What Is a Fullerene?

Fullerenes are the third allotrope of carbon (after diamond and graphite), consisting of carbon atoms bonded in pentagons and hexagons to form closed cage structures. The most stable and famous is C60: 60 carbon atoms arranged in 12 pentagons and 20 hexagons, identical in geometry to a soccer ball. It was discovered in 1985 by Harold Kroto, Robert Curl, and Richard Smalley during laser ablation experiments on graphite, earning them the 1996 Nobel Prize in Chemistry. Named after architect Buckminster Fuller (whose geodesic domes share the geometry), fullerenes have unique properties: they are extremely strong for their weight, can trap atoms inside their cages (endohedral fullerenes), and exhibit interesting electronic, optical, and superconducting properties. Carbon nanotubes (discovered 1991) are essentially elongated fullerenes and are among the strongest materials known. Fullerenes have been found in geological deposits, meteorites, and even in space around dying stars.