Elucidation of the Key Role of [Ru(bpy)(3)](2+) in Photocatalyzed RAFT Polymerization

作者：Christmann Julien; Ibrahim Ahmad; Charlot Vincent; Croutxe Barghorn Celine; Ley Christian; Allonas Xavier^*

来源：ChemPhysChem, 2016, 17(15): 2309-2314.

DOI：10.1002/cphc.201600034

• computational chemistry
• electron transfer
• energy transfer
• photocatalysis
• RAFT photopolymerization

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.

• 出版日期2016-8-4