Nature Chemistry Contents May 2014 Volume 6 Number 5 pp 371-454

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Advertisement Everyday reliability for your lab's every UV-Vis need. Experience the confidence that only 50 years of innovation can bring to your daily use of spectrophotometers. Whether you are teaching colorimetric analysis or an industrial QA/QC manager monitoring product specifications, you can rely on the robust designs, ease-of-use and flexibility that Thermo Scientific ultraviolet-visible spectrophotometers provide. Find the right spectrophotometer to match your workflow. TABLE OF CONTENTS May 2014 Volume 6, Issue 5 Thesis Research Highlights Blogroll News and Views Articles Corrigendum Addenda In Your Element Subscribe   Facebook   RSS   Recommend to library   Twitter   Thesis Top The living lab   pp371 - 372 Bruce C. Gibb doi:10.1038/nchem.1931 Bruce Gibb finds wonder in the landscape of chemistry research. Research Highlights Top Reductive amination: H2 free reduction | Molecular recognition: Mutually exclusive | Aromatic substitution: A different direction | Drug discovery: Follow the pheromones' lead Blogroll Top Blogroll: Inviting ire and iron   p375 Tien Nguyen doi:10.1038/nchem.1929 News and Views Top Proton-coupled electron transfer: Free radicals under control   pp376 - 377 Bridgette A. Barry doi:10.1038/nchem.1936 Biological solar energy conversion requires the coordinated and rapid movement of protons and electrons through complex proteins, called reaction centres. Now, an artificial and structurally simple reaction centre has been synthesized that mimics an important, photosynthetic charge relay. See also: Article by Megiatto Jr et al. Protein folding: When ribosomes pick the structure   pp378 - 379 Elin M. Sivertsson and Laura S. Itzhaki doi:10.1038/nchem.1926 Anfinsen's principle tells us that the folded structure of a protein is determined solely by its sequence. Now, it has been shown that the rate at which a polypeptide chain is synthesized in the cell can affect which of two alternative folded structures it adopts. Synthetic Biology: Two-for-one designer labels   pp379 - 381 E. James Petersson and John B. Warner doi:10.1038/nchem.1935 Labelling of proteins with pairs of fluorophores enables their conformations to be studied; however, complete incorporation of labels in multiple, pre-defined locations is very difficult. Now, a combination of double unnatural amino acid mutagenesis and selective chemical modification offers a general method to achieve this. See also: Article by Wang et al. Polymer mechanochemistry: Flex, release and repeat   pp381 - 383 Nancy R. Sottos doi:10.1038/nchem.1927 Force-induced covalent bond changes in mechanophore-linked polymers typically require large, irreversible material deformation, limiting successive activation cycles. Now, repeated force-induced reactions have been achieved by incorporating flex-activated mechanophores into elastomeric networks. Cycloparaphenylenes: Closing the loop   pp383 - 385 Graham J. Bodwell doi:10.1038/nchem.1932 The synthesis of [5]CPP, the smallest and by far the most strained member of the family of macrocycles known as cycloparaphenylenes, has been reported in quick succession by two different research groups. But how long will the new record holder retain its title? See also: Article by Evans et al. Solar energy: Packing heat   pp385 - 386 Nathan R. Neale doi:10.1038/nchem.1933 Nanoscopic templates functionalized with light-reactive chromophores could ultimately be used to store solar energy and later release it as heat. Now, it has been shown that packing the chromophores together increases both storage capacity and lifetime. See also: Article by Kucharski et al. Chemistry JOBS of the week Lecturer in Chemistry Massey University New Zealand PhD Position in Physical Chemistry University of Geneva PhD fellowship The University of Hong Kong Postdoctoral Researcher Trinity College Dublin More Science jobs from Chemistry EVENT A Celebration of Organic Chemistry 2014 22.09.14 Surrey, UK More science events from Articles Top Unusual structure, bonding and properties in a californium borate   pp387 - 392 Matthew J. Polinski, Edward B. Garner, III, Rémi Maurice, Nora Planas, Jared T. Stritzinger et al. doi:10.1038/nchem.1896 Actinides generally form ionic compounds, however, when electron-rich ligands with large hyperpolarizabilities are used, partially covalent bonds can also form. Now a rare californium borate is shown to exhibit significant differences from other f-elements in its structure and bonding. Quantum mechanical calculations support Cf and ligand orbital interactions, also indicating partial covalent bonding. Optimized orthogonal translation of unnatural amino acids enables spontaneous protein double-labelling and FRET   pp393 - 403 Kaihang Wang, Amit Sachdeva, Daniel J. Cox, Nabil W. Wilf, Kathrin Lang et al. doi:10.1038/nchem.1919 A series of quadruplet decoding tRNAs has been developed to form an optimized orthogonal translation system. These tRNAs enable efficient, site-specific incorporation of multiple unnatural amino acids into a protein, with a substantial increase in yield over previous methods. The amino acids are then used to site-specifically label a protein with a pair of fluorophores, enabling studies of the protein's dynamics. See also: News and Views by Petersson & Warner Efficient room-temperature synthesis of a highly strained carbon nanohoop fragment of buckminsterfullerene   pp404 - 408 Paul J. Evans, Evan R. Darzi and Ramesh Jasti doi:10.1038/nchem.1888 Strained hydrocarbons are more than molecular curiosities — they often have promising materials properties, and even just making them offers challenges that push the limits of synthetic methods. Now, a short, efficient and room-temperature synthesis of [5]cycloparaphenylene, a carbon nanohoop with 119 kcal per mol of strain energy, is reported. Chemical compounds See also: News and Views by Bodwell Ultra stable self-assembled monolayers of N-heterocyclic carbenes on gold   pp409 - 414 Cathleen M. Crudden, J. Hugh Horton, Iraklii I. Ebralidze, Olena V. Zenkina, Alastair B. McLean et al. doi:10.1038/nchem.1891 Thiol-based self-assembled monolayers have a huge variety of potential applications but are hampered by oxidative and thermal instability. Now, N-heterocyclic carbenes are shown to form densely packed layers on Au(111) that are considerably more stable than thiol films, resisting hot organic solvents, acid, base, oxidant and oxidative electrohemical etching. Chemical compounds Self-powered enzyme micropumps   pp415 - 422 Samudra Sengupta, Debabrata Patra, Isamar Ortiz-Rivera, Arjun Agrawal, Sergey Shklyaev et al. doi:10.1038/nchem.1895 Self-powered micropumps that are turned on by the presence of their respective substrates are formed from surface-immobilized, ATP-independent enzymes. Coupling substrate-sensing with transport enables the design of devices that deliver cargo in response to specific stimuli. Demonstrated here is the release of insulin at a rate proportional to ambient glucose concentration. A bioinspired redox relay that mimics radical interactions of the Tyr–His pairs of photosystem II   pp423 - 428 Jackson D. Megiatto Jr, Dalvin D. Méndez-Hernández, Marely E. Tejeda-Ferrari, Anne-Lucie Teillout, Manuel J. Llansola-Portolés et al. doi:10.1038/nchem.1862 An artificial reaction centre has been designed that contains a benzimidazole–phenol model of the Tyr–His relay in photosystem II. It has been seen to mimic both the short internal hydrogen bond of the natural relay, and — using electron paramagnetic resonance —the relaxation behaviour that accompanies proton-coupled electron transfer in photosystem II. Chemical compounds See also: News and Views by Barry Switchable enantioseparation based on macromolecular memory of a helical polyacetylene in the solid state   pp429 - 434 Kouhei Shimomura, Tomoyuki Ikai, Shigeyoshi Kanoh, Eiji Yashima and Katsuhiro Maeda doi:10.1038/nchem.1916 Reversible chirality switching and memory is demonstrated in a helical polyacetylene. Both the helicity of the polymer backbone and the axial chirality of the side chains contribute to the memory effect. When used to produce a chiral stationary phase for a chromatographic enantiomer resolution it was possible to switch the elution order under identical chromatographic conditions. Chemical compounds Quantitative sequencing of 5-formylcytosine in DNA at single-base resolution   pp435 - 440 Michael J. Booth, Giovanni Marsico, Martin Bachman, Dario Beraldi and Shankar Balasubramanian doi:10.1038/nchem.1893 Cytosine base modifications 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC) and 5-formylcytosine (5fC) are present in mammalian DNA. Reduced bisulfite sequencing is now developed for quantitatively sequencing 5fC at single-base resolution. This method is then applied with oxidative bisulfite sequencing to gain a map of 5mC, 5hmC and 5fC in mouse embryonic stem cells. Templated assembly of photoswitches significantly increases the energy-storage capacity of solar thermal fuels   pp441 - 447 Timothy J. Kucharski, Nicola Ferralis, Alexie M. Kolpak, Jennie O. Zheng, Daniel G. Nocera et al. doi:10.1038/nchem.1918 Solar thermal fuels have recently attracted an increasing amount of attention as a potential method for solar energy capture, conversion, storage and utilization. Azobenzene-functionalized single-walled carbon nanotubes demonstrate the proof-of-principle for increasing kinetic stability and energy densities by templating photoswitchable molecules on nanostructures to achieve highly (con)strained configurations. Chemical compounds See also: News and Views by Neale Structural complexity through multicomponent cycloaddition cascades enabled by dual-purpose, reactivity regenerating 1,2,3-triene equivalents   pp448 - 452 Paul A. Wender, Dennis N. Fournogerakis, Matthew S. Jeffreys, Ryan V. Quiroz, Fuyuhiko Inagaki et al. doi:10.1038/nchem.1917 Cascade reactions allow step-economical generation of molecular complexity. Now, a butatriene equivalent, TMSCH2C ≡ CCH2OH, is used to couple two powerful and convergent cycloadditions — the homologous Diels–Alder ([5 + 2]) and the Diels–Alder ([4 + 2]) reactions –– through a vinylogous Peterson elimination, en route to a series of kinase inhibitors inspired by staurosporine. Chemical compounds Corrigendum Top Corrigendum: Large negative thermal expansion of a polymer driven by a submolecular conformational change   p453 Xingyuan Shen, Christopher Viney, Erin R. Johnson, Changchun Wang and Jennifer Q. Lu doi:10.1038/nchem.1922 Addenda Top Addendum: Diversity in the dynamical behaviour of a compartmentalized programmable biochemical oscillator   p453 Maximilian Weitz, Jongmin Kim, Korbinian Kapsner, Erik Winfree, Elisa Franco et al. doi:10.1038/nchem.1923 Addendum: Exceptionally fast carbon-carbon bond reductive elimination from gold(iii)   p453 W. J. Wolfe, M. S. Winston and F. D. Toste doi:10.1038/nchem.1930 In Your Element Top Poisonous polonium   p454 Eric Ansoborlo doi:10.1038/nchem.1928 Eric Ansoborlo considers the disproportionate potency of polonium compared with its relative scarcity on Earth. 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