Solution Properties of Single-Walled Carbon Nanotubes

Abstract

Naked metallic and semiconducting single-walled carbon nanotubes (SWNTs) were dissolved in organic solutions by derivatization with thionychloride and octadecylamine. Both ionic (charge transfer) and covalent solution-phase chemistry with concomitant modulation of the SWNT band structure were demonstrated. Solution-phase near-infrared spectroscopy was used to study the effects of chemical modifications on the band gaps of the SWNTs. Reaction of soluble SWNTs with dichlorocarbene led to functionalization of the nanotube walls.

Chemistry of Single-Walled Carbon Nanotubes

“…29 Electronic transitions between the energy bands of SWNTs ( Figure 2) can be observed by standard spectroscopic techniques. 7,27,30 Besides the heterogeneity of the samples with respect to the tube diameters and helicities, impurity doping contributes to the breadth of the absorption features. 27 Since the band gaps are inversely proportional to the tube diameters, structural information can be derived from the band transition energies.…”

“…106,107 Electronic spectroscopy showed that the band-gap transitions in the semiconducting tubes were completely disrupted at a functionalization level of 2% of the available SWNT carbon atoms. 7 Apart from the carbene chemistry, 6 97 While the side walls of the carbon nanotubes were once considered impregnable (like the fullerenes), 32,33 there is now an extensive chemistry, 7,93,94,96,97,110 and these initial studies suggest that the chemistry of the carbon nanotubes will ultimately rival that of the carbon fullerenes.…”

“…Similar effects may be observed by doping solutions of the nanotubes with halogens. 7,83 Under saturation doping, 7 bromine and iodine completely deplete the electrons from the valence band responsible for the S 11 transition in the semiconducting nanotubes, and both reagents also affect the S 22 transition ( Figure 5). Similar results were obtained under electrochemical cycling 63 and by controlled doping of thin films of carbon nanotubes.…”

“…It has been the goal of our group to bring these fascinating onedimensional (1D) carbon structures into the fold of (macro)molecular chemistry. 6 Recent work has shown that with appropriate processing carbon nanotubes may take on properties that are normally associated with molecular species, 7 such as solubility in organic solvents, solutionbased chemical transformations, chromatography, and spectroscopy. In this Account we summarize the progress and the promise of the new field of carbon nanotube chemistry.…”

Purification, Functionalization, and Bioconjugation of Carbon Nanotubes

“…The resulting CNTs that are obtained typically display lengths ranging from 100 to 300 nm, with both ends and the sidewalls decorated predominantly with a high density of carboxyl groups. In an alternative oxidation protocol (Subheading 3.3.2), nanotube shortening can be minimized by refluxing the CNTs in concentrated nitric acid alone (33). Using this approach, the resulting CNTs have most of their pristine mechanical and electrical properties preserved; however, oxidation only occurs at the opening of the tube caps and carboxylic acid functional groups are only formed at defect sites found along the sidewalls.…”