Ultrafast Energy Transfer in a Regioregular Silylene-Spaced Copolymer
The energy-transfer properties of a regioregular silylene-spaced alternating donor−acceptor copolymer (donor−SiMe2−acceptor−SiMe2)m are determined with time-resolved spectroscopy; 4,4′-divinylbiphenyl serves as donor and 4,4′-divinylstilbene as acceptor. Steady-state fluorescence spectra show that the energy transfer is efficient. With excitation at 266 nm, fluorescence up-conversion curves at various detection wavelengths are measured to explore the detailed dynamics of the energy transfer. A rate ∼(0.3 ps)−1 for energy transfer between the S1 states of the donor and acceptor moieties is observed. Theoretical calculations based on fragment excitation difference provide a rate of energy transfer near the experimental value with detailed insight into the mechanism of energy transfer. The results of theoretical calculations indicate that the Coulomb interaction is dominant and the Dexter process is weak. The high-multipole interactions are important for energy transfer.