Determining the Diameter of Functionalized Single-Walled Carbon Nanotubes with 13C NMR: A Theoretical Study

NMR chemical shifts of N–R-functionalized (n, 0) single-walled carbon nanotubes (SWNTs) with n = 11, 13−17 were computed from first principles. The chemical shifts of functionalized carbons at a bond diagonal to the SWNT axis are strongly dependent upon the C−C distance in the C−NR−C moiety. This distance, in turn, is sensitive to the SWNT radius. Monitoring these shifts could therefore help to determine the diameter distribution within a sample. Proton shifts are also reported.