Alternating copolymers based on perylene bisimide and oligo(p-phenylene ethynylene) units: Synthesis, characterization, and photoinduced energy and electron transfer processes of a new class of donor-acceptor systems

A Hagihara-Sonogashira cross-coupling reaction has been used to synthesize a new copolymer consisting of electron-accepting perylene bisimide (PBI) and electron-donating oligo(p-phenylene ethynylene) (OPE) units. Photoinduced singlet energy transfer and charge separation have been studied in solution via steady-state absorption, excitation, fluorescence, and theoretical calculations. The electron transfer from the OPE excited state competes with a singlet energy transfer state to the PBI unit. The results show that the excitation of the OPE unit in the polymer results in energy and electron transfers, while the excitation of the PBI unit in the polymer only result in electron transfer.