Development of new transition-metal-catalyzed fullerene functionalization

Functional fullerenes have been used widely as excellent n-type semiconductors in solution processable organic electronics, especially as the unique electron acceptors for organic photovoltaics due to their significant increase in solubility while preserving certain electronic and optical properties of pristine fullerenes. Numerous efforts have been made to develop new fullerene functionalization. In comparison with the traditional methods, such as nucleophilic addition of organometallic reagents, cycloaddition, and addition of free radicals, the transition-metal-catalyzed fullerene functionalization has been proved to exhibit high efficiency and selectivity under mild reaction conditions as well as a high compatibility with a wide range of functional groups. We have been interested in the catalytic generation and reactivity of the fullerene radicals. The account describes our recent achievements for the synthesis of various monosubstituted hydrofullerenes, fullerene cycloadducts, single-bonded fullerene dimers, and amine-substituted 1,4-bisadducts in the presence of cobalt and copper catalysts via the formation of the fullerene monoradical as an active species.