Nature Chemistry Contents May 2015 Volume 7 Number 5 pp361 - 464

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TABLE OF CONTENTS May 2015 Volume 7, Issue 5 Feature Thesis Books and Arts Research Highlights Blogroll News and Views Correction Perspective Articles Addenda In Your Element Subscribe   Facebook   RSS   Recommend to library   Twitter   Advertisement Nature Outlook Biomaterials The Nature Outlook: Biomaterials examines the many ways in which solutions created by the natural world - by spiders, mussels, geckos, lotus leaves and more - are inspiring technological imitations that surpass some of the best existing human-engineered substances.   Access the Outlook free online for six months. Produced with support from: KISCO Ltd. in association with Spiber Inc.    Feature Top Quantum reform   pp361 - 363 Leonie Mueck doi:10.1038/nchem.2248 Quantum computers potentially offer a faster way to calculate chemical properties, but the exact implications of this speed-up have only become clear over the last year. The first quantum computers are likely to enable calculations that cannot be performed classically, which might reform quantum chemistry — but we should not expect a revolution. Thesis Top The organic Solar System   pp364 - 365 Bruce C. Gibb doi:10.1038/nchem.2241 In the second of two essays looking at organic chemistry that can be found in the Solar System, Bruce C. Gibb focuses on the gas and ice giants as well as their satellites — concluding the tour on Saturn's fascinating moon Titan. Books and Arts Top Lecture: All about the arrow   pp366 - 367 Peter Scott doi:10.1038/nchem.2235 The science of silliness   p367 Stuart Cantrill reviews What If? Serious Scientific Answers to Absurd Hypothetical Questions by Randall Munroe doi:10.1038/nchem.2243 Research Highlights Top Organic synthesis: Made by machine | Deuterated drugs: Relief from racemization | Molecular logic: Detection on the edge | Theoretical chemistry: Electrides explained Blogroll Top Blogroll: Comment etiquette   p369 François-Xavier Coudert doi:10.1038/nchem.2239 News and Views Top Surface chemistry: Self-assembling Sierpiński triangles   pp370 - 371 Steven L. Tait doi:10.1038/nchem.2238 Defect-free Sierpiński triangles can be self-assembled on a silver surface through a combination of molecular design and thermal annealing. Three-fold halogen-bonding arrays and precise surface epitaxy preclude structural errors, thus enabling the high-level complexity of these supramolecular fractal patterns. See also: Article by Shang et al. Chemical biology: Chromatin chemistry goes cellular   pp371 - 373 Wolfgang Fischle, Dirk Schwarzer and Henning D. Mootz doi:10.1038/nchem.2249 Analysing post-translational modifications of histone proteins as they occur within chromatin is challenging due to their large number and chemical diversity. A major step forward has now been achieved by using split intein chemistry to engineer functionalized histones within cells. See also: Article by David et al. Aromaticity: A light-switched yin and yang pair   pp373 - 375 Henrik Ottosson and K. Eszter Borbas doi:10.1038/nchem.2242 In 1972, Baird showed theoretically that the electron counting rule for aromaticity and antiaromaticity in the lowest ππ* triplet state is opposite to that in the electronic ground state. A pair of compounds that manifests this reversal in character has now been identified and characterized experimentally for the first time. See also: Article by Sung et al. Natural products: Hunting microbial metabolites   pp375 - 376 Eric W. Schmidt doi:10.1038/nchem.2252 Symbiotic bacteria synthesize many specialized small molecules; however, establishing the role these chemicals play in human health and disease has been difficult. Now, the chemical structure and mechanism of the Escherichia coli product colibactin provides insight into the link between this secondary metabolite and colorectal cancer. See also: Article by Vizcaino & Crawford Hydrogen purification: MOF membranes put to the test   pp377 - 378 Tina M. Nenoff doi:10.1038/nchem.2218 Membranes are key components for the removal of greenhouse gases during fuel generation processes, such as