Synthesis and Photoinduced Energy‐ and Electron‐Transfer Processes of C60–Oligothienylenevinylene–C70 Dumbbell Compounds

Unsymmetric dumbbell molecules based on N-methylpyrrolidine[60]fullerene, oligothienylenevinylenes (nTV; n=2, 4), and N-methylpyrrolidine[70]fullerene, namely, C60-nTV-C70 were synthesized and their photophysical properties were studied. In nonpolar solvents, photoinduced energy-transfer process predominantly takes place from the singlet excited state of nTV to C60 and C70, as was confirmed by time-resolved emission and transient absorption spectroscopy. In polar solvent, charge-separation processes take place instead of energy transfer. The generated charge-separated radical-ion pairs decay to the neutral molecules by a fast charge-recombination process; for n=4, a rate constant of 2×107 s−1 and lifetime of 50 ns were evaluated.