By using AM1 semiempirical quantum calculation method, the structures and electronic properties of N-methyl- pyrrolo[3,4]C60(MPC) and N-methyl-2-(2'-dimethylaniline- substituted dithienylen-thylene)- pyrrolo[3,4]C60(TMPC) have been studied. The froniter molecular orbitals of the C60 moiety dominate those of MPC and TMPC. For MPC and TMPC, there exists strong intramolecular electron transfer. The C60 moiety is electron acceptor while the thiophene and pyrrolidine parts are electron donor. Based on the AM1 optimizing geometry, the electronic spectra and seccond- order nonlinear optical polarizabilites (β) of TMPC and MPC are calculated by using INDO/SCI method combined with sum-over-states (SOS) expression. The calculated results reveal that there exist absorption peaks above 400 nm both for TMPC and MPC and those of TMPC are much stronger than those of MPC. For TMPC, β values vary with different isomers.

Key words: ELECTRONIC STRUCTURE, QUANTUM CHEMISTRY, THIOPHENE P, PYRROLIDINE P, FULLERENES, ELECTRON SPECTROSCOPY, TWO-ORDER, NON LINEAR OPTICS