Mono- and multiply-functionalized fullerene derivatives through 1,3-dipolar cycloadditions: A DFT study

We have performed a computational study to investigate the electronic and chemical properties of mono- and multiply-functionalized fullerene derivatives through the [2+3] cycloaddition reactions of 1,3 dipoles such as nitriloxide (HCåN+–O−), azide (NåN+–NH−) and azomethine ylides (H2C–+NH–CH2−) with C60 fullerene. The 1,3-dipolar cycloadditions (1,3 DCs) of one to six dipoles with a C60 molecule are theoretically investigated in terms of geometry, energies, electronic structures, stability and the electrophilicity index. Negative values of reaction energies Er are obtained, which indicate the exothermic character of the adsorption process. Generally, absolute values of Er for the C60/(H2C–+NH–CH2−)n compounds are always larger than those of their corresponding compounds C60/(HCåN+–O−)n and C60/(NåN+–NH−)n. The results indicate that the successive 1,3-DC reactions of nitriloxides (HCåN+–O−) and azides (NåN+–NH−), n=1,2, 4 and 6 on the exterior surface of fullerene increases the electrophilicity while the reverse trend is observed for C60/(H2C–+NH–CH2−)n. Furthermore, electrophilicity values for the C60/(HCåN+–O−)n and C60/(NåN+–NH−)n compounds are always greater than those of C60.