fulerenes

Fullerenes are a class of carbon allotropes composed of closed hollow cages of carbon atoms. The best known member is C60, also called buckminsterfullerene or buckyball, a soccer-ball shaped molecule with 60 carbon atoms arranged in a truncated icosahedron.

The cages are highly conjugated and typically formed from sp2-hybridized carbon. C60 has 12 pentagons and 20 hexagons, and Ih symmetry. Other fullerenes such as C70 and larger members differ in shape and size; many can form ions or accommodate atoms inside the cage (endohedral fullerenes).

Fullerenes were discovered in 1985 by Harold Kroto, Richard Smalley, and Robert Curl during experiments vaporizing graphite with a laser in a helium atmosphere. The discovery revolutionized carbon chemistry and earned them the Nobel Prize in Chemistry in 1996.

Production and isolation of fullerenes usually involve laser ablation or electric-arc discharge of graphite in an inert gas, followed by extraction from soot with organic solvents and purification by chromatography.

Fullerenes are stable, conjugated carbon networks with high electron affinity. They can accept electrons to form anions (e.g., C60−) and form various adducts and metal-fullerene complexes. They exhibit interesting photophysical and electrochemical properties and can act as containers for encapsulated atoms or small molecules.

Fullerene-based materials are studied for superconducting fullerides, organic photovoltaics, molecular electronics, catalysis, and drug delivery. Endohedral fullerenes and functionalized derivatives broaden their utility in materials science and nanotechnology.