Photon harvesting polymers: intracoil energy transfer in anthryl- and fluorescein-tagged polystyrene

Abstract

Polystyrene containing small mole fractions of pendent 9,10-diphenylanthracene (DPA) and fluorescein (F) was prepared. Absorption of light by DPA results in very efficient intracoil sensitization of the 1F* state. The quantum efficiency (χ) of this process has been estimated as 0.75 in dimethylformamide (DMF) and 0.95 in 5:1 DMF/H2O. The increase in χ in this latter solvent mixture is ascribed to the diminished polymer coil size in this poorer solvent. Analysis of the time dependence of fuorescence suggests a combined static and dynamic quenching of 1(DPA)* by energy transfer. Studies of 1(DPA)* and 1(F)* fluorescence quenching by DABCO corroborate this model.