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High-quality SiOx nanoflowers have been generated by heating mixed SiC/Co powder films in a CO atmosphere. The structural features associated with different stages of the growth were monitored by SEM, TEM, EDX, and XRD analysis. A plausible mechanism for the formation of exquisite flowerlike structures is proposed in which SiC reacts with CO, the Co particles acting as a catalytic template, to yield amorphous SiOx branches. Numerous loops and branches were also observed which may arise either as a result of bifurcation or coalescence. Use of Co2O3 instead of Co as catalyst leads to abnormal flowers exhibiting secondary growth.

Novel W–Nb–S composite inorganic nanotubes have been generated by replacing W in the S–W–S sandwich layers of WS2 by Nb. The tubes are uniform, with the Nb concentration 10 atom%. Raman spectral features of the tubes are described.

Large-scale production of pure carbon spheres, with diameters from 50 nm to 1 μm, has been achieved via direct pyrolysis of a wide range of hydrocarbons, including styrene, toluene, benzene, hexane, cyclohexane and ethene, in the absence of catalyst. Specific systematic studies using styrene as the feedstock indicate that the sizes of the resulting of carbon nanospheres can be controlled quite well by adjusting the experimental conditions. The resulting materials have been fully characterized using SEM, TEM, AFM, HRTEM, EDX, elemental analysis, density measurement, XPS, FTIR, XRD, Raman, and TGA. The results show that the spheres, which are 99% carbon, consist of concentric incompletely closed graphitic shells. The dangling bonds on the edges of the shells result in high chemical reactivity.

Bioinspiration: Polar assembly (a feature of many natural protein-based fibrous structures, such as actin, microtubules, intermediate filaments, and collagens) is demonstrated in a straightforward, synthetic, peptide-based fiber system of de novo design (see false-color confocal-microscope image of fibers). This finding opens up possibilities for engineering self-assembling soft materials from the bottom up and with nano-to-microscale precision.

In this paper, a systematic study of large-scale production of highly crystalline W18O49 nanoneedles with high aspect ratios using a simple tungsten metal reacting with water at 800−1000 °C has been described. By altering the W source and other experimental conditions, we have generated W18O49 crystals with diverse morphologies, and needles with desired dimensions are achieved. The quality nanoneedles provide ideal samples for further property investigations. Possible growth mechanisms are discussed.

Current−voltage measurements of various carbon nanotube−polymer composite films at room temperature as well as at liquid nitrogen temperature reveal that the composite films consisting of defective carbon nanotubes exhibit higher conductivity than do graphite carbon nanotubes. This novel finding contradicts previous results.

Novel ceramic and carbon nanostructures have been created by thermolysis of mixtures containing polytetrafluoroethene (PTFE) and a pure metal or metal alloy in a calorimetric bomb. The influence of the stoichiometry was studied for Si-containing reactants for which the yield of the nanofibers was the highest. The process was monitored by measuring the heat of reaction and by differential thermal analysis/thermogravimetric techniques. The reaction temperatures were measured, and the heating rates of the reactants during thermal wave propagation were estimated. Elemental analysis, X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectrometry were employed to characterize the chemical composition and structural features of the products. Well-crystallized elongated single-crystal Si nanofibers, coated with a thin SiO2 amorphous layer, and crystallized carbon nanoparticles containing metals (e.g., Fe) and Si dominate. The highest yie...

The oxidation of polystyrene, polyethylene, polypropylene and poly(vinylidene fluoride) is retarded by carbon nanotubes. Incorporation of boron into the nanotubes enhances the electron affinity of the tubes and leads to a small increase in antioxidant efficiency.

One-dimensional ceramic nanostructures have been generated, employing various types of ceramic particle in a modified arc-discharge process. The influence of the filling materials on the arc discharge has been directly monitored by on-line spectroscopy. The carbon nanotube and nanoparticle yields are strongly affected by the fillings. Amorphous SiO2 and well-crystallised β-SiC nanofibres have been produced. In particular, the thin and short β-SiC nanofibres exhibit significant atom plane construction, in which the close-packed lattices are parallel to the fibre axis.

Novel binary-phase WS2−C nanotubes were generated by pyrolyzing WO3-coated multiwalled carbon nanotubes in an H2S/N2 atmosphere at 900 °C. The WS2 coating acts as an anti-oxidizing agent.

