THEORETICAL INVESTIGATION ON ANTIRADICAL AND ANTIOXIDANT ACTIVITY OF C40N20 NITROGEN DOPED FULLERENE

Charge transfer between carbon and heteroatoms in heterofullerenes make them potential candidates for variety of reactions which could be quite different from those of basic C60 fullerene. Antioxidant property of fullerenes is restricted due to their low tendency toward peroxy radicals. Anti-radical activity of the nitrogen doped heterofullerenes (except aza-fullerene C59N) has not been so far studied in details. For this purpose, and also taking the effectsof NN bonds on the fullerene anti-radical activity into account, nitrogen doped fullerene C40N20 have been considered in this study. This molecule has been shown to have isomers containing separated nitrogen (SN) atoms with no N-N bonds and isomers comprising a nitrogen belt (NB) with several N–N connections. Interactions of this heterofullerene with several simple C-centered radicals (such as methyl, ethyl, propyl and butyl), H, OH and also methyl peroxy radical have been theoretically investigated.All calculations have been carried out using Gaussian 09 program employing B3LYP/6-31G(d) level of theory. Vibrational frequencies and binding energies which were corrected for basis set superposition error have been also calculated at the same level. The results have been compared for the isomers with N–N connections (NBC40N20), isomer with no N–N bonds (SN-C40N20), and also for C60 fullerene as reference molecule. According to the results, NB-C40N20 exhibits more anti radical activity than C60 fullerene. Also SN-C40N20 could have antioxidant property several times higher thanC60 for liquid-phase hydrocarbons.