CARBON nanotubes1 are expected to have a wide variety of interesting properties. Capillarity in open tubes has already been demonstrated2–5, while predictions regarding their electronic structure6–8 and mechanical strength9 remain to be tested. To examine the properties of these structures, one needs tubes with well defined morphologies, length, thickness and a number of concentric shells; but the normal carbon-arc synthesis10,11 yields a range of tube types. In particular, most calculations have been concerned with single-shell tubes, whereas the carbon-arc synthesis produces almost entirely multi-shell tubes. Here we report the synthesis of abundant single-shell tubes with diameters of about one nanometre. Whereas the multi-shell nanotubes are formed on the carbon cathode, these single-shell tubes grow in the gas phase. Electron diffraction from a single tube allows us to confirm the helical arrangement of carbon hexagons deduced previously for multi-shell tubes1.

Single-shell carbon nanotubes of 1-nm diameter

The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.

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Carbon Nanotubes: Present and Future Commercial Applications

Nanoparticles — particles in the size range 1–100 nm — are emerging as a class of therapeutics for cancer. Early clinical results suggest that nanoparticle therapeutics can
show enhanced efficacy, while simultaneously reducing side effects, owing to properties such as more targeted localization in tumours and active cellular uptake. Here, we
highlight the features of nanoparticle therapeutics that distinguish them from previous anticancer therapies, and describe how these features provide the potential for
therapeutic effects that are not achievable with other modalities. While large numbers of preclinical studies have been published, the emphasis here is placed on preclinical and clinical studies that are likely to affect clinical investigations and their implications for advancing the treatment of patients with cancer.

Nanoparticle therapeutics: an emerging treatment modality for cancer

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Applications of nanocomposites

A comparative study of the influence of Co (or Ni) promoter loadings and the effect of different sulfurizing agents and sulfurizing temperatures on the structure, morphology and catalytic performance of Mo- or W-based hydrodesulfurization (HDS) catalysts was carried out. Catalyst performance using a tubular fixed-bed reactor and the HDS of thiophene as a model reaction was evaluated. The oxidic and sulfurized states of the HDS catalysts were characterized by laser Raman spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and high resolution transmission electron microscopy (HRTEM). It has been found that the urea-matrix combustion (UMxC) synthesis is a simple tool for preparing supported catalysts in a short period of thermal treatment. Several consecutive stages such as urea melting, metal precursor dissolution and chemical reactions take place before and upon combustion process. The C4H4S/H2-activated Co- (or Ni-) promoted MoS2 (or WS2) catalysts present a strong synergistic effect (SE) when the Co (or Ni)/Mo (or W) molar ratio is near to 0.5, whereas the C4/C
 4
 =
 molar ratios display a weak antagonistic effect. Alumina-supported Ni–W catalyst showed an optimal SE 2.5 times higher than those for Co (or Ni)-promoted Mo HDS catalysts. The kinetic parameters for thiophene-HDS reaction were also determined, suggesting that the C–S bond cleavage reaction for alumina-supported Co(Ni)–Mo HDS catalysts and H2 activation reaction for Ni-promoted WS2catalysts play an important role in the rate-limiting step.

Rationalizing the catalytic performance of γ-alumina-supported Co(Ni)–Mo(W) HDS catalysts prepared by urea-matrix combustion synthesis

η-Cycloheptatrienyl-molybdenum chemistry: Tertiary phosphine, alkyl, hydrido, halogeno and related derivatives

The heterogeneous reaction between propanal vapour and rare-earth-metal oxides gives as major products pentan-3-one and carbon dioxide. Residence time investigations indicate that pentan-3-one and carbon dioxide are primary products. Deactivation and high-resolution electron microscopy studies support the hypothesis that surface [O] participates in the reaction, and high oxygen mobilites in the oxide may allow defects to spread within the oxide. The carbon dioxide produced in the reaction poisons the lanthanum oxide leading to the faster deactivation and temperature-programmed desorption indicates the presence of a surface intermediate which decomposes to pentan-3-one and carbon dioxide. A mechanism is proposed in which the formation of pentan-3-one proceeds via surface-bound carboxylate species. Preliminary studies show that catalytic production of pentan-3-one can potentially be sustained by co-feeding water with propanal to the rare-earth-metal oxides.

Conversion of propanal to pentan-3-one using lanthanide oxides

The new compounds K[W(PMe3)3H5], [K(18-crown-6)][W(PMe3)3H5](18-crown-6 = 1,4,7,10,13,16-hexaoxacycloctadecane), Na[W(PMe3)3H5], [Na(15-crown-5)][W(PMe3)3H5], (15-crown-5 = 1,4,7,10,13-pentaoxacyclopentadecane), [{W(PMe3)3H5Li}4], K[W(η-C5H5)(PMe3)H4], [K(18-crown-6)][W(η-C5H5)(PMe3)H4], [K(18-crown-6)][W(η-C5H4Et)(PMe3)H4], K[cis-Re(PMe3)4H2], [K(18-crown-6)][cis-Re(PMe3)4H2], [W(PMe3)3H5(SnBun3)], [W(ηC5H5)(PMe3)H4(SnBun3)], [Re(PMe3)4H2(SnBun3)], [H(η-C5H5)2ZrW(PMe3)3H5], [Cl(η-C5H5)2ZrW(PMe3)3H5], [{(Ph3P)Au}3W(PMe3)3H4]Cl·xCH2Cl2 and [K(18-crown-6)][Mo(η-C5H5)2H] are reported The X-ray crystal structures of [K(18-crown-6)][W(PMe3)3H5], [Na(15-crown-5)][W(PMe3)3H5], [{W(PMe3)3H5Li}4], [K(18-crown-6)][cis-Re(PMe3)4H2], [{(Ph3P)Au}3W(PMe3)3H4]Cl·015CH2Cl2 and [K(18-crown-6)][Mo(η-C5H5)2H] have been determined The crystal structures of [K(18-crown-6)][W(PMe3)3H5] and [Na(15-crown-5)][W(PMe3)3H5] have also been determined by neutron diffraction Evidence for the presence of a degree of covalent bonding in the systems M–H–M′, where M = W and M′= Li, Na or K and M = Re, M′= K, is discussed

Transition metal–hydrogen–alkali metal bonds: synthesis and crystal structures of [K(18-crown-6)][W(PMe3)3H5], [Na(15-crown-5)][W(PMe3)3H5] and [{W(PMe3)3H5Li}4] and related studies

Malcolm L. H. Green

Papers

Applications of nanocomposites

Rationalizing the catalytic performance of γ-alumina-supported Co(Ni)–Mo(W) HDS catalysts prepared by urea-matrix combustion synthesis

η-Cycloheptatrienyl-molybdenum chemistry: Tertiary phosphine, alkyl, hydrido, halogeno and related derivatives

Conversion of propanal to pentan-3-one using lanthanide oxides

Transition metal–hydrogen–alkali metal bonds: synthesis and crystal structures of [K(18-crown-6)][W(PMe3)3H5], [Na(15-crown-5)][W(PMe3)3H5] and [{W(PMe3)3H5Li}4] and related studies