Endohedral metallofullerenes as strong singlet oxygen quenchers

The total quenching rate constants (sum of physical quenching and chemical reaction) of singlet oxygen 1O2 by various fullerenes (C60, C70, C76, C82, La@C82, Ce@C82, Ce2@C80) were determined. The 1O2 quenching capabilities of C82 and endohedral metallofullerenes are found to be comparable to that of β-carotene, a well-known strong 1O2 quencher. This remarkable 1O2 quenching by metallofullerenes is explicable in terms of a combination of energy and charge transfer processes.