Theoretical investigation of C60 fullerene functionalization with tetrazine

In addition to the known adducts of the C60 with 3,6-diaryl-1,2,4,5-tetrazines, in the present work some other 3,6-disubstituted tetrazines of variable electron withdrawing and donating character were studied theoretically. Here the molecular structure and electronic properties were predicted for –CH3, –NH2, –Ph, –NO2, and –CN substituted tetrazines. The reaction energies were calculated for molecules with different functional groups and found to be in the range of −1.26 to −2.17 eV. Based on the results the relative magnitude order follows: –NO2 > –CN > –H > –CH3 > –NH2 > –Ph, suggesting that the reaction energy is increased by increasing the electron withdrawing character of the functional groups. Unlike traditional behavior of C60 as an electron-deficient dienophile in Diels–Alder reactions, it has been predicted that in the studied reactions it can act as an electron rich agent. The HOMO/LUMO energy gap of the C60 can be decreased by the chemical modification with the tetrazine containing –NH2. Also, the field emission from the C60 may be facilitated upon the adsorption of tetrazines with electron donating groups of –CH3, –NH2, and –Ph.