Rotaxane

Rotaxanes (Latin rota, wheel; axis, axis) are substances that are composed of at least one molecule with a linear unit, on which at least one macrocycle ( a cyclic molecule with a ring that is large enough to be threaded onto the linear molecule to be ) is threaded. The macrocycle is held in a certain way by non-covalent interactions on its position in the molecule. The existence of rotaxanes was proved in 1967.

The macrocycle is, for example, thereby held in its position, that the molecule having end groups that prevent the broken threaded macrocycle leaves its position on the linear molecule, since they are too large, or by the fact that the molecule and the macrocycle interaction. stand The cohesion of the rotaxanes is not based on the formation of covalent bonds. There appear complex possibilities of isomerism in the rotaxanes.

Syntheses

There are basically three ways to display rotaxanes.

Pseudorotaxanes and Semirotaxane

As pseudorotaxanes such rotaxanes be referred in which the set is not prevented by the macrocycle threaded terminal groups of the molecule from leaving its position, but by the interaction with the molecule on the macrocycle is threaded.

As Semirotaxane such rotaxanes are referred to, in which the macrocycle is restrained only by the terminal groups of the molecule on which it is threaded, on leaving his position.

Nomenclature

G. Schill made ​​1971 a proposal for nomenclature of rotaxanes, 2000 suggested Fritz Vogtle and others a more advanced form of this nomenclature, both proposals regulate the nomenclature but not entirely clear. An IUPAC recommendation for the unique nomenclature of rotaxanes was published in 2009.

Application

Rotaxanes are possible as switches and motors for nanotechnology of interest.