title: Elucidation of the Key Role of [Ru(bpy)3 ](2+) in Photocatalyzed RAFT Polymerization.
abstract: Photocatalysis reactions using [Ru(II) (bpy)3 ](2+) were studied on the example of visible-light-sensitized reversible addition-fragmentation chain transfer (RAFT) polymerization. Although both photoinduced electron- and energy-transfer mechanisms are able to describe this interaction, no definitive experimental proof has been presented so far. This paper investigates the actual mechanism governing this reaction. A set of RAFT agents was selected, their redox potentials measured by cyclic voltammetry, and relaxed triplet energies calculated by quantum mechanics. Gibbs free-energy values were calculated for both electron- and energy-transfer mechanisms. Quenching rate constants were determined by laser flash photolysis. The results undoubtedly evidence the involvement of a photoinduced energy-transfer reaction. Controlled photopolymerization experiments are discussed in the light of the primary photochemical process and photodissociation ability of RAFT agent triplet states.
authors.affiliation: Laboratory of Macromolecular Photochemistry and Engineering, University of Haute Alsace, 3 bis rue Alfred Werner, 68093, Mulhouse, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Christmann
authors.affiliation: Laboratory of Macromolecular Photochemistry and Engineering, University of Haute Alsace, 3 bis rue Alfred Werner, 68093, Mulhouse, France.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Ibrahim
authors.affiliation: Laboratory of Macromolecular Photochemistry and Engineering, University of Haute Alsace, 3 bis rue Alfred Werner, 68093, Mulhouse, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Charlot
authors.affiliation: Laboratory of Macromolecular Photochemistry and Engineering, University of Haute Alsace, 3 bis rue Alfred Werner, 68093, Mulhouse, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Croutxé-Barghorn
authors.affiliation: Laboratory of Macromolecular Photochemistry and Engineering, University of Haute Alsace, 3 bis rue Alfred Werner, 68093, Mulhouse, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Ley
authors.affiliation: Laboratory of Macromolecular Photochemistry and Engineering, University of Haute Alsace, 3 bis rue Alfred Werner, 68093, Mulhouse, France. xavier.allonas@uha.fr.
authors.forename: Xavier
authors.identifier: http://orcid.org/0000-0003-2194-939X
authors.initials: X
authors.lastname: Allonas
keywords: RAFT photopolymerization; computational chemistry; electron transfer; energy transfer; photocatalysis