title: Characterization of Cu(II)-ACC complexes and conversion of the bound ACC into ethylene in the presence of hydrogen peroxide. detection of a brown intermediate at low temperature.
abstract: Two copper(II)-ACC complexes were prepared and characterized: [Cu(bpy)(ACC)(H(2)O)]CO(4) (1) and [Cu(ACC)(2)](3).4H(2)O (2). Their crystallographic structures are described and analyzed. Spectroscopic characterizations (UV-visible and EPR) confirm that the structure is maintained in solution. These complexes are able to produce ethylene in the presence of hydrogen peroxide in an "ACC Oxidase-like" reaction in water and in methanol. The conversion of ACC into ethylene depends on the amount of base, and, in methanol, 3 equivalents of NaOH are needed for optimum activity. The base is proposed to play a role in H(2)O(2) deprotonation. The presence of an exogenic ligand (bpy) is important for the reactivity and may stabilize a reaction intermediate. Indeed, a brown intermediate with an absorption band centered at 433 nm can be detected at low temperature when 1 is treated with 10 equivalents of H(2)O(2).
authors.affiliation: BiosCiences FRE CNRS 3005, Faculté des Sciences et Techniques, Université Paul Cézanne Aix-Marseille III, avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France.
authors.forename: Wadih
authors.initials: W
authors.lastname: Ghattas
authors.forename: Michel
authors.initials: M
authors.lastname: Giorgi
authors.forename: Christian
authors.initials: C
authors.lastname: Gaudin
authors.forename: Antal
authors.initials: A
authors.lastname: Rockenbauer
authors.forename: Marius
authors.initials: M
authors.lastname: Réglier
authors.forename: A Jalila
authors.initials: AJ
authors.lastname: Simaan