Quantum Chemical Studies of Endofullerenes (M@C60) Where M = H2O, Li+, Na+, K+, Be2+, Mg2+, and Ca2+

Abstract

Quantum chemical calculations were performed to investigate the structural and electronic properties of seven endofullerenes. The interaction energies indicated that all of the chemical species are stable inside the fullerene for each complex. The ionization potential and electron affinity values suggest that the endofullerenes consisting of alkaline earth ions are the most reactive and that the dipole moment decreased according to the following order: Be2+@C60 (4.75) > Mg2+@C60 (3.14) > Ca2+@C60 (2.24) > Li+@C60 (1.26) > Na+@C60 (0.76) > H2O@C60 (0.24) > K+@C60 (0.00 Debye). These results imply that the solubility of endofullerenes in a polar solvent may increase from H2O@C60 to Be2+@C60. The energetic gaps indicate that Be2+@C60 and Mg2+@C60 possess a higher electrical conductivity, and the UV spectra show a shift in the bands to the visible light region. The results of this work may be useful for the development of new endofullerenes.