Distance-independent photoinduced energy transfer over 1.1 to 2.3 nm in ruthenium trisbipyridine-fullerene assemblies

Ruthenium trisbipyridine C-60 dyads linked via para-phenyleneethynylene units have been prepared. They displayed a rapid energy transfer from Ru to C-60 with a rate that was independent of distance, from 1.1 to 2.3 nm. The results are explained by a hopping mechanism involving a bridge-localized excited-state. In fact, for the longest bridge this state was lower in energy than the Ru-based MLCT state, as evidenced by the spectroscopic data.