THE STRUCTURE OF HIGHER-ORDER C-60-FULLERENE-GAMMA-CYCLODEXTRIN COMPLEXES

C-60 inclusion complexes in gamma-cyclodextrin are studied by molecula r mechanics and semi-empirical methods with the aim of comparing measu red and calculated induced circular dichroism (ICD) spectra. Low energ y geometries of the complexes are generated by Monte Carlo simulations , also accounting for solvation effects by an aqueous environment. The ICD spectrum of the complex is then obtained from an exciton model ba sed on semi-empirical calculations of the transition energies and the corresponding transition moments. Highly symmetric, tightly bound comp lexes of two gamma-cyclodextrins and buckminsterfullerene are found as the most probable structures. The main bands of the experimentally de rived ICD spectrum are assigned to the excitation transitions of the c hromophore and are discussed in comparison to calculations on the magn etic circular dichroism (MCD) spectrum of C-60.