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, ellipsoid, tube, or many other shapes and sizes. Graphene (isolated atomic layers of graphite), which is a flat mesh of regular hexagonal rings, can be seen as an extreme member of the family.
Fullerenes with a closed mesh topology are informally denoted by their empirical formula C(n), often written C(n), where n is the number of carbon atoms. However, for some values of n there maybe more than one isomer.

The family is named after buckminsterfullerene (carbon C60 or fullerene C60), the most famous member, which in turn is named after Buckminster Fuller. The closed fullerenes, especially carbon 60, are also informally called buckyballs for their resemblance to the standard ball of association football ("soccer"). Nested closed fullerenes have been named bucky onions. Cylindrical fullerenes are also called carbon nanotubes or buckytubes. The bulk solid form of pure or mixed fullerenes is called fullerite.

Fullerenes had been predicted for some time, but only after their accidental synthesis in 1985 were they detected in nature and outer space. The discovery of fullerenes greatly expanded the number of known allotropes of carbon, which had previously been limited to graphite, diamond, and amorphous carbon such as soot and charcoal. They have been the subject of intense research, both for their chemistry and for their technological applications, especially in materials science, electronics, and nanotechnology.

Carbon nanostructures
Conditionally, all carbon nanostructures can be divided into fullerenes and fulleroid structures.
Fullerenes, which are also called footballens, backyball, are a chemically stable closed surface structure of carbon, in which carbon atoms are located at the vertices of regular hexagons or pentagons, regularly covering the surface of a sphere, and the pentagons are isolated from each other, i.e. they do not have common contact points either on the edges or in the vertices. The number of carbon atoms in a fullerene molecule is greater than or equal to 60.

Chemists divide fullerenes into two groups:
- light fullerenes - which include carbon C60 and carbon C70
- and heavy (higher) fullerenes - which include the rest of the fullerenes, the number of atoms in which more than 70.

"Fullerenes" with the number of carbon atoms less than 60 belong to the so - called non-fullerenes, which can have both closed and open structures. In closed structures that look like fullerenes, due to the small number of carbon atoms, there are quite strong stresses between the carbon atoms, which significantly weaken the interatomic interactions in the molecule. Open structures are associated with the shape of broken egg shells. Due to their structural features, not all fullerenes are unstable to external influences.

Fullerene is able to interact with different substances with the formation of stable structures. In this regard, its derivatives are also promising for use in various fields of science and technology. There are endohedral and exohedral derivatives (or complexes). In the first, already synthesized in macro quantities, one or more metal atoms, nonmetals, or even individual molecules are placed inside the carbon sphere. When the latter are formed, the interaction occurs on the outer surface of the fullerene.

From the variety of fulleroid structures – nanotubes, nanoarray (nanobarelle), monoplanar, neolocality and other, currently the greatest interest is carbon nanotubes.

Nanotubes are cylindrical macromolecules consisting of a folded graphite plane consisting of hexagons. As a rule, the ends of nanotubes are closed with so-called "fullerene caps". The diameter of nanotubes does not exceed several nanometers, and the length can be from one to several microns.