title: Characterization and catechole oxidase activity of a family of copper complexes coordinated by tripodal pyrazole-based ligands.
abstract: A family of tripodal pyrazole-based ligands has been synthesized by a condensation reaction between 1-hydroxypyrazoles and aminoalcohols. The diversity was introduced both on the substituents of the pyrazole ring and on the side chain. The corresponding copper(II) complexes have been prepared by reaction with CuCl(2) in tetrahydrofuran. They have been characterized by EPR, UV spectroscopy and cyclic voltammetry. The absence of the half-field splitting signals in EPR suggests that the complex exists in solution as mononuclear species. The influence of substituents and side chain of the tripodal ligand on the catecholase activity of the complexes was studied. The reaction rate depends on two factors. First, the presence of an oxygen atom in the third position of the side chain should be avoided to keep the effectiveness of the reaction. Second, the electronic and steric effects of substituents on the pyrazole ring strongly affect the catalytic activity of the complex. Thus, best results were obtained with complexes containing unsubstituted pyrazole based-ligands. Kinetic investigations with the best catalyst based on the Michaelis-Menten model show that the catalytic activity of the mononuclear complex is close to that of some dicopper complexes described in literature.
authors.affiliation: Université de Rennes 1, UMR-CNRS 6226, Laboratoire des Sciences Chimiques de Rennes, Equipe Matière Condensée et Systèmes Electroactifs, Campus de Beaulieu, 35042 Rennes cedex, France.
authors.forename: R
authors.initials: R
authors.lastname: Marion
authors.forename: M
authors.initials: M
authors.lastname: Zaarour
authors.forename: N A
authors.initials: NA
authors.lastname: Qachachi
authors.forename: N M
authors.initials: NM
authors.lastname: Saleh
authors.forename: F
authors.initials: F
authors.lastname: Justaud
authors.forename: D
authors.initials: D
authors.lastname: Floner
authors.forename: O
authors.initials: O
authors.lastname: Lavastre
authors.forename: F
authors.initials: F
authors.lastname: Geneste
mesh_terms: D032701:Biomimetics; D002384:Catalysis; D002396:Catechols / Q000737:chemistry*; D002614:Chelating Agents; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D006861:Hydrogen Peroxide / Q000737:chemistry; D007700:Kinetics; D010084:Oxidation-Reduction; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002396:Catechols; D002614:Chelating Agents; D056831:Coordination Complexes; D011720:Pyrazoles; D003300:Copper; D006861:Hydrogen Peroxide