Light-driven charge separation in isoxazolidine-perylene bisimide dyads.

A series of arrays for light-driven charge separation is presented, in which perylene tetracarboxylic bisimide is the light-absorbing chromophore and electron acceptor, whereas isoxazolidines are colourless electron donors, the electron-releasing properties of which are increased with respect to the amino group by means of the alpha-effect. Charge separation (CS) in toluene over a distance ranging from approximately 10 to approximately 16 A, with efficiencies of approximately 95 to approximately 50 % and CS lifetimes from 300 ps to 15 ns, are demonstrated. In dichloromethane the charge recombination reaction is faster than charge separation, preventing accumulation of the CS state. The effects of solvent polarity and molecular structure are discussed in the frame of current theories.