13C NMR and Fukui function analysis on C82 hydroxylated fullerene through density functional theory

Density functional theory calculations were performed on C-82 hydroxylated fullerene. B3LYP and PBE0 functionals with 6-31G** basis set were utilised to get chemical shieldings, chemical shifts and the isotropic Fermi contact coupling on each atomic site. A relation between nuclear magnetic resonance (NMR) properties and reactivity of the molecule, obtained through the electronic Fukui function, was observed. Interestingly, the most stable configurations of OH groups adsorbed on C-82 surface were obtained when the hydroxyl groups are adsorbed on deshielded (isotropically and anisotropically) sites. For open-shell systems, a relation between isotropic Fermi contact, spin density and average Fukui function was found, that is, sites with a great amount of Fukui function (analytical and the one obtained through finite difference) and spin density have the largest isotropic Fermi contact coupling data. With the adsorption of the first hydroxyl molecules, spin densities and Fukui functions show preferential sites to adsorb the following OH groups close to previously adsorbed. Additionally, theoretical spectra of chemical shifts of C-82(OH)(n) (n = 1, 2, 3 and 4) were obtained and they were compared with experimental reports, getting a reasonable comparison. For example, regarding C-13 NMR chemical shifts obtained in C82OH molecule, 80 ppm (B3LYP) and 79 ppm (PBE0) were calculated on hydroxylated carbon, which is in good agreement with experimental results in C-60 fullerols.