An insulated nanotube wire is formed by the binary phase of layered tungsten disulphide and carbon nanotubes (shown in the HRTEM image) generated by the sulphidization of tungsten oxide coated multiwalled carbon nanotubes at 900 °C. Thermogravimetric analysis shows that the tungsten disulphide coat acts as an antioxidant.

Ti-doped MoS2 nanotubes are produced by pyrolyzing a H2S/N2 mixture over an oxidized Ti–Mo alloy powder at elevated temperatures. Partial substitution of Mo by Ti does not significantly alter the 2H–MoS2 lattice.

Several arylfullerenes, C70Ph2n (n = 1–5), are characterised. Their electrochemical properties, investigated by cyclic voltammetry, are the result of a competition between the electron-withdrawing effect exerted by the phenyl groups and the destabilization of redox orbitals deriving from the saturation of double bonds. C70Ph2 is easier to reduce than C70, a feature possibly shared with C70Ph4 that makes these derivatives of C70 amongst the best electron acceptor molecules so far discovered. In the following derivatives, destabilization prevails, and reductions become increasingly more cathodic along the series. NMR spectroscopy is used to investigate C70Ph2n (n = 1–3). Finally, calculation of the LUMO energies supports the earlier reduction of C70Ph2 and calculations also indicate the layering of the injected charges, in the multiply-reduced species, over concentric shells. p

The main products from the reaction of C60Cl6 with fluorobenzene–FeCl3 are C60(4-FC6H4)5Cl, 1,4-(4-FC6H4)2C60 (both of Cs symmetry) and asymmetric C60(4-FC6H4)4, accompanied by a small amount of C60(4-FC6H4)4H2. Exposure of the product to light and air before processing gives other components, including C60(4-FC6H4)4(4-FC6H3)O2, C60(4-FC6H4)5OH, and C60(4-FC6H4)6 (each of Cs symmetry), C60(4-FC6H4)4O2, C60(4-FC6H4)6O2, C60(4-FC6H4)7H, and C60(4-FC6H4)5H(OH)2/C60(4-FC6H4)5H. The formation of the oxides from air-exposed reaction products emphasises the need for atmospheric protection of fullerene derivatives. Fragmentation of the oxides during EI mass spectrometry occurs readily to give C58 and derivatives which must contain adjacent pentagons, stabilisation being derived from the presence of a heptagon.

The photophysical properties of hexa-functionalized C60 derivatives (C60Cl6, C60Ph5Cl, C60Ph5H, and two C60Ph5OH isomers) have been investigated by means of UV–visible absorption and fluorescence spectroscopy in cyclohexane solution and quantum-chemical calculations derived from semiempirical Hartree–Fock approaches. A very good agreement is obtained between the measured absorption and fluorescence spectra and the calculated excitation energies, thus allowing for a detailed assignment of the optical features. The effects of symmetry and chemical nature of the functional groups on the ground-state and spectroscopic properties of the C60 derivatives are discussed.

Using a simplified in-situ process, we have successfully generated relatively long IF WS2 nanotubes, in good yield and purity. The nanotubes are formed directly from WOx nanorods created from W and SiO2 during the first stage. Structural similarities and differences between IF nanotubes and carbon nanotubes have been analyzed. A noteworthy feature of the WS2 tubes is that some of their tips are fully open.

The photophysics of six multiply phenylated C70 derivatives [C70Ph2, C70Ph4, C70Ph6 (two regioisomers), C70Ph8 and C70Ph10] have been investigated by means of steady state spectroscopy in cyclohexane solution and quantum-chemical calculations derived from semiempirical Hartree–Fock approaches. There is good agreement between the measured absorption spectra and the INDO/SCI calculated excitation energies for each derivative. The foregoing results and some additional ground state properties calculated at the AM1 level have been used to predict that the perturbation of the π electronic system of the cage results in significant changes in the photophysics of the fullerene derivatives. The effects of conjugation and spatial localization of the HOMO and LUMO orbitals on the energy of the first electronic transition are discussed in greater detail.

