Fullerenes are highly symmetrical spherical molecules consisting of carbon atoms, in which the carbon atoms are arranged exclusively in pentagons and hexagons. The best known and, at the same time, most stable of the fullerenes is buckminsterfullerene (C60), with an icosahedral structure, that was used as a model for footballs for a long time. The higher homologues C70, C76, C80, C82, C84, C86, C90 and C94 are also widespread. Their diameter is in the range of slightly more than 1 nm.
Fullerenes are produced through arc evaporation of graphite, using resistance heating, or using a laser in an inert atmosphere. The fullerenes are best separated from the simultaneously produced amorphous carbon black using aromatic solvents such as benzene or toluene, in which they exhibit good solubility and produce a characteristic deep-violet colour. Separation into the various fullerenes is then performed by chromatography.
Although fullerenes were discovered in 1985 by Kroto and Smalley, and despite the numerous research and development projects that have since been carried out, there are to this day only a few commercial applications. Intensive investigation was performed into the possibility of storing other gases inside the cage-like, hollow fullerenes; hydrogen was particularly of interest here, in order to establish a safe hydrogen storage system. Due to the high associated costs and the limited storage capacity, however, this application was never implemented. Currently, intensive investigations are being carried out into an application in cancer therapy, as well as their use as a lubricant or a catalyst.