Azafullerenes are a class of

heterofullerene Heterofullerenes are classes of fullerenes, at least one carbon atom is replaced by another element. Based on spectroscopy, substitutions have been reported with boron (borafullerenes), nitrogen ( azafullerenes), oxygen, arsenic, germanium, phosp ...

s in which the element substituting for

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

. They can be in the form of a hollow sphere, ellipsoid, tube, and many other shapes. Spherical azafullerenes resemble the balls used in football (soccer). They are also a member of the carbon nitride class of materials that include

beta carbon nitride Beta (, ; uppercase , lowercase , or cursive ; grc, βῆτα, bē̂ta or ell, βήτα, víta) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Modern Greek, it represents the voiced labiod ...

(β-C₃N₄), predicted to be harder than diamond. Besides the pioneering work of a couple of academic groups, this class of compounds has so far garnered little attention from the broader fullerene research community. Many properties and structures are yet to be discovered for the highly-nitrogen substituted subset of molecules. The first

fullerene A fullerene is an allotrope of carbon whose molecule consists of carbon atoms connected by single and double bonds so as to form a closed or partially closed mesh, with fused rings of five to seven atoms. The molecule may be a hollow sphere, ...

molecule to be discovered, and the family's namesake,

buckminsterfullerene Buckminsterfullerene is a type of fullerene with the formula C60. It has a cage-like fused-ring structure (truncated icosahedron) made of twenty hexagons and twelve pentagons, and resembles a soccer ball. Each of its 60 carbon atoms is bonded ...

(C₆₀), was prepared in 1985 by

Richard Smalley Richard Errett Smalley (June 6, 1943 – October 28, 2005) was an American chemist who was the Gene and Norman Hackerman Professor of Chemistry, Physics, and Astronomy at Rice University. In 1996, along with Robert Curl, also a professor of c ...

Robert Curl Robert Floyd Curl Jr. (August 23, 1933 – July 3, 2022) was an American chemist who was Pitzer–Schlumberger Professor of Natural Sciences and Professor of Chemistry at Rice University. He was awarded the Nobel Prize in Chemistry in 1996 for ...

, James Heath, Sean O'Brien, and

Harold Kroto Sir Harold Walter Kroto (born Harold Walter Krotoschiner; 7 October 1939 – 30 April 2016), known as Harry Kroto, was an English chemist. He shared the 1996 Nobel Prize in Chemistry with Robert Curl and Richard Smalley for their discovery o ...

Rice University William Marsh Rice University (Rice University) is a Private university, private research university in Houston, Houston, Texas. It is on a 300-acre campus near the Houston Museum District and adjacent to the Texas Medical Center. Rice is ranke ...

. A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, tube, and many other shapes. Spherical fullerenes are also called buckyballs, and they resemble the balls used in football (soccer). Fullerenes are similar in structure to graphite, which is composed of stacked graphene sheets of linked hexagonal rings; but they may also contain pentagonal (or sometimes heptagonal) rings. Azafullerenes were first discovered in 1993 and reported in the California State Science Fair. The derivatives were formed in the gap between two graphite rods connected to an electric power supply. A small air leak led to contamination of the inert atmosphere and the subsequent reaction. The materials can also be formed by chemical reactions on

or laser ablation of graphitic materials. Subsequent work revealed a wide range of carbon nitride structures. Examples include (C₅₉N)₂ (biazafullerenyl),C₅₈N₂ (diaza 0ullerene), C₅₇N₃ (triaza 0ullerene) and C₄₈N₁₂. The nitrogen atoms substitute for carbon atoms on the cage-like molecules. Much of the work has been theoretical in nature. The C₄₈N₁₂ molecule was calculated to be an insulator, with the eight all-carbon rings forming regions of extended electron delocalization.

References

{{Reflist Fullerenes