Pentagon junctions

An interesting illustrative example is supplied with computations [143] of C32. There are just six conventional C32 cages built from pentagons and hexagons [348]. As no IPR structures are possible for C32, a pentagon/pentagon junction will always be present. Their number can be reduced by introduction of four-membered and/or seven-membered rings. Euler s network closure requirement reads then ... 

The k p scheme has been used also for the study of transport across junctions connecting tubes with different diameters through a region sandwiched by a pentagon-heptagon pair [25]. In Junctions systems, the conductance was predicted to exhibit a universal power-law dependence on the ratio of the circumference of two CNTs [26]. An intriguing dependence on the magnetic-field direction was predicted also [27]. These newer topics will be discussed elsewhere. 

Nanometer-Sized Electronic Devices The possible use of carbon nanotubes in nanoelectronics has aroused considerable interest. Dramatic recent advances have fueled speculation that nanotubes (SWNTs) will be useful for downsizing circuit dimensions. Because of their unique electronic properties, SWNTs can be interfaced with other materials to form novel heterostructures [156]. The simplest device one can imagine with carbon nanotubes is that involving a bend or a kink, arising from the presence of a diametrically opposite pentagon-heptagon pair. The resultant junction connects two nanotubes of different chirality and hence of different electronic structure, leading to the realization of an intramolecular device. Such a device in SWNTs is found to behave like a diode rectifier [157]. Silicon nanowire-carbon nanotube heterojunctions do indeed exhibit a rectification behavior [158]. 

Plateau showed that the vertices of the neighboring pentagonal dodecahedrons form junction comer in which four borders join. As a result, four vertices closest to the reference one form a tetrahedron. This arrangement is similar to that of atoms in the nearest coordination sphere in the diamond crystal lattice. The borders and nodes form a united branched network along which the transfer of dispersion medium, including drainage under gravity, may take place. 

Another stabilizing feature is the abihty to stabilize nonisolated pentagon rule fullerenes when a metal or cluster is encapsulated. All empty ftillerenes to date obey the isolated pentagon rule, in that there are no [5, 5] junctions that cause strain that destabilizes the molecule, because all pentagons are connected to hexagons. Nonisolated pentagon rule endohedral fullerenes such as Sc2 C66 and ScjN C68 are known to exist. ... 

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