SYNTHESIS,CHARACTERIZATION, AND BIOLOGICAL PROPERTIES OF A FULLERENE TRIPHENYLPHOSPHONIUM SALT

A monofunctionalised fullerene triphenylphosphonium salt has been synthesised to investigate the potential for adaptation of fullerenes for biological application. The redox properties of fullerenes make them effective radical scavengers and consequently they are potential antioxidants in biological systems The triphenylphosphonium moiety was chosen because this lipophilic cation increases both the solubility and membrane permeability of attached compounds, and has been used as a delivery agent in biological systems in other contexts. Furthermore, the triphenylphosphonium moiety binds tightly to cognate antibodies, facilitating linkage of attached molecules to proteins. Here we report on the interaction of a triphenylphosphonium fullerene salt with biological systems and its binding of antibodies against the triphenylphosponium moiety.     

Grafting of buckminsterfullerene onto polythiophene: novel intramolecular donor-acceptor polymers

Conjugated polymer-fullerene composites have shown efficient photoinduced charge transfer. The attachment of a fullerene moiety to the conducting polymer backbone is expected to lead to materials with more intimate association of the donor/acceptor sites. Two approaches to the attachment of fullerenes onto polythiophene derivatives have been explored. In the first case, fullerene has been bonded to a bithiophene derivative which can be electropolymerized. In the second, solvent processable polythiophene copolymers were prepared and functionalized with fullerene. Both these systems exhibit electrochemical and optoelectrochemical properties for fullerene and the conducting polymer.     

Fullerenes and Viruses

Abstract

It is well known that any, sometimes very small, changes in the chemical structure can lead to the dramatic changes in biological properties. Therefore it is necessary to divide into two different topics the studies of biological properties of fullerene and fullerene‐like compounds. In the enormous variety of data on the biological activity of fullerenes it is possible to select some with defined mechanism of action. This selection showed that in case of using the fullerene‐containing compositions the main mechanisms of drug action, namely unspecific, specific (ligand–receptor) interaction and membranotropic can be obtained. Therefore fullerenes as compounds with broad biological potential are very promising not only for the design of antiviral compounds, but also for the design of various types of drugs.     

纳米富勒烯颗粒水悬液的制备与生物学效应

富勒烯以其独特的物理化学性质吸引了众多研究者的关注.但富勒烯在水中的溶解度十分有限,成为其应用在生物系统中的瓶颈.最近发现,将富勒烯制备成纳米颗粒水悬液是一种能有效改善富勒烯水溶性的方法.介绍了目前采用的4种制备方法,即四氢呋喃-丙酮法、甲苯超声法、四氢呋喃法、直接搅拌法,同时还介绍了水中纳米富勒烯颗粒可能形成的机制以及纳米富勒烯颗粒的细胞毒性和抗菌活性等方面的研究进展.     

Modeling the structure of fulleranes and their endohedral complexes involving small molecules with nontrivial topological properties

'In' and 'out' isomers of perhydrogenated fullerenes and endohedral fullerene complexes have only recently been incorporated into the realm of topological chemistry. The 'in' isomers are, until now, purely hypothetical while for the latter group mostly studied are the complexes with metal ions that can be obtained during the fullerenes manufacturing. Much more difficult to obtain are the complexes with small molecules buried inside fullerene cages produced by laborious synthesis involving opening the cage, inserting the guest into it, and closing the cage chemically. This complicated procedure has only recently been accomplished for a hydrogen molecule put in the C60. Two H2 molecules inside the opened C70 cage and H2O in the opened C60 have been also reported recently. Model calculations, when carefully applied, allow one to predict the possibility of obtaining endohedral fullerene complexes with small molecules and 'in' isomers of perhydrogenated fullerenes. However, such systems are too large to be reliably handled by quantum calculations. Interestingly, such a simple method as molecular mechanics seems much more trustworthy.     

Fullerene Research at the University of New South Wales

This paper gives an overview of our group's involvement in fullerene research which has been focussed in the two areas of mass spectrometry and production of fullerenes. The early work was mainly concentrated on the observation of fullerene ions in laser ablation mass spectrometry. We have also tried to develop other carbon sources of fullerenes besides graphite. The fullerene work continues and has led us into other areas such as the study of the reactivity of small carbon anions.     

Fullerene Research at the University of New South Wales

Abstract

This paper gives an overview of our group's involvement in fullerene research which has been focussed in the two areas of mass spectrometry and production of fullerenes. The early work was mainly concentrated on the observation of fullerene ions in laser ablation mass spectrometry. We have also tried to develop other carbon sources of fullerenes besides graphite. The fullerene work continues and has led us into other areas such as the study of the reactivity of small carbon anions.     

Moving pentagons on nanocones

Abstract

Fullerenes are made by the intersection of twelve pentagonal nanocones. This note deals with an innovative isomeric mechanism, based on a sequence of Stone-Wales rotations, for moving the pentagonal face on the cusp of the nanocone. The modified nanocone is the seed for creating new fullerenes with different symmetry and size. Present results may help to model fullerene formation and, on the pure algorithmic side, may contribute to evolve the computer tools that generate fullerenes. This mechanism may also find application in mimicking the behaviors of biological systems that, like many viruses, are also describable in terms of spherical cages tiled by polygons.     

