Assigning the major isomers of fullerene C88 by theoretical 13C NMR spectra

The IPR isomers of fullerene C88 have been studied using density functional theory. Structures of all C88 isomers with non-zero HOMO–LUMO gaps were optimized at the B3LYP/STO-3G level. Those isomers having energies lower than 25 kcal/mol were subjected to geometry optimization using the 6-31G basis set. Isomer 17 has the lowest energy, followed by 7 and 33. All three isomers have large HOMO–LUMO gaps. 13C NMR chemical shifts were obtained employing the GIAO method. The comparison between predicted and measured NMR spectra strongly supports the observed C88-1(Cs) as isomer 17, and isomers C88-2(C2) and C88-3(C2) as 7 and 33, respectively.