A quantum chemical study of the reactivity of the 7-5-5-7 topological defect, corresponding to a carbon ad-dimer, on a (5,5) armchair nanotube was performed. The energies indicated that the defect was more reactive, by 46 to 70kcal/mol, towards adsorbates containing π-bonds, such as C2H4, O2 and O3, than were pristine nanotubes or the Stone-Wales 5-7-7-5 defect. The enhanced reactivity of this defect was also deduced for other sizes and types of carbon nanotube.

Increased Reactivity of Single Wall Carbon Nanotubes at Carbon Ad-Dimer Defect Sites. D.A.Horner, P.C.Redfern, M.Sternberg, P.Zapol, L.A.Curtiss: Chemical Physics Letters, 2007, 450[1-3], 71-5