En este trabajo abarcamos el estudio de la estructura electrónica de una serie de fulerenos denominados fulerenos endoédricos, así como también su reactividad. En este trabajo de tesis previo, se define lo que se conoce como la regla del gap (LUMO-3)-(LUMO-4), la cual indica que aquellas cajas fulerénicas vacías cuyo gap entre el tercer y cuarto orbitales desocupados sea mayor grande tendrán la capacidad de aceptar la transferencia de seis electrones desde un clúster metálico. En el capítulo 3, la regla del gap (LUMO-3)-(LUMO-4) ha sido extendida para aquellas cajas fulerénicas de hasta 100 átomos de carbono. También se ha analizado la reactividad exoédrica del M3N@D5h-C80 en una reacción de cicloadición de Diels-Alder con 1, 3-butadieno sobre los diferentes tipos de enlaces de la caja D5h-C80. En el capítulo 4 estudiamos la estructura electrónica de los fulerenos endoédricos con carburos metálicos (M2C2@C82). Se han estudiado seis isómeros de Sc2C2@C82, confirmando que su estructura electrónica se puede explicar de manera sencilla con el modelo iónico (clúster)4+@(caja)4–, adoptando el carburo metalico diferentes orientaciones dentro de la caja de C82 . En el capítulo 5 hemos estudiado la estructura y propiedades electrónicas de una otras dos famílias de fulerenos endoédricos: la de los óxideos de escandio y la de los sulfuros de escandio. Por último hemos estudiado las propiedades electroquímicas de una serie de fulerenos endoédricos con diferentes clústeres (capítulo 6). Los orbitales frontera y las propiedades redox de Sc3N@C80 son diferentes cuando son comparados con fulerenos endoédricos de metales más electro positivos (Gd e Y). / We have extended the application of the general rule for the stabilization of nitride EMFs proposed by Campanera et al. to IPR carbon cages of dimensions up to C100. This simple rule, based on the formal transfer of six electrons from the cluster to the carbon cage, can be seen as an empirical rule that is able to predict the most abundant cage isomer for all the nitride EMFs known to date. Some EMF with M2 clusters, however, seem to escape this simple rule. We have proposed six large carbon cages (from C92 to C100) with sizeable (LUMO-4)–(LUMO-3) gaps and achievable energies as candidates for encapsulating metal nitride units or M2 clusters on condition that the formal six-electron transfer and other factors are accomplished. We have confirmed that the ionic model based on the formal transfer of four electrons from the encapsulated M2C2 carbide to the carbon cage is valid for the M2C2@C82 family. We have observed that the internal metal- carbide cluster is able to rotate inside the carbon cage. Using the aforesaid ionic model we have understood the higher stability of M2C2@C82 (C3v:8) when compared to carbide endohedrals with other IPR C82 isomers. The electrochemical properties for a series of EMFs have been studied theoretically. Analogously to the neutral M3N@Ih-C80 (M = Sc and Y) systems, rotation of the M3N unit inside the fullerene cage is predicted for the neutral, oxidized and reduced states of all the nitride EMFs with IPR cages studied through this work (from Sc3N@D5h-C80 to La3N@C96).

Nowadays, material, energy and information technologies are three pillar industries. The materials that have close relation with our life have also been the foundation for the development of energy and information technologies. As the new member of the material family, functional molecular materials have become increasingly important for many applications, for which the design and characterization by the theoretical modeling have played the vital role. In this thesis, three different categories of functional molecular materials, the endohedral fullerenes, the fullerene derivatives and the self-assembled monolayers (SAMs), have been studied by means of first principles methods. The non-metal endohedral fullerene N@C60 is a special endohedral fullerene that is believed to be relevant to the construction of future quantum computer. The energy landscape inside the N@C60 has been carefully explored by density functional theory (DFT) calculations. The most energy favorable potential energysurfaces (PESs) for the N atom to move within the cavity have been identified. The effect of the charging on the PESs has also been examined. It is found that the inclusion of dispersion force is essential in determining the equilibriumstructure of N@C60. Furthermore, the performance of several commonly useddensity functionals with or without dispersion correction has been verified for ten different endohedral fullerenes A@C60 with the atom A being either reactive nonmetal or nobel gases elements. It shows that the inclusion of the dispersion forcedoes provide better description for the binding energy (BE), however, none ofthem could correctly describe the energy landscape inside all the ten endohedral fullerenes exclusively. It thus calls for the further improvement of current density functionals for weak interacting systems. Soft X-ray spectroscopy is a powerful tool for studying the chemical and electronic structures of functional molecular materials. Theoretical calculations have been proven to be extremely useful for providing correct assignments for spectraof large systems. In this thesis, we have performed first principles simulations forthe near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectra (XPS) of fullerene derivatives and aminothiolates SAMs. Our calculatedspectra can accurately reproduce experimental results available for all the systemsunder investigations, and identify the species or structures that are responsible for those unexpected spectral features observed in experiments. We have suggested a modified building block (MBB) approach that allows to calculate NEXAFS spectraof a large number of fullerene derivatives with very small computational cost, and resolved the long standing puzzle around the experimental XPS and NEXAFS spectra of SAMs with aminothiolates. / <p>QC 20120523</p>

