Electric-arc vaporization of graphite rod/metal (or metal oxide) mixtures in an inert He atmosphere has been the method of choice for the production of endohedral metallofullerenes (Am@C2n). However, yields of endohedral metallofullerenes have been limited to only a few percent of the total fullerene yield, making the production and isolation of macroscopic quantities (grams) difficult. In the present study, fullerene/metal mixtures have been vaporized using a CO₂-laser beam. The sample pellets employed in the laser vaporization were prepared from empty-cage fullerenes (C60, C70, C76, C78, C84, ..• ) and small percentages, by weight, of metal or nletal oxide (La203, SC203, Y 203, Sc, Y, Er). In addition, a sample mixture of a scandium endohedral metallofullerene extract, prepared by electric-arc vaporization, was subjected to the laser. Vaporized samples were analyzed by negative-ion chemical ionization mass spectrometry and by normal phase HPLC. Inert atmospheres of helium, argon, and xenon were compared for optimization of yields of endohedral metallofullerenes, as well as for production of unique endohedral species not observed by production via electric-arc vaporization. Scandium, yttrium, and erbium endohedral metallofullerenes were synthesized by vaporization of fullerene mixtures and the appropriate metal. Optimum conditions were realized with pellet temperatures greater than or equal to 3000°C and inert gas pressures of -100 Torr. This method of CO₂ laser vaporization also served as a valuable tool to analyze the production mechanisms of fullerenes and endohedral metallofullerenes, such as production pathways (Le., C60 -> higher fullerenes -> endohedral metallofullerenes). / Master of Science

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.

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

Advanced nuclear and electron magnetic resonance techniques (i.e. nuclear magnetic resonance (NMR), dynamic nuclear polarization (DNP), and magnetic resonance imaging (MRI)) were used to study the attitude and dynamics of TEMPO (2,2,6,6-tetramethylpiperidinyloxy)-substrate systems and the relaxivity properties of water-soluble trimetallic nitride template functionalized endohedral metallofullerenes (TNT-fMF). The attitude and average distance of interaction for each TEMPO-substrate system was determined from comparing density functional theory (DFT) calculation results with experimental hyperfine coupling constants leading to an improved understanding of solution dynamics. The short-lived solvent-solute interactions of the TEMPO-substrate molecules, such as transient complex formation, are governed by weak hydrogen-bonding interactions. The collisions in solution were explained by determining the favored orientations of the two molecules interacting using calculated relative energy minima and reproducibility of the experimental results by the calculated coupling constants. Water-soluble TNT-fMFs are studied as candidates for the next generation MRI contrast agents as diagnostic agents and also as possible therapeutic agents to kill cancer cells and decrease tumors. The TNT-fMFs are being studied as part of a multi-modal platform dependent upon which metal atoms are encapsulated inside: Gd — MRI contrast agent (diagnostic), Lu and Ho — radio labeled for use as a therapeutic agent, Tb – fluorescence, and Lu – x-ray contrast. The current commercial MRI contrast agent, OmniscanTM, contains one gadolinium atom; however, the metal is complexed to, not encapsulated in, the molecule. TNT-fMFs fully encapsulate three metal atoms to ensure the patient does not run the risk of metal poisoning. The r1 and r2 relaxivities of TNT-fMFs containing either Gd, Lu, Ho, or Sc metals were measured at 0.35T. The data for the Gd containing TNT-fMFs indicated the metallofullerene has significantly higher relaxivities than OmniscanTM, and can be the next generation MRI contrast agent. The Ho containing species has a high r2/r1 ratio compared to the other samples showing it is a potential T2 agent, and has therapeutic capabilities. / Ph. D.

