Amphiphilic fullerene derivatives, which have a carbonaceous structure as a hydrophobic part of the molecule, have shown a wide range of physical and chemical properties that make them attractive for the preparation of supramolecular assemblies and new materials. Thus, methods for preparation of assembled materials as well as methods of synthesis of amphiphilic fullerenes are currently drawing much scientific interest. In this thesis, I report that fullerene vesicles can be transformed into a two-dimensional material. Besides, I have developed a new method for the synthesis of hydrophosphorylated fullerenes by mixing [60]fullerene (C60) in a mixed solvent. These hydrophosphorylated fullerenes become fullerene amphiphiles after basification. The contents of each chapter of this thesis are summarized below.

In chapter 1, the backgroLind of fullerene amphilphiles is described. Fullerene amphiphiles have a carbonaceous structure as a hydrophobic part and functional group(s) as a hydrophilic part of the molecule. The approaches of fullerene amphiphiles are on introduction of hydrophilic function(s) by chemical modification of C60 through two main pathways: nucleophilic additions, and cycloadditions. When fullerene amphiphilies dissolve into water, they form supramolecular aggregates. The formations of supramolecular assemblies include rods, tubes, vesicles, and films.

Chapter 2 describes that the fullerene bilayer vesicle can be transformed to thin film under appropriate conditions. Our group discovered that an amphiphilic fullerene, fullerene cyclopentadienide (Fig. 1), spontaneously forms a spherical bilayer vesicle when the molecules are dissolved in water. The vesicle has a bilayer membrane where the molecules are stacked in a head-to- head fashion, and is expected to be an ideal precursor for assembled materials of other morphologies. Fullerene thin films are obtained by freezing this fullerene vesicle solution. Transmission Electron Microscopy (TEM) image reveals flat plane supramolecular structures (Fig. 2), which size ranges from several hundred to over one thousand nanometer. Structural studies on the thin film by TEM show that the thin film is composed of the crystalline membrane of amphiphilic fullerene. The packing parameters of thin films suggest hexagonal packing with AB stacking of the layers.

The morphological change of vesicle was related to the concentration of THF. The Dynamic Light Scattering (DLS) analysis of a size change of vesicle in the volume of 30% THF showed that the size of the particles increase gradually for the first one hour; after two hours of mixing, the distribution of the particles became bimodal, and the size of the larger particles precipitously were over 800 nm at this time; the distribution of the larger particles finally increased to 1200 nm. The change in the particle size accompanied the change in the morphology. Atomic Force Microscope (AFM) images showed that the particles retained the spherical form for the first one hour; however, the particles I observed after eight hours were mainly thin films. Both DLS studies and AFM images on the thin film formation 、vere concluded a plausible mechanism: upon increasing the amount of THF, the molecLIie intercalates in the fullerene membrane; by absorbing the small molecule, the fullerene membrane gains the fluidity and vesicles start to fuse to grow in size, and start to collapse to give the thin film finally. The particle shape analysis indicated that the thin films was formed in solution, and supported by themselves.

In chapter 3, the synthesis of hydrophosphorylated fullerene in neutral conditions is shown. The amphiphilic fullerene bearing phosphorous groups has great potential in bioactive system. However, the methodology of fullerene phosphorous compound is quite rare. Recently, our group reported oxoamination reaction of C60 which promote by dimethylsulfoxide (DMSO). Following this lead, we gain a simple access to phosphorous fullerene derivatives. The synthesis of hydrophosphorylated C60 achieved just by mixing equimolar of C60 and secondary phosphine oxide in 20% DMSO/clorobenzene (C6H5Cl) without extraneous reagents in moderate to good yield (Eq 1). It undergoes a 1,2-addition addition to give fullerene-substituted phosphine oxide. The procedure is very simple and the synthesis can be carried out on a gram scale. The phosphorous oxides include dialkyl, alkylaryl, and diaryl phosphine oxides bearing alkoxy-, bulky alkyl- and fluorosubstituents. The use of excess phosphorous reagent or longer reaction time does not improve the yield because of the formation of multiadducts. We also obtained fullerene-substituted phosphine by mixing a Ph2PH and C60 in 20% DMSO/ C6H5Cl. This product, however, is exceedingly sensitive to oxidation in air owing to the photoactivity of the fullerene moiety, and isolated as the corresponding phosphine oxide

Not only DMSO promotes the hydrophosphorylation of fullerene, but also hexamethylphosphoramide (HMPA) and N,A^dimethylformamide (DMF) accelerates the reaction. No reaction takes place in the absence of DMSO and lOO% of C60 is recovered. The role of C6H5Cl is just to dissolve C60 The reaction rate is in an order of DMF < DMSO < HMPA, which follows that of the donor number of each solvent. This order is similarly to the oxoamination and reduction of C60. The key role of DMSO suggests that the reaction takes place through a charge transfer or an electron transfer complex by interaction between phosphine and C60. The complex then undergoes C-P bond formation to generate a diradical intermediate. Rapid isomerization of the diradical intermediate to finally produces the product. In phosphine oxide case, tautomerization should be considered. The reaction takes place via a hydroxyl phosphine form rather than the phosphine oxide form.

