Energy transfer in extended thienylene-phenylene-ethynylene dendrimers.

We present a new family of dendrimers with all-conjugated, thienylene (Th) containing photoactive backbones and branched end-groups. Steady-state spectroscopy demonstrates a donor-acceptor system, while picosecond time-resolved fluorescence characterizes a vectorial energy transfer from phenylene-ethynylene (PE) units at the periphery to thienylene-containing PE units at the core. Energy transfer rates of 1.5 and 3.5 ps are observed for generation 2 and 3 dendrimers, indicative of a weakly coupled donor-acceptor system, with couplings on the order of 40-60 cm(-1).