Theoretical study of molecular and photophysical properties of [5, 6]-open C60 derivatives

Configurations of four [5, 6]-open C60 monoadducts have been optimized at B3LYP/6-31G* level. The calculated geometrical structures show that the bonds at the junction between five- and six-membered rings break and the planar properties of pentagon and hexagon rings in the vicinity of functionalized groups disappear for these C60 derivatives. On the basis of the optimized geometrical structures, their excitation energies and third-order nonlinear optical polarizabilities have been calculated at TDB3LYP/3-21G* level coupled with sum-over-states method for these C60 monoadducts. The obtained results show that different functionalized groups result in different effects on HOMO-LUMO gap and different optical property for [5, 6]-open C60 derivatives. The absorption spectra of the derivatives, in which a nitrogen atom bridges the functionalized groups to C60 cage, show a red shift compared with those of the derivatives in which a carbon atom becomes as the connection.