Nanotube research has developed rapidly over the last decade, following the bulk production of C60 and structural identification of carbon nanotubes. This review summarises achievements in nanotube and nanofibr technology, in particular, various routes to filamentous carbon and their remarkable mechanical and electrical conducting properties. These advances are paving the way to nanoscale technology and promise to provide a wide spectrum of applications.

An interesting micrometer scale tree-like structure has been generated by heating a W foil, partly covered by a SiO 2 plate, in an Ar atmosphere at ca. 1600°C. Upon sonication, the trees are broken into nanoneedles (ca. 5–50 nm wide and 20–200 nm long) and planar polyhedral nanoparticles (ca. 10–50 nm cross-section). Structural analysis, using ED, EDX, XRD, and HRTEM, showed that: (1) the trees consist of well-crystallised WO x phases ( x =0–3); (2) the nanoneedles are composed mainly of monoclinic W 18 O 49 phases; and (3) the nanoparticles consist primarily of WO 3 . The tree growth is thought to arise from the intrinsic crystalline feature of WO x , the planar defect or the shear structure of which is responsible for the breakdown of the trees.

Reaction of C60Cl6 with phenol in the presence of aq. KOH and under nitrogen, produces benzo[b]furano[2′,3′∶1,2][60]fullerene arising from substitution/elimination occurring across the 1,2-positions of the hexachloro precursor. Use of either 4-fluorophenol or 4-methoxyphenol produces the corresponding fluoro- and methoxy-substituted derivatives. Reaction with an excess of phenolic reagent results in nucleophilic replacement of some of the other chloro addends in the precursor by phenoxy groups, which may also participate in oxidative ring closure. C70Cl10 reacts with phenol in the presence of aq. KOH to give benzo[b]furano[2′,3′∶7,8][70]fullerene. The corresponding reaction of aniline with C60Cl6 produces derivatives of benzo[b]pyrrolo[2′,3′∶1,2][60]fullerene, but thiophenol does not react. Removal of eclipsing steric hindrance accounts for the ready ring-closure formation of the cycloadducts across bonds containing adjacent chlorines.

C60Cl6 Reacts with allyltrimethylsilane in the presence of TiCl4 to form a Cs symmetrical, hexaallyl addended [60]fullerene derivative, C60(CH2CHCH2)6, in 58% yield; C60(CH2CHCH2)5Cl is separated as a minor reaction product in 14% yield.

In a recent paper, Thess et al. described the formation of single wall nanotubes of a quite uniform diameter, ca. 1.36 nm, and in good yield by laser-vaporising graphite in the presence of Ni and Co. We suggest that a layer of Ni/Co atoms, adsorbed on to the surface of C60, provides a plausible catalyst template for this process.

The reaction of C70Ph8 with an excess of anthracene results in the formation of a single cycloadduct in high yield. The cycloaddition takes place across the most reactive (C48-C49) dduble bond, which is at the junction of a five- and six-membered ring adjacent to the equator.

Heating a mixture of [60]fullerene, bromine, ferric chloride and benzene under reflux for 24 h products a range of phenylated [60]fullerene derivatives. The main product is C60Ph5H but other components identified by mass spectrometry (and in some cases separated by HPLC) are: C6oPh n (n = 4, 6, 8, 10, 12), C60Ph n O2(n = 4, 6, 8, 10, 12), C60Ph n OH (n = 7, 9, 11), C60Ph n H2 (n = 4, 10), C60Ph4H4, C60Ph5H3, C60Ph n 02H (n = 5, 9), C60Ph4C6H4O2, C60Ph9OH3, and C60Ph11 O3H2. In the corresponding reaction with toluene, the crude reaction mixture contained C60(MeC6H4)4 as a main product; C60(ClC6H4)5H was obtained from the reaction with chlorobenzene. Formation of these derivatives is believed to involve radical bromination of the fullerene, followed by electrophilic substitution of the hatogenofullerene into the aromatic, accompanied in some case by hydrolysis, elimination and epoxide formation; oxidation may also introduce ketone/dioxetane functionality. The EI mass spectra of C60Ph4O2 and C60Ph8O...

