Synthesis and photoinduced intramolecular processes of fulleropyrrolidine-oligothienylenevinylene-ferrocene triads

Two new triads based on N-methylfulleropyrolidine, oligothienylenevinylenes (nTV) and ferrocene (Fc), namely C-60-nTV-Fc (n=2, 4) have been synthesized. A HOMO-LUMO gap as low as 1.09-1.11 eV was experimentally determined by cyclic voltammetry. In both polar and nonpolar solvents, photoinduced charge-separation (CS) processes in C-60-nTV-Fc predominantly take place from the singlet excited states Of C-60 and nTV; this result was indicated by steady and time-resolved emission spectroscopy. In the case Of C-60-4TV-Fc, the CS state was indicated by the nanosecond transient absorption spectra. In C-60-2TV-Fc, although the CS process was also confirmed by the fluorescence quenching in nonpolar and polar solvents, the lifetimes of the CS states were shorter than those Of C-60-4TV-Fc. It was revealed that the introduction of Fc donor moiety at the end of the longer nTV chain in the C-60-nTV dyad systems effectively increases the CS efficiency and the lifetimes of CS states.