The Investigation On Fullerene Derivatives

Due to the fact of the special structure and great potential applications, the fullerene derivatives have being attracted intense attentions of physicists, chemists and materials scientists. The structure features and characteristic of Ce₂@C₈₀ , the derivatives of C₂₈, C₄₀ and C₅₆, which all belong to T_d symmetry and the hydrogenated C₇₀, are investigated in this dissertation.1) In this paper, the configurations of Ce₂@C₈₀ have been investigation on DFT (density function theory) level using Amsterdam density functional (ADF) package. The relativistic effects and the frozen-core approximation are taken into account by the zero-order regular approximation (ZORA) basis sets. Interestingly, calculation results show that the most stable Ce₂@C₈₀ configuration is C_2h' , the D_5d configuration is the most unstable with a relative energy about 11kcal/mol higher than the C_2h' configuration. The circle moving can occur at room temperature.2) An investigation on the geometrical and electronic structures of C₂₈, C₄₀, C₅₆ and the N-substituted fullerenes has been performed using the density-functional theory at B3LYP/6-31G* level. Their equilibrium structures, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and aromaticities have been studied. Calculations show that the nitrogen atom has a tendency to substitute the site where carbon is shared by 3 pentagons. The stability order of N-substituted fullerenes is 5/5/5 >5/5/6>5/6/6>6/6/6, which is discussed from the geometrical and electronic factors. The substitutional nitrogen also affects the HOMO, LUMO and aromaticity.3) By study for the interaction between C₇₀ and X (X=H and F), and the potential energy surface, attachment of X is to the five distinct carbons formed radicals C₇₀X.The structures and energies are further discussed thermodynamically and kinetically using density function theory method at B3LYP/631G level. The results appear that stable isomer sequences are the same, being both a kinetic and thermodynamic product of hydrogenation and halogenation reactions. Based on the comparison of spin density, excellent explanation is provided on structural C₇₀X₂ derivatives.