Unraveling the 13C NMR Chemical Shifts in Single-Walled Carbon Nanotubes: Dependence on Diameter and Electronic Structure

Chaiwat Engtrakul, Veronica M. Irurzun, Erica L. Gjersing, Josh M. Holt, Brian A. Larsen, Daniel E. Resasco, Jeffrey L. Blackburn

Research output: Contribution to journalArticlepeer-review

16 Scopus Citations


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 13C 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 13C labeling and density gradient ultracentrifugation (DGU) to produce an array of 13C-labeled SWCNT populations with varying diameter, electronic structure, and chiral angle. We find that the SWCNT isotropic 13C 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 13C 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.

Original languageAmerican English
Pages (from-to)4850-4856
Number of pages7
JournalJournal of the American Chemical Society
Issue number10
StatePublished - 14 Mar 2012

NREL Publication Number

  • NREL/JA-5900-54753


  • diameter
  • electronic structure
  • NMR
  • nuclear magnetic resonancy
  • parameters
  • single walled carbon nanotube


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