Semiconducting and Metallic [5,5] Fullertube Nanowires: Characterization of Pristine D5h(1)-C90 and D5d(1)-C100

Although fullerenes were discovered nearly 35 years ago, scientists still struggle to isolate single molecule tubular fullerenes larger than C-90. In similar fashion, there is a paucity of reports for pristine single-walled carbon nanotubes (SWNTs). In spite of Herculean efforts, the isolation and properties of pristine members of these carbonaceous classes remain largely unfulfilled. For example, the low abundance of spherical and tubular higher fullerenes in electric-arc extracts (<0.01-0.5%) and multiplicity of structural isomers remain a major challenge. Recently, a new isolation protocol for highly tubular fullerenes, also called fullertubes, was reported. Herein, we describe spectroscopic characterization including C-13 NMR, XPS, and Raman results for purified [5,5] fullertube family members, D-5h-C-90 and D-5d-C-100. In addition, DFT computational HOMO-LUMO gaps, polarizability indices, and electron density maps were also obtained. The Raman and C-13 NMR results are consistent with semiconducting and metallic properties for D-5h-C-90 and D-5d-C-100, respectively. Our report suggests that short [5,5] fullertubes with aspect ratios of only similar to 1.5-2 are metallic and could exhibit unique electronic properties.

Automated summary

Despite efforts to isolate larger tubular fullerenes and pristine single-walled carbon nanotubes, challenges persist in both their isolation and property studies. A new isolation protocol for highly tubular fullerenes has been reported, along with spectroscopic characterization of [5,5] fullertube family members.