Determining the diameter of functionalized single-walled carbon nanotubes with¹³C 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.