Synthesis of Methanofullerenes for Materials Science and Biological Applications

Following the discovery of the macroscopic-scale C₆₀ synthesis by Krätschmer, Huffman and co-workers, the physical properties of this fascinating carbon cage have been intensively investigated [1–8]. Among the most spectacular findings, C₆₀ was found to behave like an electronegative molecule able to reversibly accept up to six electrons, to become a supraconductor in M₃C₆₀ species (M = alkali metals), or to be an interesting material with non-linear optical properties [1–8]. However, this new molecular material aggregates very easily and is insoluble or only sparingly soluble in most solvents. Therefore, pristine C₆₀ is difficult to handle. This serious obstacle for practical applications can be, at least in part, overcome with the help of the organic modification of C₆₀. Effectively, the recent developments in the functionalization of fullerenes allow the preparation of highly soluble C₆₀ derivatives easier to handle, and the electronic properties such as facile multiple reducibility, optical non-linearity or efficient photosensitization that are characteristic of the parent fullerene are maintained for most of the C₆₀ derivatives [1–8].