Donor-acceptor polymers: A conjugated oligo(p-phenylene vinylene) main chain with dangling perylene bisimides

Two new donor-acceptor copolymers that consist of an enantiomerically pure oligo(p-phenylene vinylene) main chain with dangling perylene bisimides have been synthesized by using a Suzuki cross-coupling polymn. Absorption and CD spectroscopy revealed that the transition dipole moments of the donor in the main chain and the dangling acceptor moieties of the copolymers are coupled and in a helical orientation in soln., even at elevated temps. A strong fluorescence quenching of both chromophores indicates an efficient photoinduced charge transfer after photoexcitation of either donor or acceptor. The formation and recombination kinetics of the charge-sepd. state were investigated in detail with femtosecond and near-steady-state photoinduced absorption spectroscopy. The charge-sepd. state forms within 1 ps after excitation, and recombination occurs with a time const. of 45-60 ps, both in soln. and in the solid state. These optical characteristics indicate a short distance and appreciable interaction between the electron-rich donor chain and the dangling electron-poor acceptor chromophores