Unraveling the 13C NMR Chemical Shifts in Single-Walled Carbon Nanotubes: Dependence on Diameter and Electronic Structure
The atomic specificity afforded by nuclear magnetic resonance (NMR) spectroscopy could enable detailed mechanistic information about single-walled carbon nanotube (SWCNT) functionalization as well as the noncovalent molecular interactions that dictate ground-state charge transfer and separation by electronic structure and diameter. However, to date, the polydispersity present in as-synthesized SWCNT populations has obscured the dependence of the SWCNT {sup 13}C chemical shift on intrinsic parameters such as diameter and electronic structure, meaning that no information is gleaned for specific SWCNTs with unique chiral indices. In this article, we utilize a combination of {sup 13}C labeling and density gradient ultracentrifugation (DGU) to produce an array of {sup 13}C-labeled SWCNT populations with varying diameter, electronic structure, and chiral angle. We find that the SWCNT isotropic {sup 13}C chemical shift decreases systematically with increasing diameter for semiconducting SWCNTs, in agreement with recent theoretical predictions that have heretofore gone unaddressed. Furthermore, we find that the {sup 13}C chemical shifts for small diameter metallic and semiconducting SWCNTs differ significantly, and that the full-width of the isotropic peak for metallic SWCNTs is much larger than that of semiconducting nanotubes, irrespective of diameter.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science, Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, Solar Photochemistry Program
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1039100
- Report Number(s):
- NREL/JA-5900-54753; JACSAT; TRN: US201209%%163
- Journal Information:
- Journal of the American Chemical Society, Vol. 134, Issue 10; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
77 NANOSCIENCE AND NANOTECHNOLOGY
CARBON
CHEMICAL SHIFT
ELECTRONIC STRUCTURE
NANOTUBES
NUCLEAR MAGNETIC RESONANCE
SPECIFICITY
SPECTROSCOPY
ULTRACENTRIFUGATION
nuclear magnetic resonancy
NMR
single walled carbon nanotube
SWCNT
parameters
diameter
electronic structure