A family of novel large cage Tb-based TNT-EMFs Tb₃N@C_2n (40 ≤ n ≤ 44), and a family of novel dimetallic endohedral metalloazafullerenes with the molecular formula of M₂@C₇₉N (M=Y, Tb, and La), were for the first time systematically synthesized, isolated, and structurally characterized. The protocol developed in this thesis provides an effective and systematic method for the synthesis, purification, and characterization of TNT-EMFs and other novel EMFs. Structural information about this family of Tb-based TNT-EMFs strongly supports the TNT formation mechanism of TNT-EMFs. It also demonstrates for the first time that EMFs do not necessarily choose an IPR-obeying cage even if the IPR cages are available. At room temperature and in a non-polar organic solvent, the fluorescence of the hydrogenated product of Tb₃N@C₈₀ was for the first time successfully obtained based on the proposed idea: de-shielding the screen effect of the fullerene cage on the metal ions or clusters inside the fullerene cage. The structural characterization of Tb₂@C₇₉N using single crystal X-ray diffraction crystallography demonstrated that the fullerene cage of M₂@C₇₉N is an I_h eighty-atom cage. The presence of the N atom in the molecule was further confirmed by mass spectra of the ¹⁵N labeled samples. ESR data demonstrated that there is a single-electron bond between the two Y atoms in Y₂@C₇₉N molecules. Theoretical calculations showed for the first time that the single-electron bond is low-lying at the HOMO-2 orbital and thereby resulting in a large HOMO-LUMO gap. It is, in fact, this large HOMO-LUMO gap and the low-lying single-electron orbital (hidden at HOMO-2) that are jointly responsible for the stability of M2@C79N. The single-electron bonds are the longest metal-metal bond reported so far. The chromatographic retention behavior of TNT-EMFs was also systematically studied on 5PBB and 5PYE columns. Both experimental and theoretical data demonstrated that the 5PBB column is sensitive to a fullerene's predicted cage size but indifferent to its cage symmetry, while the 5PYE column is more sensitive to the density and distribution of Ï electrons in a fullerene cage. Therefore, the 5PYE column is more suitable for separating structural isomers. The combination of the 5PBB column in the first stage and the 5PYE column in the second provides a highly effective way for isolating specific isomers. / Ph. D.

The exploitation of the relationship between the chemical and physical properties of materials is the hallmark of advancing science throughout the world. The basic understanding of how and why molecules react and interact with each other in different environments allows for the discovery and implementation of new materials and devices that not only advance the state of human life but continually change the planet. The work described in this dissertation generally falls under three diverse categories: functionalization of fullerenes, investigation of host/guest interactions in solution, and the synthesis and characterization of ion containing polymers. The separation and functionalization of fullerenes is a recent and exciting area of research. The separation methods outlined are intended to increase the availability of endohedral metallofullerenes by decreasing their cost of production. Functionalized fullerene species were achieved through Bingel and Prato reactions to provide materials with novel functional groups. These materials may be further utilized in photovoltaic or other organic electronic devices. The characterization of noncovalent interactions between different molecules in solution is the focus of supramolecular chemistry. Isothermal Titration Calorimetry stands out as one of the best, among the many methods used to elucidate the characteristics of these systems. The binding of bis- imidazolium and paraquat guests with macrocyclic host molecules has been explored in this work. The measurements of the association constants for these systems will aid in the ongoing synthesis of new host/guest systems. Ion containing polymers were synthesized and characterized for their use in electroactive devices. Imidazolium containing polymers with bulky anions were synthesized on low glass transition polymer chains. These materials had enhanced ion conductivity and may eventually be used in electronic actuator materials. / Ph. D.

