(II) (2) and Cu(II) (3) supported by a Schiff base ligand, namely (E)N-(4 (dimethylamino)benzylidene)-4H-1,2,4-triazol-4-amine (L) have been synthesized. The ligand has been characterized by various spectral studies (H-1 NMR, C-13 NMR, FTIR, UV -Vis and ESI-MS). The metal complexes have been characterized by FTIR, UV -Vis, ESI-MS and elemental analysis.. Elemental analysis and ESI-MS studies confirmed that metal complexes form at 1:2 (metal:ligand) ratio. The electrochemical behaviors of the metal complexes in acetonitrile have also been studied using cyclic voltammetry and metal complexes have showed by reducing in their metal center. In vitro stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay was used to estimate the antioxidant activity of ligands and its metal complexes. Complex 3 exhibited most potent scavenging property with IC50 value 1.97 +/- 0.08 mu g/mL among the tested compounds compared to the standard antioxidant ascorbic acid (IC50 value 1.14 +/- 0.17 mu g/mL). Antibacterial screening investigated by disc diffusion method against gram positive (Staphylococcus aureus, Bacillus subtilis and Staphylococcus epidermidis) and gram negative (Escherichia coli) bacterial strains. The result has exhibited that the complex 2 had prominent inhibitory property against gram positive bacterial strains at the dose of 250 mu g/mL and 500 mu g/mL. Moreover, the complex 3 have also showed good antibacterial activity against Staphylococcus aureus and Bacillus subtilis at the dose of 500 mu g/mL.