This article reviews the electronic and transport properties of carbon nanotubes. The focus is mainly theoretical, but when appropriate the relation with experimental results is mentioned. While simple band-folding arguments will be invoked to rationalize how the metallic or semiconducting character of nanotubes is inferred from their topological structure, more sophisticated tight-binding and ab initio treatments will be introduced to discuss more subtle physical effects, such as those induced by curvature, tube-tube interactions, or topological defects. The same approach will be followed for transport properties. The fundamental aspects of conduction regimes and transport length scales will be presented using simple models of disorder, with the derivation of a few analytic results concerning specific situations of shortand long-range static perturbations. Further, the latest developments in semiempirical or ab initio simulations aimed at exploring the effect of realistic static scatterers chemical impurities, adsorbed molecules, etc. or inelastic electron-phonon interactions will be emphasized. Finally, specific issues, going beyond the noninteracting electron model, will be addressed, including excitonic effects in optical experiments, the Coulomb-blockade regime, and the Luttinger liquid, charge density waves, or superconducting transition.

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Electronic and transport properties of nanotubes

Isokinetic relationship, isoequilibrium relationship, and enthalpy-entropy compensation.

We report the direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the MEM (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements. The obtained MEM electron density revealed that van der Waals dimers of physisorbed O2 locate in the middle of nanochannels and form a one-dimensional ladder structure aligned to the host channel structure. The observed O–O stretching Raman band and magnetic susceptibilities are characteristic of the confined O2 molecules in one-dimensional nanochannels of CPL-1 (coordination polymer 1 with pillared layer structure).

https://science.sciencemag.org/content/sci/298/5602/2358.full.pdf

Formation of a one-dimensional array of oxygen in a microporous metal-organic solid

Carbon nanotubes have drawn tremendous interest from fields ranging from condensed-matter physics to chemistry, and from both academia and industry, because of the unique properties enabled by their nanoscale structure. In this paper, I briefly outline the earlier studies concerning carbon nanotubes, and then discuss recent studies done in our laboratories.

Carbon nanotubes: past, present, and future

Curved pi-conjugation, aromaticity, and the related chemistry of small fullerenes (< C60) and single-walled carbon nanotubes.

The geometry of carbon cages (fullerenes) is governed by the isolated-pentagon rule (IPR)1,2, which states that the most stable fullerenes are those in which all pentagons are surrounded by five hexagons. Although this rule has been verified experimentally3,4,5, it is impossible for fullerenes in the range C60 to C70 to obey it. Here we describe the production and characterization of an IPR-violating metallofullerene, Sc2@C66, a C66 fullerene encaging a scandium dimer. Our results indicate that encapsulation of the metal dimer significantly stabilizes this otherwise extremely unstable C66 fullerene.

C66 fullerene encaging a scandium dimer

Three isomers of yttrium carbide (Y2C2) endohedral metallofullerenes, i.e., (Y2C2)@C82(I, II, III), have been synthesized and chromatographically isolated for the first time. The structures of (Y2C...

Trapping a C2 radical in endohedral metallofullerenes: Synthesis and structures of (Y2C2)@C82 (isomers I, II, and III)

Here we report the first {sup 13}C-NMR results on the metallofullerene, Sc{sub 2}@C{sub 84}, which determines an isomer cage structure for the metallofullerene. The Sc{sub 2}@C{sub 84} fullerene was separated and isolated from the various hollow fullerenes (C{sub 60}-C{sub 110}) and other scandium metallofullerenes by the multistage high-performance liquid chromatography (HPLC) method by using two complementary types of HPLC columns. The purity of Sc{sub 2}@C{sub 84} relative to other fullerenes was more than 99.9%. {sup 13}C-NMR measurements were made using a 600 MHz NMR (JEOL JNM-A600) at room temperature in CS{sub 2} solvent. 30 refs., 3 figs.

Tetsuo Tomiyama

Papers

C66 fullerene encaging a scandium dimer

Trapping a C2 radical in endohedral metallofullerenes: Synthesis and structures of (Y2C2)@C82 (isomers I, II, and III)

{sup 13}C-NMR study on the structure of isolated Sc{sub 2}@C{sub 84} metallofullerene

EELS and 13C NMR characterization of pure Ti2@C80 metallofullerene.

Production and isolation of an ellipsoidal C80 fullerene