Accordingly, hydrophosphorylation of fullerene is run under neutral conditions, the tolerance of functional groups is high, and a variety of phosphorous fullerene could be synthesized. Phosphinate and phosphonate are less reactive and does not undergo the hydrophosphorylation reaction under room temperature as the one used for phosphine oxide. However, both phosphinate and phosphonate reacted with C60 at higher temperature in presence of excess amount of phosphorous nucleophiles.

The hydrophosphorylated fullerenes are precursors of fullerene amphiphiles. Basification of hydrophosphorylate fullerene can generate the corresponding phosphorylated fullerene anion (Fig. 3).Dilution of the THF solution of with water forms a stable homogeneous solution. This aqueous solution has the characteristic UV/VIS/NIR spectra with a broad peak in the visible region, which was attributed to aggregation of fullerene in water.

In chapter 4, I summarized the all results including the transformation of fullerene vesicles into thin films and synthesis of fullerene amphiphihes beanng phosphorous moiety. I also have an outlook for the application of fullerene amphiphiles in materials and bioactivity.

Figure 2. TEM images of fullerene thin films

本論文は，4章から構成されており，両親媒性フラーレンの合成と超分子集合体の開発研究について述べられている．

第1章では，両親媒性フラーレンの形成する超分子集合体について，これまでの具体的研究例を挙げ，その重要性について述べられている．

第2章では，両親媒性フラーレンの自立型分子薄膜の調製方法の開発について述べられている．この研究では，両親媒性フラーレンであるフラーレンシクロペンタジエンの二重膜ベシクルを前駆体とすることで界面を必要としない自立型分子薄膜を調製した．自立型分子薄膜の透過型電子顕微鏡による構造解析により，最密充填膜がAB周期により重なった結晶膜であることを明らかにした．また，レーザー光散乱法により薄膜生成の過程の分析を行い，二重膜ベシクルが溶液中で融合，破裂することで自立型分子薄膜が得られることを見いだした．さらにフロー式粒子像分析装置による分析により，溶液中で自立型分子薄膜が生成することを確認した．これまでフラーレン薄膜の調製法としてはラングミュア・ブロジェット法や自己組織化膜法などが利用され，基板となる界面を必要としていた．この研究で見いだされた自立型分子薄膜の調製法は，基板を必要としないことから，今後，フラーレン分子薄膜を利用した機能性物質の合成法として展開されることが期待される．またこの研究では，種々の構造分析手法を有機的に組み合わせることで，本来構造解析が困難なナノメートルサイズの物質の構造を明らかにしたことも特筆に値する．

第3章では，ヒドロホスフォリル化フラーレンの合成反応の開発について述べられている．リンを含む官能基は，両親媒性分子の親水性官能基として広く天然に見いだされる官能基である．しかし，フラーレンに含リン官能基を導入する手法は，これまで数少なく，さらに親水性の高い含リン官能基を導入することは困難であった．この研究では，ジメチルスルホキシドを補溶媒とすることで，中性条件下，リン化合物のC60への付加反応が良好に進行することを見いだした．本反応ではリン化合物としては第2級ホスフィン，ホスフィンオキシド，ホスフィン酸誘導体やホスフォン酸誘導体などさまざまな化合物が反応活性であることが見いだされ，種々の置換基をもつヒドロホスフォリル化フラーレンを合成した．この研究では，いくつかの補溶媒について検討が行われ，電荷移動を経た反応機構が提唱されている．またこの合成手法は多種多様な置換基を許容し，ヌクレオシドをもつヒドロホスフォリル化フラーレンの合成に成功している．この研究では，さらにヒドロホスフォリル化フラーレンを利用し，水中分子集合体の構築についても検討が行われている．

第4章では，本論文の総括と今後の展望が述べられている．

なお，本論文第2章は，磯部寛之氏，中村栄一氏，安永卓夫氏，若林健之氏との共同実験，第3章は，磯部寛之氏，ニクラスソリン氏，中村栄一氏との共同実験であるが，論文提出者が主体となって検討を行ったもので，論文提出者の寄与が十分であると判断する．

本研究は両親媒性フラーレンの自立型薄膜集合体の合成および新規両親媒性骨格をもつヒドロホスフォリル化フラーレンの簡便な合成手法の開発に成功し，炭素クラスターを利用する超分子化学や材料化学分野に多くの知見を与えた．したがって，本論文は博士（理学）を授与できる学位論文として価値のあるものと認める．