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20393号 / 工博第4330号 / 新制||工||1671(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 村田 靖次郎, 教授 小澤 文幸, 教授 近藤 輝幸 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Quantum information processing (QIP), which inherently utilizes quantum mechanical phenomena to perform information processing, may outperform its classical counterpart at certain tasks. As one of the physical implementations of QIP, the electron-spin based architecture has recently attracted great interests. Endohedral fullerenes with unpaired electrons, such as N@C₆₀, are promising candidates to embody the qubits because of their long spin decoherence time. This thesis addresses several fundamental aspects of the strategy of engineering the N@C₆₀ molecules for applications in QIP. Chemical functionalization of N@C₆₀ is investigated and several different derivatives of N@C₆₀ are synthesized. These N@C₆₀ derivatives exhibit different stability when they are exposed to ambient light in a degassed solution. The cyclopropane derivative of N@C60 shows comparable stability to pristine N@C₆₀, whereas the pyrrolidine derivatives demonstrate much lower stability. To elucidate the effect of the functional groups on the stability, an escape mechanism of the encapsulated nitrogen atom is proposed based on DFT calculations. The escape of nitrogen is facilitated by a 6-membered ring formed in the decomposition of the pyrrolidine derivatives of N@C₆₀. In contrast, the 4-membered ring formed in the cyclopropane derivative of N@C₆₀ prohibits such an escape through the addends. Two N@C₆₀-porphyrin dyads are synthesized. The dyad with free base porphyrin exhibits typical zero-field splitting (ZFS) features due to functionalization in the solid-state electron spin resonance (ESR) spectrum. However, the nitrogen ESR signal in the second dyad of N@C₆₀ and copper porphyrin is completely suppressed at a wide range of sample concentrations. The dipolar coupling between the copper spin and the nitrogen spins is calculated to be 27.0 MHz. To prove the presence of the encapsulated nitrogen atom in the second dyad, demetallation of the copper porphyrin moiety is carried out. The recovery of approximately 82% of the signal intensity confirms that the dipolar coupling suppresses the ESR signal of N@C₆₀. To prepare ordered structure of N@C₆₀, the nematic matrix MBBA is employed to align the pyrrolidine derivatives of N@C₆₀. Orientations of these derivatives are investigated through simulation of their ESR spectra. The derivatives with a –CH3 or phenyl group derived straightforward from the N-substituent of the pyrrolidine ring are preferentially oriented based on their powder-like ESR spectra in the MBBA matrix. An angle of about is also found between the directors of fullerene derivatives and MBBA. In contrast, the derivatives with a –CH₂ group inserted between the phenyl group and the pyrrolidine ring are nearly randomly distributed in MBBA. These results illustrate the applicability of liquid crystal as a matrix to align N@C₆₀ derivatives for QIP applications.

Nous avons synthétisé différentes dyades donneurs-accepteurs (D-A) π-conjuguées à base de fullerène pour des applications photovoltaïques dans lesquelles les unités D étaient soit des oligophenylenevinylenes (OPV) soit des oligophenyleneethynylene (OPE) et les unités A étaient le C60 ou un endofullerène du type Y3N@C80. Il y avait une exigence supplémentaire pour nos matériaux, à savoir qu’ils devaient s’auto-organiser en phases liquides-cristallines. Pour ce faire, toutes les unités D contenaient un promoteur mésogène afin d'induire le mésomorphisme de la dyade D- et donc de contrôler la morphologie des couches minces nécessaires à l’élaboraiton des cellules photovoltaïques grâce à une organisation supramoléculaire. En dehors de cela, nous avons étudié l’influence de la nature chimique du donneur (par exemple lyophile ou amphiphile), de la longueur des oligomères et de la multiaddition sur les propriétés photophysiques et sur l'auto-assemblage. Nous avons synthétisé une dyade OPE-Y3N@C80 qui est le premier dérive mésomorphe et photosensible de ce type de métallofullerène endohédral. / We have synthesized different π-conjugated system-fullerene dyads for photovoltaic applications, where the donor units were either oligophenylenevinylene (OPV) or oligophenyleneethynylene (OPE) derivatives and for the acceptor, C60 or Y3N@C80 was used. There was an additional requirement for our materials: liquid crystallinity. All the donor units contained a mesogenic promoter in order to induce mesomorphism in the D-A dyad and to control the morphology of the prepared film through supramolecular organization. Apart from that, we investigated the effect of the chemical nature of the donor moiety (ie. lyophilic or amphiphilic), the oligomeric length and multiaddition on the photophysical properties and on the self-assembly. We have synthesized an OPE-Y3N@C80 dyad which is the first trimetallic nitride template endohedral metallofullerene derivative with mesomorphic and photoactive properties.