The Structural Characterizations And DFT Calculations Of Fullerenes And Endohedral Fulleneres

This dissertation briefly reviews the progress of the structure features, methods of synthesis, isolations and characterizations of fullerenes and endohedral fullerenes, as well as the applications of quantum chemical calculation in the field of fullerenes. At the same time, the dissertation also provides a review on the application prospects of fullerenes and endohedral fullerene complexes in the fields of material and biomedical sciences.In this dissertation, we developed a series of methods including graphite arc discharging on graphite rods doped with Sm2O3, o-dichlorobenzene extraction with ultrasonication aiding and multi-stage HPLC isolations without recycling, and obtained one C86and two C90empty fullerene isomers. The obtained samples were successfully grown cocrystalizing with Ni(OEP), and synchrotron X-ray diffraction measurements on the single crystals were carried out, followed by structure resolution. The relative results revealed that the C86sample is a mixture of the C5(16)-C86and C2(17)-C86, and both occupied in the same position of the cocrystal. Structural similarities have been found in these two isomers, which are linked together through a one step Stone-Wales transformation. The DFT calculation results indicated that the region in blue with relative deficient electrons in the plots of electrostatic potential mapped on the electron density isosurface of C5(16)-C86was contacted with the reversed region in red with relative rich electrons of the porphyrin center. These interactions afforded the construction of the cocrystal. In addition, the Kohn-Sham orbital plots from the DFT calculations for the system of Cs(16)-C86-Ni"(OEP) showed that there were covalent interactions between the C86cage and metal porphyrin. The interaction of HOMO-6and HOMO-11belonged to σ covalence, while that of HOMO-18and HOMO-26belonged to three centric covalences, which demonstrated that the other carbons of the cage were involved in the formation of the covalence, beside the nearest carbon to the metal porphyrin. The isolated two isomers of C90were identified to be C1(32)-C9o and C1(30)-C90, which are chiral isomers with C1symmetry, without any geometric symmetry. These two isomers are also linked together through a one step Stone-Wales transformation. Using the similar methods mentioned above, four isomers of Sm@C9o were also prepared isolated and characterized. The X-ray single crystal diffraction measurements on the four cocrystals of the endohedral samples with (OEP)Ni were performed, and the structures of the four isomers were solved to be Sm@C2(4O)-C9o%Sm@C2(42)-C90、Sm@C2v(46)-C90, and Sm@C2(45)-C90, respectively, which are linked to a chain through a series of continued one step Stone-Wales transformations. The results of the DFT calculations on these four isomers demonstrated that the relative energies of the isomers were almost linear with respect to the experimental observed abundances, which implied that the isomers may be in chemical equilibrium condition during their formations.Systemic calculations at DFT for the endohedral fullerenes have been conducted. The geometries of the D5h,(1)-C9o which was introduced one or CO molecules have been optimized, and the bond lengths and bond angles of the endohedral complexes, and the combination energies have been obtained, and it has been found that the endohedrals possessed a little bit stabilities.The geometries of the C70-.D5h which was introduced one or two carbenes have been calculated using DFT method, and the comparisons of these isomers’structure and energy in bond length, bond angle, dihedral angle and relative distance of carbene have been done. The comparisons of their energy levels were also made for the hollow C70-D5h, cage, single carbene endohedral fullerenes and two bi-carbene endohedral fullerenes. The relative chemical properties and stabilities were analyzed. Calculations for C60-Ih cage, which was introduced the CH2, SiH2, GeH2to both inside and outside, have been carried out. The results of energies and electronic structures of these configurations indicated that the derivates based on the C60Ih after introducing the MH2groups showed more chemical activities, and more electrophilic abilities.Full geometric optimizations without symmetric restriction at B3LYP and MP2level for X@C6o (X is the atoms whose atomic number were less than or equal to36) have been conducted, and the results showed that the coincidence between the energies and atomic numbers was more regular, and most of the configurations possessed the negatively conditional energies, which predicts that some of then may be synthesized experimentally.