C

Buckminsterfullerene

Before the reported synthesis of buckminsterfullerene, the known allotropic forms of carbon were two crystalline forms (diamond and graphite) and the amorphous forms, charcoal, carbon, and coke, all of which had been known since antiquity.

In 1985, this soccer ball-like cluster of 60 carbon atoms was discovered upon laser vaporization of a graphite surface; the discoverers, H.W. Kroto, R.F. Curl, and R.E. Smalley, were awarded the Nobel Prize in Chemistry in 1996. The C60 compound was named buckminsterfullerene (after R. Buckminster Fuller, the engineer whose geodesic domes had the same symmetry) and is most popularly known as “bucky balls”. An entire class of carbon structures arranged in hollow structures is known as fullerenes, which are often classified as as higher- or lower order fullerenes based on whether N is greater or lesser than 60, i.e., buckminsterfullerene, C60. Among them are C70, C76, C82, C84, and C36 fullerenes.

Although they have both a uniform composition and a molecular symmetry, fullerenes cannot be classified as minerals or crystals because larger symmetrical structures cannot be constructed from these basic materials by a simple translation along three axes.