Nature Chemistry Contents July 2012 Volume 4 Number 7 pp 513-586

Advertisement Looking to keep pace with global news and research in the chemical sciences? Join RSC e-membership today to receive a digital subscription to Chemistry World, the unrivalled monthly magazine with an international readership of 49,000 scientists. Access the latest developments in research and government policy, business news, features and opinion columns, jobs board, and networking opportunities. TABLE OF CONTENTS July 2012 Volume 4, Issue 7 Thesis Research Highlights Blogroll Correction News and Views Articles In Your Element Subscribe   Facebook   RSS   Recommend to library   Twitter   Advertisement The Naturejobs Career Expo London 2012 UK's largest career fair and conference focused exclusively on the scientific world. 20 September 2012 - Business Design Centre, London, UK Register today! Career fair is FREE of charge. Conference fee is £40.   Thesis Top Lies, damned lies and h-indices   pp513 - 514 Bruce C. Gibb doi:10.1038/nchem.1388 Sometimes the numbers just don't add up — and Bruce Gibb explains why. Research Highlights Top Metal-organic frameworks: The big indoors | Photochemical switches: Control of a cofactor | Electrocatalysis: Lead lends a hand | Anion topology: Surprising sulfate species Blogroll Top Blogroll: #WhatsInLemiShine   p517 doi:10.1038/nchem.1390 Correction Top Correction   p517 doi:10.1038/nchem.1382 News and Views Top Protein recognition: Calixarene connection   pp519 - 520 Thomas Schrader doi:10.1038/nchem.1386 Supramolecular ligands are promising tools for interacting with proteins, but how exactly they bind together has so far been difficult to characterize. An unambiguous picture of the interaction between a synthetic ligand and the surface of cyctochrome c has now been obtained in solution and in the solid state. See also: Article by McGovern et al. Natural product biosynthesis: Tackling tunicamycin   pp520 - 521 Ethan D. Goddard-Borger and Stephen G. Withers doi:10.1038/nchem.1391 The tunicamycins, secondary metabolites of various Streptomyces species, are invaluable tools in glycobiology. It has now been shown that their biosynthesis involves an unusual exo-glycal intermediate produced by previously unknown short-chain dehydrogenase/reductase activity. See also: Article by Wyszynski et al. Reaction mechanisms: Stripping down SN2   pp522 - 523 Andrew J. Orr-Ewing doi:10.1038/nchem.1377 The mechanism of the SN2 reaction is fundamental to understanding and controlling the stereochemistry of organic reactions, but surrounding solvent molecules may complicate the textbook picture. Micro-solvation studies have now explored the stereochemical consequences of the presence of one or two solvent molecules. See also: Article by Otto et al. Photochemistry: Molecular motor speed limits   pp523 - 525 R. J. Dwayne Miller doi:10.1038/nchem.1393 To improve the efficiency of molecular motors, a better understanding of the dynamics of their functional motions is required. Now, ultrafast fluorescence spectroscopy has been used to monitor the excited-state evolution of a light-driven molecular motor. See also: Article by Conyard et al. Main group chemistry: Breaking the limits with silylenes   pp525 - 526 Matthias Driess doi:10.1038/nchem.1387 The successful synthesis of acyclic silylenes that are isolable at ambient temperature offers striking new opportunities to use stable silylenes for the activation of important small molecules such as dihydrogen and alkanes — hitherto almost completely the domain of transition metals. ** THIS IS THE NATURE JOBS/EVENTS BOX - content for this box will be produced via an offline PERL script ** Articles Top Protein camouflage in cytochrome c–calixarene complexes   pp527 - 533 Róise E. McGovern, Humberto Fernandes, Amir R. Khan, Nicholas P. Power and Peter B. Crowley doi:10.1038/nchem.1342 A calixarene–protein host–guest complex has been characterized in detail by using a combination of NMR spectroscopy and X-ray crystallography. The water-soluble sulfonato-calix[4]arene binds to cytochrome c at various lysine residues to yield a dynamic complex. This interaction may serve to facilitate crystallization by mediating protein–protein contacts. See also: News and Views by Schrader Single solvent molecules can affect the dynamics of substitution reactions   pp534 - 538 R. Otto, J. Brox, S. Trippel, M. Stei, T. Best and R. Wester doi:10.1038/nchem.1362 How do solvent molecules influence the dynamics of a chemical reaction? Crossed-beam molecular imaging experiments reveal how different reaction mechanisms can be either suppressed or enhanced by the presence of one water molecule. The study finds that steric effects are responsible for the observed dynamics. See also: News and Views by Orr-Ewing Biosynthesis of the tunicamycin antibiotics proceeds via unique exo-glycal intermediates   pp539 - 546 Filip J. Wyszynski, Seung Seo Lee, Tomoaki Yabe, Hua Wang, Juan Pablo Gomez-Escribano, Mervyn J. Bibb, Soo Jae Lee, Gideon J. Davies and Benjamin G. Davis doi:10.1038/nchem.1351 Construction of the remarkable 11-carbon frame of the antibiotic tunicamycin is shown to use cyclic enol ethers (exo-glycals) — the first time such intermediates have been seen in