hydrogen production, but simultaneous permeability and selectivity is difficult to obtain. This has now been achieved in ultrathin membranes that use the size-selective porosity of metal-organic frameworks to separate CO2 from H2. Heterogeneous catalysis: Scaling the rough heights   pp378 - 380 J. Will Medlin and Matthew M. Montemore doi:10.1038/nchem.2245 Scaling relations between the molecular structures of reactive intermediates and the strength of the bonds they form with flat surfaces have now been extended to also predict how bonding strength is affected by surface topography. These relations can be applied to design more efficient nanoparticle catalysts. See also: Article by Calle-Vallejo et al. Chemistry JOBS of the week Professor of Chemistry (Open Rank) Universität Basel In-Residence Track Faculty Position in Medicinal Chemistry UCSF - Institute for Neurodegenerative Diseases Senior Lecturers - Readers in the Department of Chemistry King's College London Graduate Student Positions available in Bioanalytical Chemistry University of Texas at El Paso Postdoctoral fellow Virginia Commonwealth University More Science jobs from Chemistry EVENT Third EuCheMS Inorganic Chemistry Conference "Chemistry over the horizon" 28th June - 1st July 2015 Wroclaw, Poland More science events from Correction Top Correction   p380 doi:10.1038/nchem.2231 Perspective Top Exploiting chemically selective weakness in solids as a route to new porous materials   pp381 - 388 Russell E. Morris and Jiří Čejka doi:10.1038/nchem.2222 New synthetic routes to porous materials can be developed by taking advantage of a solid's weaknesses. This approach can lead to new products that break the rules of what is currently feasible. Articles Top Assembling molecular Sierpiński triangle fractals   pp389 - 393 Jian Shang, Yongfeng Wang, Min Chen, Jingxin Dai, Xiong Zhou et al. doi:10.1038/nchem.2211 A series of molecular fractals, specifically Sierpiński triangles, can be assembled on a Ag(111) surface from small, bent oligophenyls with a bromo group at each end. The self-assembly is driven by the formation of synergistic halogen and hydrogen bonds between the molecular building blocks, and defect-free structures with more than 100 individual components are observed. Chemical compounds See also: News and Views by Tait Chemical tagging and customizing of cellular chromatin states using ultrafast trans-splicing inteins   pp394 - 402 Yael David, Miquel Vila-Perelló, Shivam Verma and Tom W. Muir doi:10.1038/nchem.2224 A method for engineering site-specific modifications of histone proteins within cellular chromatin has been developed using protein trans-splicing. This approach enabled a native histone modification, H2BK120 ubiquitination, to be incorporated in isolated nuclei, which was shown to trigger a downstream epigenetic effect. See also: News and Views by Fischle et al. Introducing structural sensitivity into adsorption–energy scaling relations by means of coordination numbers   pp403 - 410 Federico Calle-Vallejo, David Loffreda, Marc T. M. Koper and Philippe Sautet doi:10.1038/nchem.2226 Scaling relations between the adsorption energies of reaction intermediates facilitate the computational design of catalysts. However, these relations are restricted to low-index surfaces and how they differ from surface to surface cannot be predicted. Structural sensitivity has now been incorporated into scaling relations by elucidating how they are affected by the coordination number of an adsorption site. See also: News and Views by Medlin & Montemore The colibactin warhead crosslinks DNA   pp411 - 417 Maria I. Vizcaino and Jason M. Crawford doi:10.1038/nchem.2221 Genotoxic small molecules from the bacterial colibactin pathway — a gut-associated non-ribosomal peptide synthetase–polyketide synthase hybrid gene cluster linked to colorectal cancer — have remained elusive due to their instability. Now, one of these, the colibactin warhead, an unprecedented substituted spirobicyclic structure, has been characterized and shown to crosslink duplex DNA in vitro. See also: News and Views by Schmidt Reversal of Hückel (anti)aromaticity in the lowest triplet states