Multiphoton, Multielectron Transfer Photochemistry in a Soluble Polymer

The effects of laser irradiance and quencher concentration on photochemical electron transfer in a RuII-bpy derivatized, polystyrene polymer have been studied. The polymer was a 1:1 copolymer of styrene:p-chloromethylstyrene with, on the average, ∼30 repeat units in which each of the chloro groups was replaced by a [RuII(bpy)2(4-CH2O-4‘-CH3bpy)]2+ chromophore by nucleophilic substitution. The abbreviation for the resulting polymer salt is [co-PS-CH2OCH2-(RuII 30)](PF6)60. Upon visible excitation by laser flash photolysis at high irradiances, multiphoton excitation in the presence of high concentrations of the reductive quencher phenothiazine leads to individual polymeric strands that are reduced, on the average, by up to seven electrons to give PS-CH2OCH2-(Ru2+ 23Ru+ 7)]53+.