A Novel Ni(II) Complex: Synthesis, Spectral and Biological Activity Determination Studies

Abstract

A new Ni(II) metal complex of the ligand ((E) methyl 6-benzyl-2-(4- (benzoxy)benzylideneamino)-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate), derived from (methyl 2-amino-6-benzyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate) and 4- benzoxybenzaldehyde, has been obtained. Standard spectroscopic techniques were used to elucidate the structural features of the ligand and its nickel (II) complex (elemental analysis, Fourier transform infrared (FT-IR) spectra, 1H-NMR (proton nuclear magnetic resonance), elemental analysis, molar conductance, UV–Vis ( ultraviolet-visible) spectra, magnetic susceptibility, LC-Mass spectrometry, and TGA (thermogravimetric analysis). The analytical data showed that the Ni(II) complex is located in the ligand: metal ratio (1:1). Spectral studies revealed that the ligand bonds bidentate to the Ni metal ion via the nitrogen atom of the CH=N (azomethine) group and the oxygen atom of the C=O (carbonyl) group. A distorted octahedral structure can be suggested for the Ni(II) complex from electronic spectrum data and magnetic susceptibility values. The in vitro antioxidant and enzyme inhibition activities of Ni(II) complex were investigated. Acetylcholineesterase enzyme inhibition potential of the synthesized Ni(II) complex was found to be close to the standard tacrine compound. The Ni(II) complex was evaluated for its in vitro antioxidant activity according to the DPPH (1,1-Diphenyl-2-picrylhydrazyl) free radical scavenging activity and CUPRAC (cupric ions reducing capacity) in vitro bioanalytical methods. The synthesized Ni(II) complex showed effective antioxidant activity according to the both CUPRAC and DPPH method.