As part of the remarkable progress made in this eld, it has been demonstrated in the last years that the behavior and processing of the C60 fullerene can be strongly modi ed via the chemical functionalization of its surface, i.e., by covalently attaching several types of atoms, molecules, or molecular groups (Coheur et al., 2000; Fanti et al., 2002; Sitharaman et al., 2004). e previous nding has led to the fabrication of a large number of organic derivatives, and has signi cantly expanded the scope of the science of these kinds of carbon clusters. In particular, several types of functionalized C60 molecules have been recently synthesized for their possible use in new electronic and optical devices, as well as for developing possible applications in biology and medicine. For example, the use of functionalized fullerenes as photoactive molecular systems has recently been discussed, assuming particular importance due to the conversion of solar energy into electric current (Rincón et al., 2003). In addition, water-soluble C60 derivatives have been proposed

as HIV protease inhibitors (Friedman et al., 1993) and to promote interactions with target molecules (Friedman et al., 1993; Schinazi et al., 1993; Tokuyama et al., 1993), such as a particular protein on a cell surface. ey have also been de ned as potent antioxidants (Dugan et al., 1997) and as neuroprotectants in vivo (Krusic et al., 1991) and, nally, if metal atoms belonging to the lanthanoid group can be trapped in the inside of the carbon cage, as good candidates for a new generation of novel magnetic resonance imaging (MRI) contrast agents (Mikawa et al., 2001).