Synthesis and photophysical properties of a [60]fullerene compound with dimethylaniline and ferrocene connected through a pyrazolino group: A study by laser flash photolysis

Pyrazolino[60]fullerene covalently-linked to ferrocene and N,N-dimethylaniline groups has been prepared and studied using time-resolved spectroscopic methods. The fluorescence quenching of the C₆₀ moiety indicates that charge-separation takes place via the singlet excited state of the C₆₀ moiety in both polar and non-polar solvents. The charge-separated state, in which an electron is localized on the C₆₀ sphere and a hole is located on the whole donor moieties of ferrocene, pyrazole, and N,N-dimethylaniline groups, has been confirmed by nanosecond transient spectra in the visible and near-IR spectral region. The lifetimes of the radical ion-pairs are as long as 30-50 ns in both polar and non-polar solvents.