Unsymmetrical C60Ph4 (1,3,11,30-tetraphenyl-1,3,11,30-tetrahydro[60]fullerene) is obtained as a minor product from the reaction of C60Cl6 with benzene–FeCl3. The formation of either this compound or the major product (C60Ph5Cl) apparently depends on the position of the initial replacement of chlorine by phenyl: substitution of chlorine at the 2-position leads to C60Ph5Cl, whereas initial substitution of chlorine at the 1-position leads to C60Ph4. A small amount of symmetrical C60Ph2 (which mechanistic considerations indicate to be the 1,4-isomer), is also obtained and is accompanied by traces of C60Ph3H3.

Pyrolysis of acetylene over quartz plates coated with various metal catalysts resulted in the formation of all-carbon nanostructures which were observed directly by scanning electron microscopy (SEM). The nanotubes were studied in detail using transmission electron microscopy (TEM), and appear to grow as ultra-thin tubes with a central hollow core and considerable thickening due to secondary pyrolytic deposition. In nearly all samples the nanotube diameter was uniform. In some cases catalytic particles were entrapped within the tubes. The efficiency of the catalysts was evaluated semi-quantitatively.

Reaction of C60Cl6 and ferric chloride with aromatic compounds gives the corresponding Cs-symmetric aryl derivatives C60Ar5Cl, where Ar = phenyl, tolyl, anisyl, tert-butylphenyl, fluorophenyl, trimethylsilylphenyl and thienyl. The derivatives arising from exclusive para substitution in anisole and fluorobenzene, together with C60(4-FC6H4)5H have been isolated and fully characterised. Toluene undergoes substitution in the ortho as well as the para position. Traces of octaaryl derivatives are obtained in the reaction with toluene and anisole. The steric bulk of the chlorofullerene (the largest electrophile known) accounts for the failure to achieve substitution in mesitylene and the abnormal deprotonation rather than desilylation in the reaction with trimethylsilylbenzene. Protiodesilylation of the trimethylsilylphenyl derivative was achieved by reaction with acid. With triphenylphosphine, C60Ar5Cl compounds react to give C60Ar5H and with toluene/FeCl3, C60Ph5Cl gives C60Ph5tolyl. C60(4-FC6H4)5H showed a marked tendency to acquire oxygen, suggesting that this oxygenation is facilitated by electron withdrawal. FAB mass spectrometry of C60(4-FC6H4)5H, C60Ph5Cl, C60Ph5H and also of C70Ph10 shows addition of up to 9C2 fragments in each case; this parallels two previous reports of C2 addition during FAB mass spectrometry. The replacement of chlorine by aryl groups at the same site indicates that frontside nucleophilic substitution on the cage must occur, involving a cationic fullerene intermediate.

In the presence of ferric chloride, benzene readily undergoes electrophilic substitution by C70Cl10 to give both yellow C70Ph10 and orange-red C70Ph8, each of which is luminescent. Their structures have been characterised by 1H and 13C NMR spectroscopy [including nOe and two-dimensional (COSY) analysis], and by UV, IR, and mass spectrometry. C70Ph10 is not formed directly from C70Cl10, but rather by further phenylation of the intermediate C70Ph8. The adjacent phenyl groups of C70Ph10 are sterically prevented from rotating at room temperature.

Recently, we have shown that [60] fullerene (C 60 ) may be produced by pyrolysis of the bowl-shaped corannulene molecule under a wide range of conditions. Both naphthalene and its dimer benzo [ k ] fluoranthene may be employed as precursors to C 60 .

Previous work on polyhydrogenation of fullerenes leading to C 60 H 36 and C 70 H 36 as the main products is reviewed. The most probable structures of these species, based on their aromaticities, are presented. Zinc/concentrated HCl is shown to be an excellent and rapid reducing agent for benzene or toluene solutions of fullerenes at room temperature. The polyhydrogenated species are unstable towards light and undergo oxidative degradation, with, in the case of C 60 H 36 , formation of C 60 H 18 as an intermediate. Reduction of these fullerenes by zinc/concentrated DCl gives C 60 H 44 and C 70 H 48 as the highest hydrogenated products; the greater incorporation of deuterium is attributed to the greater C-D bond energy. In the absence of light and oxygen, C 60 H 36 exhibits high thermal stability. Attempted further reduction of C 60 H 36 leads to formation of trimethylene adducts; these are also formed on reduction of [84] fullerenes which gives C 84 H 48 as the main product.

