Calculations of the geometries, electronic structures and nonlinear second-order optical susceptibilities of spiroannelated quinone-type methanofullerenes

Abstract

The equilibrium geometries, electronic structures and UV±vis spectra of a series of spiroannelated quinone-type methanofullerenes have been determined by using Zerner's intermediate neglect of dierential overlap method. The results show that between fullerene and the addend there exists a special interaction,`p ericonjugation'', which results in through-space orbital interactions. The calculated UV±vis spectra are in good agreement with experiments. On the basis of the electronic spectra, the b values are calculated. The results show that spiroannelated quinone-type methanofullerenes have quite large b values. We attribute the large b values to both the charge transfer from C 60 to benzoquinone and on the C 60 three-dimensional conjugated sphere.Here P i is the molecular polarization induced along the ith axis, E j is the jth component of the applied electric ®eld, a is the linear polarizability, b is the ®rst hyperpolarizability or the second-order susceptibility and c is the second hyperpolarizability or the thirdorder susceptibility. a, b and c describe the responsivity of the molecule to an electromagnetic perturbation and are constants for Correspondence to: J.-K. Feng Regular articleCalculations of the geometries, electronic structures and nonlinear second-order optical susceptibilities of spiroannelated quinone-type methanofullerenes