title: Pyridine as proton acceptor in the concerted proton electron transfer oxidation of phenol.
abstract: Taking pyridine as a prototypal example of biologically important nitrogen bases involved in proton-coupled electron transfers, it is shown with the example of the photochemically triggered oxidation of phenol by Ru(III)(bpy)(3) that this proton acceptor partakes in a concerted pathway whose kinetic characteristics can be extracted from the overall kinetic response. The treatment of these data, implemented by the results of a parallel study carried out in heavy water, allowed the determination of the intrinsic kinetic characteristics of this proton acceptor. Comparison of the reorganization energies and of the pre-exponential factors previously derived for hydrogen phosphate and water (in water) as proton acceptors suggests that, in the case of pyridine, the proton charge is delocalized over a primary shell of water molecules firmly bound to the pyridinium cation.
authors.affiliation: Laboratoire d'Electrochimie Moléculaire, UMR CNRS 7591, Université Paris Diderot, Bât. Lavoisier, 15 rue Jean-Antoine de Baif, 75205 Paris Cedex 13, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Bonin
authors.forename: Cyrille
authors.initials: C
authors.lastname: Costentin
authors.forename: Marc
authors.initials: M
authors.lastname: Robert
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Savéant
mesh_terms: D004579:Electron Transport; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D011522:Protons; D011725:Pyridines / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D010636:Phenols; D011522:Protons; D011725:Pyridines; C023666:pyridine