Trimetallic nitride endohedral fullerenes (TNT-EMF) have been recognized for their multifunctional capabilities in biomedical applications. Functionalized gadolinium-loaded fullerenes attracted much attention as a potential new nanoplatform for next-generation magnetic resonance imaging (MRI) contrast agents, given their inherent higher 1H relaxivity than most commercial contrast agents. The fullerene cage is an extraordinarily stable species which makes it extremely unlikely to break and release the toxic Gd metal ions into the bioenvironment. In addition, radiolabeled metals could be encapsulated in this robust carbon cage to deliver therapeutic irradiation. In this dissertation, we aim to develop a series of functionalized TNT-EMFs for MRI detection of various pathological conditions, such as brain cancer, chronic osteomyelitis, and gastrointestinal (GI) tract. As a general introduction, Chapter 1 briefly introduces recent progress in developing metallofullerenes for next-generation biomedical applications. Of special interest are MRI contrast agents. Other potential biomedical applications, toxicity, stability and biodistribution of metallofullerenes are also discussed. Finally, the challenges and future outlook of using fullerene in biomedical and diagnosis applications are summarized at the end of this chapter. The large carbon surface area is ideally suited for multiple exo-functionalization approaches to modify the hydrophobic fullerene cage for a more hydrophilic bio-environment. Additionally, peptides and other agents are readily covalently attached to this nanoprobe for targeting applications. Chapter 2 presents the functionalized metallofullerenes conjugated with interleukin-13 peptide exhibits enhanced targeting of U-251 glioblastoma multiforme (GBM) cell lines and can be effectively delivered intravenously in an orthotopic GBM mouse model. Chapter 3 shows, with the specific targeting moiety, the functionalized metallofullerenes can be applied as a non-invasive imaging approach to detect and differentiate chronic post-traumatic osteomyelitis from aseptic inflammation. Fullerene is a powerful antioxidant due to delocalization of the π-electrons over the carbon cage, which can readily react with free radicals and subsequently delivers a cascade of downstream possessions in numerous biomedical applications. Chapter 4 investigates the antioxidative and anti-inflammatory properties of functionalized Gd3N@C80. This nanoplatform would hold great promise as a novel class of theranostic agent in combating oxidative stress and resolving inflammation, given their inherent MRI applications. In chapter 5, Gd3N@C80 is modified with polyethylene glycol (PEG) for working as MRI contrast agents for GI tract. The high molecular weight can prevent any appreciable absorption through the skin or mucosal tissue, and offer considerable advantages for localized agents in the GI tract. Besides the excellent contrast capability, the PEGylated-Gd3N@C80 exhibits outstanding radical scavenging ability, which can potentially eliminate the reactive oxygen species in GI tract. The biodistribution result suggests this nanoplatform can be worked as the potential contrast agent for GI tract at least for 6 hours. A novel amphiphilic Gd3N@C80 derivative is discussed in Chapter 6. It has been noticed for a long time the functionalization Gd3N@C80 contrast agents have higher relaxivity at lower concentrations. The explanation for the concentration dependency is not fully understood. In this work, the amphiphilic Gd3N@C80 derivative is used as the model to investigate the relationship between the relaxivity and concentration of the Gd-based fullerenes. Click chemistry has been extensively used in functionalization due to the high efficiency and technical simplicity of the reaction. Appendix A describes a new type of Sc3N@C80 derivative conducted by employing the click reaction. The structure of Sc3N@C80-alkynyl and Sc3N@C80- alkynyl-benzyl azide are characterized by NMR, MALDI-TOF, UV-Vis, and HPLC. The high yield of the click reaction can provide access to various derivatives which have great potential for application in medical and materials science. The functionalization and characterizations of Ho3N@C80 derivatives are reported in Appendix B. The contrast ability of Ho3N@C80 is directly compared with Gd3N@C80. The Ho-based fullerenes can be performed as the radiotherapeutic agents; the leaching study is performed to test the stability of carbon cage after irradiation. Appendix C briefly shows a new method to develop Gd3N@C80 based targeting platform, which can be used as the probe for chronic post-traumatic osteomyelitis. / PHD

Gadolinium endohedral metallofullerenes (EMFs) have shown the potential to become next generation magnetic resonance imaging (MRI) contrast agents due to their significantly improved efficiency and safety, as well as multi-day body retention which allows for a longer surgery and observation compared to current contrast agents. In Chapter 1, I have reviewed the development of gadolinium EMF based MRI contrast agents. In Chapter 2, I have described my study of Gd3N@C80 and Gd3N@C84 metallofullerenols as next generation MRI contrast agents. The metallofullerenols are synthesized and characterized utilizing UV-vis, IR, X-ray photoelectron spectroscopy (XPS) and dynamic light scattering (DLS). In addition, relaxivity data were obtained for the two metallofullerenes, and the results showed that Gd3N@C84 metallofullerenol had enhanced relaxivity compared to Gd3N@C80 metallofullerenol. This result is consistent with the observation of magnetic resonance images of the samples at different concentrations. The enhanced relaxivity was attributed to the special "egg shape" of the Gd3N@C84 cage. In Chapter 3, I have described the relaxivity study of Gd3N@C80 (without functionalization) in oleic acid, which could be used as an MRI contrast agent for more hydrophobic bioenvironments. The results show that Gd3N@C80 has a reasonable relaxation effect (relaxivity ~10 mM-1S-1 at 1.4 T) in oleic acid and could be a viable contrast agent even without functionalization. In Chapter 4, I have discussed the outlook of gadolinium EMF-based MRI contrast agents and suggested several directions for future work. / Master of Science

