Catechol oxidase and Copper(I/II) Complexes Derived from Bipyrazol Ligand: Synthesis, Molecular Structure Investigation of New Biomimetic Functional Model and Mechanistic Study

Abstract Herein, we investigate the in situ copper(I/II) complexes of pyrazole based on ligand: 5,5'-diphenyl-1H,1'H-3,3'-bipyrazole ( H 2 L ) and Its corresponding [C 36 H 28 CuN 8 ] ( CuL ). Copper(I/II) complexes were tested for their reactivity towards the oxidation of catechol to o-quinine with the atmospheric dioxygen by following the appearance of quinone spectrophotometrically at ambient conditions in order to demonstrate the structural parameters essential to the reactivity of the enzyme and to understand the mechanism of action. The reaction rate depends on three parameters: the nature of counter anion, the nature of solvent and the concentration of ligand. We compared the potentialities of the complexes formed in situ as well as the synthesized complex, as a catalyst of the oxidation reaction of catechol to o-quinone.The highest rate activity given by the complex resulting from two equivalents of ligand H 2 L and one equivalent of [Cu(NO 3 ) 2 ] in MeOH is to 3.10 µmol.L -1 .min -1 .