Triplet-state properties and singlet oxygen generation in a homologous series of functionalized fullerene derivatives

The main properties of the triplet states and the yields of singlet oxygen generation for a series of methano-[60]fullerene adducts with increasing numbers of substituents were determined. The tripler properties investigated are energies, triplet-triplet absorption spectra, extinction coefficients, and quantum yields. A strong correlation is observed between several tripler properties and the topology of the fullerene core. Successive fragmentation of the chromophore of the parent C-60 results in higher triplet energies and lower tripler quantum yields. In addition, singlet oxygen quantum yields (phi(Delta)) were determined for all adducts and decrease as the area of the conjugated fullerene core decreases.