The 13C nuclear magnetic reference chemical shifts of (7,0), (8,0), (9,0) and (10,0) single-walled carbon nanotubes with Stone-Wales defects were studied computationally using a gauge-including projector-augmented plane-wave density functional theory method. A Stone-Wales defect substantially broadened the nuclear magnetic reference signal of a particular tube. In general, the average shift of the non-defect carbons did not differ greatly from that of pristine specimens. So-called parallel orientations of the defect site yielded shifts at around 150 to 160ppm from atoms in the defect site which were separated from the rest of the nuclear magnetic reference signal. The results indicated that 13C nuclear magnetic might be able to detect the presence of, and perhaps quantify, Stone-Wales defect concentrations in single-walled carbon nanotubes. Differences in the nuclear magnetic obtained for two defect orientations were analyzed by comparing the shifts of the defect atoms with those of planar and bent structures of the azupyrene molecule. Representative visualizations of the shielding tensors of (8,0) single-walled carbon nanotubes with and without defects were reported.

Density Functional Study of the 13C NMR Chemical Shifts in Single-Walled Carbon Nanotubes with Stone-Wales Defects. E.Zure, C.J.Pickard, J.Autschbach: Journal of Physical Chemistry C, 2008, 112[31], 11744-50