Reactivities of Sites on (5,5) Single-Walled Carbon Nanotubes with and without a Stone-Wales Defect

The reactivities of various carbon sites on (5,5) single-walled carbon nanotubes (SWCNT) of C70H20 with and without a Stone-Wales defect have been predicted computationally. The properties determined include the average local ionization energy I̅s(r) and pyramidalization angle θP on the surfaces of the bare tubes, the chemisorption energies, bond lengths, stretching frequencies for chemisorbed H and F atoms, and the effects of H and F chemisorption upon the HOMO−LUMO energy gaps. There is a good correlation between the minima of the local ionization energy and the chemisorption energies at different carbon sites, indicating that I̅s(r) provides an effective means for rapidly and inexpensively assessing the relative reactivities of the carbon sites of SWCNTs. The pyramidalization angle (θP), which is a measure of local curvature, also shows a relationship to site reactivity. The most reactive carbon site, identified by having the lowest I̅s(r) and largest θP, is in the Stone-Wales defect region, which also has the least reactive carbon site, having the highest I̅s(r) and smallest θP. The presence of a Stone-Wales defect and also by H and F chemisorption decreased the HOMO−LUMO gap of (5,5) SWCNT.