The Formation of Fullerenes from Sonic Velocity Gaseous Carbon

A contact are and adiabatic expansion hybrid reactor has been utilized to provide a controlled cooling process of gaseous carbon species capable of attaining very high velocities. Both vaporization and annealing temperatures and annealing time were found to be impartant for the formation of fullerenes. Immediate rapid quenching of gaseous carbon resulted in the reduction of fullerene yields. However, rapid quenching was demonstrated to improve the fullerene yield by preserving the as-grown fullerenes in the high temperature annealing process.     

Fullerene Production in Tons and More: From Science to Industry

In the last decade, application of fullerenes has been proposed actively in a wide range of areas, and recent developments suggest that many of those applications are to be practical technologies. However, there has been no large-scale production enterprise for commercial usage of fullerenes. High production cost and limited availability of fullerenes have been the main obstacle in the development of the Fullerene Market. Improved flame-based technology leads to the most feasible process for mass production of fullerenes, since it is a continuous process and uses inexpensive hydrocarbons as its starting materials. In May 2003, we started fullerene production in tons and more to supply fullerenes with reasonable price as practical materials for industries.     

Interaction between fullerenes and single-wall carbon nanotubes: the influence of fullerene size and electronic structure

A series of fullerenes and endohedral metallofullerenes peapods have been synthesized by supercritical method in high filling rate. The interaction between SWNTs and various kinds of fullerenes (C60, C70, C78, C84) and metallofullerenes (Gd@C82, Er@C82, Ho@C82, Y@C82) has been further investigated. The slight blue shift of G-band in Raman spectra with respect to pristine SWNTs was attributed to the charge transfer from SWNTs to fullerenes cage. The obvious RBM shift strongly depended on the distance between the inner wall of the SWNTs and the fullerene cage and also partly associated with the electronic structure of the fullerene. These results indicated that the interaction between fullerenes and SWNTs, which was considered to be the van de walls interaction, can be influenced by the cage size and the kind of fullerenes.     

Optical,structural and electrical properties of polyaniline systems doped with C60 and small gap C60 fullerenes

In this work two systems consisting on polyaniline (Pani) doped with simple and small gap C₆₀ fullerenes have been prepared and characterized. Composites with different doping amounts of 1,2,4 and 8 wt% have been analyzed in order to evaluate their structure together with their optical and electrical properties and the effect of fullerene type and amount on them. The shift and change of shape in Fourier transform infrared spectroscopy (FTIR) bands and solid ¹³C NMR spectroscopy signals showed the presence of interactions between matrix and fullerenes by electron density transfer among them. Optical properties have also been analyzed in terms of ultraviolet (UV) spectroscopy. The blue shift of several bands confirmed the charge transfer. Obtained structures have been analyzed by optical microscopy (OM) showing the different way in which both types of fullerenes have been incorporated into the polymer chains. Finally, conductivity has been measured by the four probe technique, relating obtained values with the structure of the composite and the different degree of crystallinity of simple and small gap fullerenes.     

Synthesis and Laser Desorption Fourier Transform Mass Spectrometry of Massive Fullerenes

Synthesis of buckminsterfullerene (C₆₀) is highly simple and the mechanism of the molecule formation is quite well understood. It makes easier the search for the optimum conditions necessary for formation of massive fullerenes (more than 100 carbon atoms). The most popular graphite arc method has been used for fullerene synthesis in our laboratories. Other available methods, like laser ablation and E-gun evaporation, were not suitable for achieving of the convenient conditions. Results of the synthesis have been analyzed by laser desorption Fourier transform ion cyclotron resonance mass spectrometry (LD FT/ICR-MS).

The conditions for massive fullerenes synthesis are discussed in the paper. The special care has been given to the LD FT/ICR-MS analysis. The importance of cooling gas during fullerene nucleation and growth in the very specific vacuum conditions is analyzed. The necessity for a thorough dynamic plasma diagnostic during the giant fullerenes growth is suggested.     

A STUDY ON THE THERMAL STABILITY TO 1000°C OF VARIOUS CARBON ALLOTROPES AND CARBONACEOUS MATTER BOTH UNDER NITROGEN AND IN AIR

The thermal behavior of graphite, C₆₀ fullerene, fullerene black (carbon soot containing fullerenes), extracted fullerene black and diamond has been analyzed to 1000°C by TGA-DTA (thermogravimetric analysis and differential thermal analysis) under a nitrogen flow at a heating rate of 20°C/min. Very small weight losses have been recorded in the case of graphite and diamond. Furthermore no diamond graphitization has been observed. The sublimation of pure C₆₀ and the fullerene fraction of fullerene black (both pristine and extracted) has been observed and discussed.