Der Fokus dieser Dissertation liegt auf den gemischt-metallischen Dysprosium-Nitrid-Clusterfullerenen. Durch die Inklusion von bis zu drei Lanthanoiden mit unvollständig gefüllten 4f-Orbitalen weisen diese Clusterfullerene eine Vielzahl interessanter magnetischer Eigenschaften auf. Die magnetische Charakterisierung der Nitrid-Clusterfullerene DyxSc3-xN@C80-Ih (x = 1 - 3) zeigte bereits 2014 den Einfluss der Stöchiometrie auf das magnetische Verhalten und stufte diese Verbindungen als Einzelmolekülmagnete ein. Im Rahmen dieser Arbeit wurde das Zusammenspiel zwischen den strukturellen Eigenschaften und dem magnetischen Verhalten der Clusterfullerene untersucht. Der Fokus lag auf der Synthese und der magnetischen Charakterisierung von Clusterfullerenen mit unterschiedlicher Kohlenstoffkäfiggröße bzw. -isomerie, unterschiedlicher Clusterzusammensetzung bzw. Cluster-bildender Metalle und dem Einfluss des nichtmetallischen Zentralatoms des Clusters. Die Dysprosium-Nitrid-Clusterfullerene wurden über ein modifiziertes Krätschmer-Huffman-Verfahren und unter Verwendung der trimetallischen Nitridtemplatmethode synthetisiert und anschließend mittels HPLC fraktioniert und massenspektrometrisch analysiert. Die magnetische Charakterisierung der Clusterfullerene gelang mittels DC-SQUID-Magnetometrie. Die im Rahmen dieser Arbeit untersuchten Fullerene konnten als Einzelmolekülmagnete identifiziert werden. Das magnetische Verhalten der Nitrid-Clusterfullerene wird hauptsächlich durch den Cluster M3N und weniger durch den diamagnetischen Kohlenstoffkäfig bestimmt. Jedoch wurde für DySc2N@C80-D5h und Dy2ScN@C80-D5h eine verringerte Lebensdauer der Magnetisierung im Vergleich zu ihren Analoga mit Ih-Kohlenstoffkäfigsymmetrie beobachtet. Stärkeren Einfluss hat die Kohlenstoffkäfiggröße. Für DySc2N@C68, Dy2ScN@C84 und Dy2ScN@C88 wurde eine deutliche Abnahme der Remanenz, der Blocktemperaturen und der Relaxationzeiten festgestellt. Als Ursache werden die veränderten Dy-N-Bindungslängen diskutiert. Die Clusterfullerene Dy2MN@C80-Ih und DyM2N@C80-Ih (M = Gd, Er, Lu) enthalten neben Dysprosium ein weiteres Lanthanoid im Cluster. Das zweite Lanthanoid M ruft eine erhebliche Änderungen der magnetischen Eigenschaften hervor. Die paramagnetischen Metalle Gd und Er wirken sich stark negativ auf die magnetische Remanenz aus. Für Dy2LuN@C80-Ih und DyLu2N@C80-Ih wurde ein ähnliches magnetisches Verhalten wie für DyxSc3-xN@C80-Ih (x = 1, 2) verzeichnet. Durch die Verdünnung des Fullerens DyLu2N@C80-Ih mit der diamagnetischen Verbindung Lu3N@C80-Ih wurde zusätzlich eine Erhöhung der Hysterese der Magnetisierung im untersuchten Temperaturbereich registriert. Der Einfluss der nichtmetallischen Clusterspezies auf die magnetischen Eigenschaften wurde anhand der Carbid-Clusterfullerene Dy2TiC@C80-Ih, -D5h und Dy2TiC2@C80-Ih untersucht. Obwohl die Fullerene Dy2TiC@C80-Ih bzw. -D5h sich nur durch die isoelektronische Ti-C-Clustereinheit von den Nitrid-Clusterfullerenen unterscheiden, ist deren Remanenz nur halb so groß. Ein weiteres Kohlenstoffatom im Cluster, wie in Dy2TiC2@C80-Ih, ruft eine weitere Abnahme der Hysterese der Magnetisierung hervor. Die veränderte Bindungssituation der Carbid-Cluster wird als Ursache für das beobachtete magnetische Verhalten herangezogen.