Trends in Structure and Growth of Higher Fullerenes Isomer Structure of C86 and C88-

Abstract

The isomer structure and stability of higher fullerenes is one of the most interesting issues which might be closely related with general question how a fullerene cage structure is formed. In the present study, the structures of the higher fullerenes with the sizes of C₈₆ and C₈₈ are described based on UV/Visible/nearIR absorption spectra and ¹³C NMR measurements in solution. For well-understanding the structure and growth of higher fullerenes, the isomer-free samples were prepared for all isomers associated with the C₈₆, and C₈₈ cages by means of a multiple stage high performance liquid chromatography (HPLC). As a result, five different isomers for C₈₆ and C₈₈ were successfully isolated and characterized. For these five different isomers studied in the present work, ¹³C NMR measurements in solution straightforwardly gave a conclusion that three of them possess the cage structures with a C₂ molecular symmetry and two with a C_s molecular symmetry. The possible specific candidates for these five isomers will be discussed on the basis of both the present experimental results and recent theoretical predictions.