Observation of Intramolecular Interaction in Fluorescent Star-Shaped Polymers: Evidence for Energy Hopping between Branch Chains.

Time-resolved fluorescence anisotropy measurements were performed on three-branched star-shaped polymers, based on precisely synthesized poly(9,9-di-n-octyl-fluorene vinylene)s containing C6F5 end groups. The star-shaped polymers showed identical fluorescence spectra, fluorescence lifetimes, and quantum yields to those of the reference single-chain oligomer. However, a rapid fluorescence anisotropy decay was observed in two kinds of star-shaped polymers, while such decay was not seen in the corresponding single-chain oligomer. On the basis of the analysis using an incoherent hopping model, the observed rapid anisotropy decay is attributable to energy hopping processes between branches within a single polymer species, and its rate was deduced to be ca.100 ps depending upon the core part.