Synthesis, characterization of thiosemicarb?zone metal complexes and their antioxidant activity in different in vitro model systems

Abstract

The synthesis of bimetallic Cu(II), Co(II), Ni(II), Zn(II) and U(VI) complexes with general stoichiometry [H2L M(X2)(H 2O)2] (where H2L is the di-deprotanated ligand and X is chloride/sulphate) were obtained with the ligand terephthaladehyde bis(thiosemicarbazone) (H2L) and are discussed. The ligand and its binuclear complexes were characterized by micro analysis (CHNS), 1H-NMR, FT-IR, UV-vis, TG-DTA and conductance measurements. The thermal behaviour of these complexes showed that the hydrated complexes loose water molecules of hydration in the first step, followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The molar conductance measurements of the complexes in DMF correspond to the non-electrolytic nature of the complexes. Furthermore, the antioxidant activity of the ligand and its complexes were determined in vitro by the hydroxyl radical scavenging, DPPH, NO and reducing power methods. The obtained IC50 value of the DPPH activity for complex 2 (IC50 = 0.254 M) was shown to be the best.