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

Reduction using sodium amalgam of the complex [Mo(η-C6H6)(dmpe)(η-C3H5)]+(dmpe = Me2PCH2CH2PMe2) in the presence of the olefins L = ethylene, propene, or cyclopentene gives the neutral η2-olefin compounds [Mo(η-C6H6)(dmpe)L]. The η-ethylene compound readily protonates forming the hydrido-cation [Mo(η-C6H6)(dmpe)(η-C2H4)H]+. Treatment of this with the tertiary phosphines PR3, where R3= Me3 or Me2Ph, gives the η-ethylbenzene compounds [Mo(η)-C6H5Et)(dmpe)(PR3)H]PF6. The new compounds trans-[Mo(η-C6H6)(dmpe) H2], [{Mo(η-C6H6)(dmPe)}2(µ-dmpe)], [(Mo(η-C6H6)(dmpe)H}2(µ-dmpe)][PF6]2, [Mo(η-C6H6)-(η-C3H5)(PMe3)Cl], [Mo(η-C6H6)(PMe3)3], and [Mo(η-C6H6)(PMe3)3H]PF6 are also described.

Arene-molybdenum chemistry: olefin and hydride derivatives

The compounds [{(η-C5H5)MoH[µ-(η1):η5-C5H4]}2](two isomers), [{(η-C5H5)MoH}2{µ-(η5-C5H4-η5-C5H4)}], [{(η-C5H5)MoH}2(µ-H){µ-(η5-C5H4-η5-C5H4)]PF6, [{(η-C5H5)MoI}2[µ-(η5-C5H4-η5-C5H4)]}] and [{(η-C5H5)Mo}2(µ-OH)(µ-H){µ-(η5-C5H4-η5-C5H4)}]2PF6 are described, and the X-ray crystal structure of the last of these is reported.

Synthesis and reactions of molybdenocene dimers: X-ray crystal structure of the salt [{(η-C5H5)Mo}2(µ-OH)(µ-H){µ-(η5-C5H4-η5-C5H4)}]2PF6·½H2O

Synthesis of hetero-binuclear derivatives of the tetrathiolato complexes [Mo(η-C5H5CH2SR)2)], R = Prn and Ph, with platinum, palladium, and rhodium

The reduction of nitric oxide by arc vaporized carbons (AVC) including the compound C 60 , fullerene soot and carbon nanotubes, giving dinitrogen and carbon oxides has been studied. It is found that the AVC carbons are more active towards oxidation by NO than by oxygen gas at low temperatures (300–400°C). In contrast, conventional carbons such as graphite and microporous carbons are more readily oxidised by oxygen than by NO. The addition of copper salts and to a lesser extent, cobalt salts, to fullerene soot substantially promote NO reduction. The high intrinsic activity for NO reduction by AVC carbons compared to graphitic carbons is attributed to the presence of five membered carbon rings in the AVC carbons.

Reduction of nitric oxide by arc vaporized carbons (AVC)

We studied the effect of body position in humans on the relationship between exhaled vital capacity (VC) and both helium (He) and nitrogen (N2) concentrations after delivery of an He bolus at residual volume (RV) followed by 100% oxygen to total lung capacity. Phase IV, defined as the % VC at the first sharp and permanent increase in N2 and He, occurred at a mean of 15.7% VC while seated, 60.0% VC in right lateral and 59.6% VC in left lateral positions. He bolus delivery above RV but well below 60% VC resulted in the disappearance of phase IV. Lung pressure-volume (PV) curves had inflections at the volume of phase IV in the seated position: but the inflections were well below phase IV in lateral positions. Phase IV increased to higher volumes at higher mouth pressures. The relationship between phase IV and mouth pressure fell near the respiratory system relaxation PV curves. The findings suggest the higher phase IV in lateral positions is due to sequence of emptying without airway closure and is influenced by active expiration.

Malcolm L. H. Green

Papers

Arene-molybdenum chemistry: olefin and hydride derivatives

Synthesis and reactions of molybdenocene dimers: X-ray crystal structure of the salt [{(η-C5H5)Mo}2(µ-OH)(µ-H){µ-(η5-C5H4-η5-C5H4)}]2PF6·½H2O

Synthesis of hetero-binuclear derivatives of the tetrathiolato complexes [Mo(η-C5H5CH2SR)2)], R = Prn and Ph, with platinum, palladium, and rhodium

Reduction of nitric oxide by arc vaporized carbons (AVC)

Relationship of phase IV to closing volume in lateral body positions.