[60]Fullerene is produced by pyrolysis of corannulene between 650 and 1200 °C, (either with or without the presence of Pd/C or Co catalysts), 7, 10- bis(2,2′ -dibromovinyl)fluoranthene (a corannulene precursor) at 700 °C, and of 11, 12-benzofluoranthene at 900–1000 °C.

Block polymers of methyl methacrylate and methacrylic acid have been prepared using the technique of enolate-initiated anionic polymerisation, employing trimethylsilyl methacrylate as a precursor for the methacrylic acid component. The structure of the product has been characterised by infra-red and NMR spectroscopy, and by thermogravimetric analysis.

[60]Fullerene reacts with neat triethylamine via an electron transfer involving an intermediate C60-radical-anion, to give a salt-like product. This decomposes to [60]fullerene upon either heating, or treatment with ultrasound. EI mass fragmentation of the product indicates an intramolecular abstraction of H from C2H5 by the [60]fullerene moiety.

A novel crystalline compound has been made by combining the two elements, carbon and phosphorus, that form isolated cage allotropes. The material, C 60 (P 4 ) 2 , which consists of disordered tetrahedral P 4 molecules intercalated in a hexagonal C 60 crystal lattice has been prepared by both gas—solid reaction and co-precipitation from benzene solution.

Aligned carbon nanofibers/tubes, ca. 20-50 nm in diameter, were generated by hollow cathode glow discharge decomposition of Fe(C 5 H 5 ) 2 in He at ca. 200 °C on an Al 2 O 3 membrane. The as-deposited product consists of bundles of amorphous carbon nanofibers with numerous Fe nanoparticles embedded therein. Heating at 1100 °C under Ar produced well-crystallized carbon nanotubes.

Removal of the carbon template from WS2-coated multi-walled carbon nanotube (MWCN) composites, produced WS2 nanotubes with intriguing microstructures. TEM characterisation shows that the intermediate phases of amorphous WO3−x-WS2 nanostructures, support the previously proposed growth model for WS2 nanotubes on MWCNs.

THE formation of bulk quantities of C60 by arc discharge between carbon electrodes in an atmosphere of helium1 or argon2,3 has led to an explosion in fullerene research. Methods for improving the rate of fullerene production have included increasing the reactor size and the diameter of the carbon rods, and varying the rate of rod consumption and helium pressure4. Systems using several rods have also been employed5,6. The ideal method, however, would involve a continuous process that does not require rod replacement. Approaches using carbon granules6 and powders7 have been reported, as well as combustion methods using hydrocarbons8,9. Here we report the formation of C60 and C70 by pyrolysis of naphthalene at ∼1,000 °C. C60 and C70 are formed by the 'patching together' of six and seven naphthalene molecules respectively, as demonstrated by mass-spectrometric analysis of intermediate products. These results point to a continuous method of fullerene formation, and also show that closed fullerene cages can be built from well defined aromatic fragments.

Carbon disulphide is rapidly converted into sulphur by C60 deposited on neutral alumina, through formation of hydrogen sulphide which is then oxidised. C60 is more effective than graphite in this oxidation, which also occurs (though more slowly) in the absence of alumina. It is therefore essential to remove all traces of carbon disulphide traces when purifying C60 by column chromatography of soot extract deposited from carbon disulphide solutions.

Recent developments in experiment and theory have enhanced our understanding of fullerene stability and reactivity to the point where predictions may be made concerning the probable existence of specific fullerenes and their derivatives. One approach, considered here for small fullerenes (Cn, n

Analysis of the Raman spectra of three brominated fullerenes, obtained at 1 cm−1 resolution, provides supporting evidence for the structural models derived from X-ray single crystal studies. The measured Raman frequencies can be rationalized on the basis of symmetry considerations.

The chemistry of buckminsterfullerene (C60) is in its infancy and an understanding of the principles for the preparation of pure C60 derivatives of known addition pattern and C60 materials of known composition is necessary for its development. Single crystal X-ray diffraction is a powerful tool for the determination of the structures of C60 compounds, five examples of which are described here. C60 is brominated by Br2 in a variety of solvents to give either C60Br6 or C60Br8, depending upon the particular solvent used. Crystals of C60Br6.Br2.CCl4 (1), C60Br6.2Br2 (2), and C60Br8.2Br2 (3) were obtained from CCl4, C6H6, and CS2 respectively. Slow evaporation of C6H6 solutions of C60 gives crystals of C60.4C6H6 (4). Mixing of saturated C6H6 solutions of C60 and ferrocene gives a dark red solution from which crystals of C60.2ferrocene (5) are deposited.