The combustion reaction in air flow of graphite, C₆₀ and C₇₀ fullerenes, fullerene black (both unextracted and extracted), carbon nanotubes and diamond has been studied by TGA-DTA at a heating rate of 20°C/min. C₇₀ fullerene and fullerene black have been found to be the most reactive carbon materials with O₂. The role played by C₇₀ in the degradation of fullerites has been discussed. Among the carbon materials examined, the best resistance to O₂ attack has been shown by diamond and carbon nanotubes. The behavior of graphite is intermediate between diamond and fullerene blacks. The behavior of C₆₀ fullerene appears closer to that of graphite although it appears to be more reactive with O₂. Samples of graphite and carbon blacks N375 and N234 have been studied by TGA-DTA in air flow before and after a radiation treatment with neutrons or γ radiation. The effect of the radiation damage in the combustion reaction of these carbon materials has been discussed.     

Charged fullerenes as high-capacity hydrogen storage media

Using first-principles calculations within density functional theory, we explore systematically the capacity of charged carbon fullerenes Cn (20 相似文献   

The Formation of Fullerenes from Sonic Velocity Gaseous Carbon

Abstract

A contact are and adiabatic expansion hybrid reactor has been utilized to provide a controlled cooling process of gaseous carbon species capable of attaining very high velocities. Both vaporization and annealing temperatures and annealing time were found to be impartant for the formation of fullerenes. Immediate rapid quenching of gaseous carbon resulted in the reduction of fullerene yields. However, rapid quenching was demonstrated to improve the fullerene yield by preserving the as-grown fullerenes in the high temperature annealing process.     

Predictions of novel nanostructures of silicon by metal encapsulation

Recent studies using ab initio total energy calculations have shown exciting possibilities of developing novel metal encapsulated caged clusters of silicon with fullerene-like, Frank–Kasper and other polyhedral structures. In contrast to carbon for which empty cage fullerene structures are stable with 20 or more atoms, 10–16 atom silicon cage structures are stabilized by a guest metal atom. These nanoclusters are predicted to exhibit luminescence in the visible range and could find applications in biological systems, optoelectronics, and as tagging material. The Raman and infrared spectra have been calculated and they could help in the experimental identification of the structures. Interaction of these clusters with metal as well as oxygen or hydrogen atoms show that the fullerene structure is stable. Also the interaction between clusters themselves is weak and the ionization potentials, large. These properties make them attractive for cluster assembled materials such as nanowires, nanotubes, and other 2 and 3D structures. Studies on hydrogen interaction have led to the predictions of empty center hydrogenated silicon fullerenes Si_nH_n with large HOMO–LUMO gaps. These could further be doped endohedrally or exohedrally to produce novel silicon fullerenes with a variety of properties opening new ways of using silicon for diverse applications.     

Thin fullerene-containing films synthesized by ion beam sputtering of fullerene mixtures with doping additives in vacuum

A new approach to the synthesis of films containing fullerenes and doping elements is described. It is suggested that a cluster mechanism of the target sputtering by accelerated ions makes possible the deposition of fullerenes on a substrate with a certain probability for dopant atoms being introduced into the cavities of fullerene molecules and a higher probability of their occurrence between fullerene molecules. The proposed method has been experimentally implemented by using an Ar⁺ ion beam to sputter C₆₀/C₇₀ fullerene mixtures (synthesized in a plasmachemical reactor at a pressure of 10⁵ Pa) pressed into disk targets with a doping element (Fe, Na, B, Gd, or Se). The ion beam sputtering of dopant-containing fullerene mixtures in a vacuum of ～10^?2 Pa allowed micron-thick films containing C₆₀ and C₇₀ fullerenes and the corresponding dopant element (Fe, Na, B, Gd, or Se) to be grown on quartz substrates.     

Translocation of C60 and its derivatives across a lipid bilayer

Obtaining an understanding, at the atomic level, of the interaction of nanomaterials with biological systems has recently become an issue of great research interest. Here we report on the molecular dynamics study of the translocation of fullerene C60 and its derivative C60(OH)20 across a model cell membrane (dipalmitoylphosphatidylcholine or DPPC bilayer). The simulation results indicate that, although a pristine C60 molecule can readily "jump" into the bilayer and translocate the membrane within a few milliseconds, the C60(OH)20 molecule can barely penetrate the bilayer. Indeed, the mean translocation time via diffusion for the C60(OH)20 molecule is several orders of magnitude longer than for the former. It was also determined that the two different forms of fullerenes, when adsorbed into/onto the bilayer, affected the membrane structure differently. This study offers a mechanistic explanation of that difference and for the reduced acute toxicity of functionalized fullerenes.     

Buckybowlsynthesis: A Novel Application of Flash Vacuum Pyrolysis

This review outlines our contribution to the field of fullerene fragments by the Flasn Vacuum Pyrolysis (FVP) of polycyclic aromatic hydrocarbons. The importance of partially fluorinated polycyclics as potential precursors to fullerene fragments and fullerenes is exemplified.