biology. Exo-glycal synthase TunA uses an elegantly subtle mechanism to control regioselectivity and with exo-glycal epimerase TunF sets a logical chemical stage for downstream radical C–C coupling. See also: News and Views by Goddard-Borger & Withers Ultrafast dynamics in the power stroke of a molecular rotary motor   pp547 - 551 Jamie Conyard, Kiri Addison, Ismael A. Heisler, Arjen Cnossen, Wesley R. Browne, Ben L. Feringa and Stephen R. Meech doi:10.1038/nchem.1343 The light-driven power stroke of a unidirectional molecular motor is studied using ultrafast fluorescence spectroscopy. The evolution on the excited-state energy surface is observed on the 100 fs timescale and is accompanied by damped coherent molecular motion. The implications of these observations for the operation of the molecular motors are discussed. See also: News and Views by Miller Closed-shell and open-shell square-planar iridium nitrido complexes   pp552 - 558 Markus G. Scheibel, Bjorn Askevold, Frank W. Heinemann, Edward J. Reijerse, Bas de Bruin and Sven Schneider doi:10.1038/nchem.1368 Coupling reactions of nitrogen atoms represent elementary steps to many important, heterogeneously catalysed reactions, such as the Haber–Bosch process or selective catalytic reduction of NOx to N2. Here, the synthesis and characterization of closed- and open-shell, square-planar iridium nitrido complexes is described, indicating considerable nitridyl radical character for the open shell complex. Mechanically induced chemiluminescence from polymers incorporating a 1,2-dioxetane unit in the main chain   pp559 - 562 Yulan Chen, A. J. H. Spiering, S. Karthikeyan, Gerrit W. M. Peters, E. W. Meijer and Rint P. Sijbesma doi:10.1038/nchem.1358 Bisadamantyl 1,2-dioxetane is a luminescent mechanophore that, when incorporated into polymer chains or networks, emits visible light when its 4-membered ring is opened by sonication in solution or by deformation of a bulk sample. This phenomenon mimics biological mechanoluminescence and highlights the potential to study the failure of polymeric materials with high spatial and temporal resolution. Controlled homocatenation of boron on a transition metal   pp563 - 567 Holger Braunschweig, Qing Ye, Alfredo Vargas, Rian D. Dewhurst, Krzysztof Radacki and Alexander Damme doi:10.1038/nchem.1379 Mild, controllable homocatenation of many elements is a considerable challenge, usually due to their low homonuclear σ-bond enthalpy. This is particularly difficult for boron, despite its high homonuclear σ-bond enthalpy. The controllable metal-templated catenation of four boron atoms is now demonstrated — a step towards oligomers of monovalent boron and polyboranes. Non-Markovian polymer reaction kinetics   pp568 - 573 T. Guérin, O. Bénichou and R. Voituriez doi:10.1038/nchem.1378 Quantifying polymer reaction kinetics requires the non-Markovian dynamics of monomer motion to be taken into account. This difficulty is overcome by explicitly determining the typical reactive conformations of the polymer, which are found to be more extended than equilibrium conformations, leading to reaction times significantly shorter than predicted by existing Markovian theories. The synthesis, crystal structure and charge-transport properties of hexacene    pp574 - 578 Motonori Watanabe, Yuan Jay Chang, Shun-Wei Liu, Ting-Han Chao, Kenta Goto, Md. Minarul Islam, Chih-Hsien Yuan, Yu-Tai Tao, Teruo Shinmyozu and Tahsin J. Chow doi:10.1038/nchem.1381 Crystals of hexacene prepared from a monoketone precursor are found to be stable up to 300 °C in the dark, but readily decompose when exposed to light. An organic-field transistor made with a single crystal of hexacene was found to have superior properties to one made from pentacene under analogous conditions. An improved high-performance lithium–air battery   pp579 - 585 Hun-Gi Jung, Jusef Hassoun, Jin-Bum Park, Yang-Kook Sun and Bruno Scrosati doi:10.1038/nchem.1376 Lithium–air batteries have the possibility of having a very high energy density, but their use has been hampered by a limited number of charge–discharge cycles and a low current-rate capability. Now, exploiting a suitable, stable electrolyte allows an advanced lithium–air battery to operate with many cycles at various capacity and rate values. In Your Element Top Peculiar protactinium   p586 Richard Wilson doi:10.1038/nchem.1389 Richard Wilson relates how the rare, highly radioactive, highly toxic element protactinium puzzled chemists for a long time, and was discovered and named twice from two different isotopes before finding its place in fundamental research. Top Advertisement Scientific Reports publishes 457 open access papers in its first year Publishing technically sound research articles, Scientific Reports is Nature Publishing Group’s fastest growing journal. Given the speed and visibility offered, no wonder 93% of our authors said that they are “likely” or “very likely” to submit again. Keep your research moving. Submit to Scientific Reports   Natureevents is a fully searchable, multi-disciplinary database designed to maximise exposure for events organisers. The contents of the Natureevents Directory are now live. The digital version is available here. 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