Using high pressure liquid chromatography, the fullerenes C76, C78. C84, and C86–C102 have been separated (in some cases partially) from soot produced by the arc-discharge procedure. The 13C NMR spectrum for C76 confirms that reported previously, whilst the spectrum for C78 indicates the presence of C2v, D3, C2v, isomers in the approximate relative yields (there is a small batch dependence) of 52 : 30 : 18%. The spectrum for the D3 isomer (confirmed from two separate batches) differs from that given in the literature with respect to the location of one peak. The relative peak heights in the C8413C NMR spectrum are similar to those reported for samples produced under different conditions. The stabilities of the component isomers must therefore be similar and so produced in a similar ratio irrespective of conditions; this indicates them to be the D2and a O2d isomers. The spectrum also contains over 70 minor peaks due to other isomers of C84. Eleven of the peaks are more intense than the others, consistent with the presence of the D3d and D6h isomers, predicted to be of relatively high stability. Two fractions (giving yellow solutions in hexane) eluted after C84: the first was separated into two components, shown by mass spectrometry to consist of minor amounts of C86–C92, and mainly C90 and C92 with lesser amounts of C94–C,102, respectively. The 13C NMR spectrum of the C94–C102 component indicated the presence of a fullerene isomer of high symmetry. The second yellow fraction consisted largely of C82 together with traces of fullerenes up to C108, but the quantity was insufficient for the 13C NMR spectrum to be obtained. The retention time of C82 is inconsistent with values for the other fullerenes indicating that it consists of the C3v isomer, predicted to be polar. C90 eluted with two different retention times suggesting that the second fraction is also a polar isomer. One sample of C84 contained a coeluent, identified by mass spectrometry as C70H12; proposals are made concerning its possible origin, structure, and stability relative to other hydrogenated derivatives.

Extension of the chromatographic work that led to the first isolation of pure Go and 00 has resulted h the isolation and characterisation of c76 and three isomers of c78. Comparison with other work indicates the composition ratio of c78 to be dependent upon the method of chon production. Halogenation of Go gives derivatives that have been charactwised either by NMR, or by single aystal X-ray diffraction. The halogeno derivatives readily undergo nucleophilic substitution, which provides a route to the formation of many fullerene compounds, but precludes use of the fluoro derivatives as lubricants. In the presence of Friedel-Crafts catalysts, the bromo derivatives substitute into aromatics to give aryl derivatives of Go, especially those containing either 6, 8, 12, or 16 aryl groups per C6o molecule. Possible structures for these are compared with those for addition products which have only low eclipsing steric interactions.

The synthesis of branched poly(methyl methacrylate) is described. The method used is based on an anionic technique with initiation by enolate ions. details of product characterization are included.

Isocyanatoethyne, HCCNCO, has been prepared and its microwave spectrum recorded. The molecule behaves as a slightly asymmetric prolate rotor, the spectrum indicating deviations from linearity in the equilibrium structure. Vibrationally excited states with up to three quanta of the CNC bending mode were observed, allowing analysis of the spectrum to be carried out using a semirigid bender model. The results of this analysis give the following structural parameters: r(CC) = 1.2237 (20) A , r(CN) = 1.3025 (54) A , r(NC) = 1.2139 (60) A , r(CO) = 1.1741 (48) A , ∠(CNC) = 140.67 (48)° and, ∠(NCO) = 170.02 (93)°, with all other bond angles assumed to be 180°. The barrier to linearity was calculated to be 537.2(5.4) cm−1.

The chromatographic procedure which led to isolation of the first pure samples of C60 and C70, together with recent advances in the separation of higher fullerenes, are described. At least three isomers of C78 exist. Structural features contributing to the stability differences between fullerenes are discussed. 13C NMR, UV, IR, Raman and neutron scattering/diffraction measurements on C60 and C70 are summarized and reviewed.