Stone–Wales defect
![](http://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Naphthalene-fulvalene_fullcolor.png/220px-Naphthalene-fulvalene_fullcolor.png)
A Stone–Wales defect is a crystallographic defect that involves the change of connectivity of two π-bonded carbon atoms, leading to their rotation by 90° with respect to the midpoint of their bond.[1] The reaction commonly involves conversion between a naphthalene-like structure into a fulvalene-like structure, that is, two rings that share an edge vs two separate rings that have vertices bonded to each other.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/2a/Pyrene_Stone-Wales.png/220px-Pyrene_Stone-Wales.png)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Stone%E2%80%93Wales_defect_in_2D_silica_and_graphene.jpg/220px-Stone%E2%80%93Wales_defect_in_2D_silica_and_graphene.jpg)
The reaction occurs on carbon nanotubes, graphene, and similar carbon frameworks, where the four adjacent six-membered rings of a pyrene-like region are changed into two five-membered rings and two seven-membered rings when the bond uniting two of the adjacent rings rotates. In these materials, the rearrangement is thought to have important implications for the thermal,[3] chemical, electrical, and mechanical properties.[4] The rearrangement is an example of a pyracyclene rearrangement.
History
The defect is named after
Structural effects
The defects have been imaged using
It has been proposed that the coalescence process of fullerenes or carbon nanotubes may occur through a sequence of such a rearrangements.[citation needed] The defect is thought to be responsible for nanoscale plasticity and the brittle–ductile transitions in carbon nanotubes.[citation needed]
Chemical details
The activation energy for the simple atomic motion that gives the bond-rotation apparent in a Stone–Wales defects is fairly high—a barrier of several electronvolts.[4][9] but various processes can create the defects at substantially lower energies than might be expected.[8]
The rearrangement creates a structure with less
References
- PMID 25843555.
- PMID 24336488.
- . Retrieved 31 August 2021.
- ^ hdl:10397/4230.
- .
- .
- ^ Thrower, P.A. (1969). "The study of defects in graphite by transmission electron microscopy". Chemistry and Physics of Carbon. 5: 217–320.
- ^ S2CID 15204799.
- .
- ^ .
External links
Media related to Stone-Wales defect at Wikimedia Commons