FULLERENE

any of a class of carbon molecules in which the carbon atoms are arranged into 12 pentagonal faces and 2 or more hexagonal faces to form a hollow sphere, cylinder, or similar figure. The smallest possible fullerene molecule may have as few as 32 atoms of carbon, although fullerenelike molecules (lacking a hexagonal face) with as few as 20 carbon atoms have been found.

The most common and most stable fullerene is buckminsterfullerene, a spheroidal molecule, resembling a soccer ball, consisting of 60 carbon atoms. Buckminsterfullerene is the most abundant cluster of carbon atoms found in carbon soot. It is also the smallest carbon molecule whose pentagonal faces are isolated from each other. Other fullerenes that have been produced in macroscopic amounts have 70, 76, 84, 90, and 96 carbon atoms, and much larger fullerenes have been found, such as those that contain 180, 190, 240, and 540 carbon atoms.

Fullerenes were first identified in 1985 as products of experiments in which graphite was vaporized using a laser, work for which R. F. Curl, Jr., R. E. Smally, and H. W. Kroto shared the 1996 Nobel Prize in Chemistry. Fullerenes have since been discovered in nature as a result of lightning strikes, in the residue produced by carbon arc lamps, in interstellar dust, and in meteorites.

Fullerene chemistry involves substituting metal atoms for one or more carbon atoms in the molecule to produce compounds called fullerides. Among these are conducting films of alkali metal-doped fullerenes and superconductors (potassium-doped T_c 18 degrees Kelvin, rubidium-doped T_c 30 degrees Kelvin). Fullerenes also have been used to produce tiny diamonds and thin diamond films. Fullerene research is expected to lead to new materials, lubricants, coatings, catalysts, electro-optical devices, and medical applications.

See M. S. Dresselhaus et al., Science of Fullerenes and Carbon Nanotubes (1996); H. W. Kroto, The Fullerenes: New Horizons for the Chemistry, Physics, and Astrophysics of Carbon (1997); R. Taylor, ed., Lecture Notes on Fullerene Chemistry (1999).

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