of hexaphyrins and spectroscopic evidence for Baird's rule   pp418 - 422 Young Mo Sung, Min-Chul Yoon, Jong Min Lim, Harapriya Rath, Koji Naoda et al. doi:10.1038/nchem.2233 In the ground state, aromatic rings contain [4n + 2] π electrons whereas antiaromatic systems have [4n] π-electrons. Baird's rule states that this situation is reversed in the lowest triplet excited state. It has now been shown using a combination of spectroscopy and quantum chemical calculations that two closely related bis-rhodium hexaphyrins exhibit properties consistent with Baird's rule. See also: News and Views by Ottosson & Borbas A protonation-coupled feedback mechanism controls the signalling process in bathy phytochromes   pp423 - 430 Francisco Velazquez Escobar, Patrick Piwowarski, Johannes Salewski, Norbert Michael, Maria Fernandez Lopez et al. doi:10.1038/nchem.2225 Photoswitching of phytochromes is based on the isomerization of the tetrapyrrole chromophore, and eventually leads to the (de)activation of an enzymatic output module. Now it has been shown that both the structural changes associated with photoswitching and the thermal decay of the light-activated state are coupled to proton translocations in the chromophore pocket. Structure and biosynthesis of a macrocyclic peptide containing an unprecedented lysine-to-tryptophan crosslink   pp431 - 437 Kelsey R. Schramma, Leah B. Bushin and Mohammad R. Seyedsayamdost doi:10.1038/nchem.2237 Structural elucidation of a peptide natural product has revealed an unprecedented post-translational modification involving formation of a carbon–carbon bond between the side-chains of lysine and tryptophan. This motif defines a new family of cyclic peptides. Biochemical studies reveal that this C-C bond is generated by a radical SAM enzyme, and delineate its catalytic mechanism. Chemical compounds Functionalization of cobalt porphyrin–phospholipid bilayers with his-tagged ligands and antigens   pp438 - 446 Shuai Shao, Jumin Geng, Hyun Ah Yi, Shobhit Gogia, Sriram Neelamegham et al. doi:10.1038/nchem.2236 Lipid bilayers containing porphyin-phospholipid that is chelated with cobalt have been shown to capture his-tagged proteins and peptides. This method offers a simple route for functionalizing pre-formed lipid bilayers without disrupting their integrity. Using this approach homing peptides were attached to cargo-loaded liposomes to enable tumour targeting, and an HIV-derived protein fragment elicited antibodies following binding to immunogenic liposomes. An aptamer-functionalized chemomechanically modulated biomolecule catch-and-release system   pp447 - 454 Ankita Shastri, Lynn M. McGregor, Ya Liu, Valerie Harris, Hanqing Nan et al. doi:10.1038/nchem.2203 The extraction of (bio)molecules from fluid mixtures is vital for applications ranging from biomedical diagnostics to environmental analysis. Now a robust chemomechanical sorting system for the extraction of thrombin is described in which pH-dependent binding of the analyte to a specific aptamer is combined with volume changes of the pH-responsive hydrogel in a biphasic microfluidic regime, resulting in a catch-and-release system. A protein-targeting strategy used to develop a selective inhibitor of the E17K point mutation in the PH domain of Akt1   pp455 - 462 Kaycie M. Deyle, Blake Farrow, Ying Qiao Hee, Jeremy Work, Michelle Wong et al. doi:10.1038/nchem.2223 It is difficult to develop a selective ligand for point mutations in proteins that are not found in easily addressable locations. Now, an all-chemical, epitope-targeting strategy has been reported, and was used to discover an inhibitory peptide with selectivity for the E17K point mutation in the PH Domain of the Akt1 oncoprotein. Chemical compounds Addenda Top Addendum: Mechanochemistry: Tearing apart triazoles   p463 Stuart Cantrill doi:10.1038/nchem.2247 Addendum: Mechanochemistry: Forcing a molecule's hand   p463 S. Karthikeyan and Rint P. Sijbesma doi:10.1038/nchem.2246 In Your Element Top Potent potassium   p464 Lars Öhrström doi:10.1038/nchem.2244 Lars Öhrström ponders the importance of potassium in matters of life and death. 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