FULLERENE

The structure of buckminsterfullerene (C60). any of a class of closed, hollow, aromatic carbon compounds that are made up of 12 pentagonal and differing numbers of hexagonal faces. Fullerenes consist of even numbers of carbon atoms, with a range of from 32 to as many as 600 atoms. Fullerenes are the third form of pure carbon known to exist, after the network solids of diamond and graphite. The first fullerene was discovered in 1985 by Richard E. Smalley and Robert F. Curl, Jr., of the United States and Sir Harold W. Kroto of the United Kingdom. These chemists used a laser to vaporize graphite rods in an atmosphere of helium gas. The fullerene thus obtained is composed of 60 carbon atoms (C60) joined together by single or double bonds to form a hollow sphere with 12 pentagonal and 20 hexagonal faces, a design that resembles a soccer ball. Fullerenes derive their name from the American architect R. Buckminster Fuller, whose geodesic dome design is similar to the molecular structure of C60. Buckminsterfullerene, or buckyball, is the name applied to C60 itself. The physical and chemical properties of C60 and other fullerenes are now under investigation. C60 is an extremely stable compound; every carbon vertex (at the junction of one pentagon and two hexagons) is identical, resulting in an equal distribution of bonding strains. The molecule can withstand very high temperatures and pressures. The outer surface of C60 can react with a wide variety of atoms and molecules, yet its stable, spherical structure is maintained. After having entered a break in C60's surface carbon bonds under high temperatures, certain atoms (such as helium) can become trapped within the host molecule. Because these captive atoms cannot react with their host, a new kind of chemical formula had to be devised to denote such a compound; the formula He@C, for example, designates C60 with a helium atom trapped inside of it. The unique structure and properties of buckminsterfullerene suggest potential uses for fullerenes as superconductors, lubricants, industrial catalysts, and drug-delivery systems (e.g., targeted cancer therapy).