Synthesis, characterization, electrochemical behavior and antioxidant activity of new copper(II) coordination compounds with curcumin derivatives

Abstract

Five new copper(II) coordination compounds were prepared by template synthesis, using curcumin, 2-hydrazinobenzothiazole and metal salt (copper chloride, bromide, acetate and nitrate) in 1:2:1 and 1:2:2 molar ratio. The complexes were characterized by elemental and thermogravimetric analysis, IR, UV–Vis and mass spectroscopic methods and cyclic voltammetric studies. On the basis of physico-chemical measurements the following formulae have been assigned to the complexes: [Cu(H2L)(H2O)2]Cl2·H2O, [CuL]·H2O, [Cu(H2L)(H2O)Br]Br·5H2O, [Cu2L(H2O)4](NO3)2·2H2O and [Cu2(H2L)(NO3)4]·H2O, where H2L is the hydrazone ligand formed in the reaction conditions. Metal complexes were tested for antioxidant activity by photochemiluminescence and this activity was quantified by comparison with TROLOX®, as standard. The results show that all complexes are more potent antioxidant agents than curcumin. Keywords: Curcumin, Cu(II)-curcumin derivative complexes, Antioxidant, Free radicals