Angewandte Chemie International Edition
Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
The following papers are very important in the opinion of two referees.
You are invited to comment on published VIPs. Please use the link given at the end of each such abstract. Scientific comments may be forwarded to the authors by the editorial office and may be posted on this page. Kindly let us know if your comments are for the editorial office only, the author, or the public as well.
Dynamic Mirror-Symmetry Breaking in Bicontinuous Cubic Phases
Christian Dressel, Prof. Dr. Feng Liu, Dr. Marko Prehm, Dr. Xiangbing Zeng, Prof. Dr. Goran Ungar and Prof. Dr. Carsten Tschierske
Cubics with a twist: Polycatenar 5,5′-diphenyl-2,2′-bithiophenes (see picture) form two types of bicontinuous cubic phases. Though the molecules are achiral the cubic phase is always chiral, while the phase is achiral. The explanation is that in the phase the opposing chiralities of the two enantiomorphic networks cancel, but not so in the three-networks phase.
A Hexameric Peptide Barrel as Building Block of Amyloid-β Protofibrils
Dr. Christofer Lendel, Dr. Morten Bjerring, Dr. Anatoly Dubnovitsky, Robert T. Kelly, Dr. Andrei Filippov, Prof. Dr. Oleg N. Antzutkin, Prof. Dr. Niels Chr. Nielsen and Prof. Dr. Torleif Härd
Amyloid-β protofibrils are precursors to amyloid fibrils found in plaques in the brains of patients with Alzheimer’s disease. A stable form of Aβ protofibrils was engineered and studied by solid-state NMR spectroscopy. The structural model of hexameric building block oligomers clarifies biochemical issues related to the formation of protofibrils.
The Formation of Imidazolium Salt Intimate (Contact) Ion Pairs in Solution
Marcileia Zanatta, Dr. Anne-Lise Girard, Nathalia M. Simon, Prof. Gunter Ebeling, Prof. Hubert K. Stassen, Prof. Paolo R. Livotto, Prof. Francisco P. dos Santos and Prof. Jairton Dupont
Remote pKa control is the result of the formation of intimate contact ion pairs in CDCl3 and CD3CN of 1-n-butyl-2,3-dimethyl imidazolium ionic liquids associated with HCO3 or prolinate anions. These salts are effective neutral catalysts for the H/D exchange reaction from CDCl3 to substrates containing acidic H.
Bowl-like SnO2@Carbon Hollow Particles as an Advanced Anode Material for Lithium-Ion Batteries
Jin Liang, Dr. Xin-Yao Yu, Han Zhou, Hao Bin Wu, Prof. Shujiang Ding and Xiong Wen (David) Lou
Super Bowl: A bowl-like hybrid hollow nanostructure of SnO2@carbon is designed and fabricated as an anode material for lithium-ion batteries. With advantages of the unique architecture, the bowl-like SnO2@carbon particles are able to deliver a high discharge capacity of 963 mAh g−1 even after 100 cycles at a current density of 0.4 A g−1.
Semisynthesis of Biologically Active Glycoforms of the Human Cytokine Interleukin 6
Andreas Reif, Sebastian Siebenhaar, Andrea Tröster, Marina Schmälzlein, Carolin Lechner, Phanindra Velisetty, Karen Gottwald, Claudia Pöhner, Irene Boos, Volker Schubert, Prof. Stefan Rose-John and Prof. Carlo Unverzagt
The sequence matters: The human cytokine interleukin 6 (IL-6) was synthesized in two glycoforms by sequential native chemical ligation from two recombinant fragments (A, C) and a synthetic glycopeptide (B). Only one of the possible sequences of ligations efficiently led to the IL variants because of the susceptibility of the peptide chain and the folded glycoprotein to nonphysiological conditions.
Ultrahigh Energy Density Realized by a Single-Layer β-Co(OH)2 All-Solid-State Asymmetric Supercapacitor
Shan Gao, Dr. Yongfu Sun, Fengcai Lei, Liang Liang, Jiawei Liu, Wentuan Bi, Prof. Bicai Pan and Prof. Yi Xie
An atomically thin β-Co(OH)2 sheet electrode was used to fabricate an all-solid-state asymmetric supercapacitor with high energy density. The β-Co(OH)2 layers are characterized by 100 % exposed hydrogen atoms, thus facilitating efficient Faradaic redox reactions. The energy density of 98.9 Wh kg−1 can compete with the world’s highest energy density for supercapacitors.
Photo-Organocatalysis of Atom-Transfer Radical Additions to Alkenes
Dr. Elena Arceo, Dr. Elisa Montroni and Prof. Dr. Paolo Melchiorre
Light and simple: An organic molecule as simple as p-anisaldehyde can efficiently catalyze the intermolecular atom-transfer radical addition of a variety of haloalkanes onto olefins. The protocol requires irradiation from a household 23 W compact fluorescent light (CFL) bulb to proceed, and ambient temperature is sufficient to functionalize olefins in a synthetically useful fashion.
De Novo 3D Structure Determination from Sub-milligram Protein Samples by Solid-State 100 kHz MAS NMR Spectroscopy
Dr. Vipin Agarwal, Susanne Penzel, Kathrin Szekely, Riccardo Cadalbert, Emilie Testori, Andres Oss, Jaan Past, Prof. Ago Samoson, Prof. Matthias Ernst, Dr. Anja Böckmann and Prof. Beat H. Meier
Smaller and faster: The 3D structure of a model protein was determined with a protein sample one-fortieth of the usual amount thanks to 100 kHz magic-angle-spinning NMR spectroscopy.
Tramadol—A True Natural Product?
Dr. Souvik Kusari, Dr. Simplice Joel N. Tatsimo, Dr. Sebastian Zühlke, Dr. Ferdinand M. Talontsi, Prof. Dr. Simeon Fogue Kouam and Prof. Dr. Michael Spiteller
The root of the problem: Tramadol, a synthetic analgesic, was recently detected in the roots of the Cameroonian medicinal plant Nauclea latifolia. However, tramadol is not a natural product. Along with its major mammalian metabolites, tramadol is present in the roots of N. latifolia and other plant species, as well as in soil and local water sources in the Far North region of Cameroon as a result of anthropogenic contamination.
Translating Bacterial Detection by DNAzymes into a Litmus Test
Kha Tram, Pushpinder Kanda, Prof. Dr. Bruno J. Salena, Prof. Dr. Shuangyan Huan and Prof. Dr. Yingfu Li
A new way to use the litmus test: Cheap and widely available litmus dyes and pH papers have been used to achieve the detection of a bacterial pathogen (star) through the use of an RNA-cleaving DNAzyme (RCD), urease (Ur), and magnetic beads (MB). The method allowed the sensitive detection of E. coli in complex sample matrices such as apple juice, milk, and lake water.
Chemical Probes for the Functionalization of Polyketide Intermediates
Dr. Elena Riva, Dr. Ina Wilkening, Silvia Gazzola, W. M. Ariel Li, Dr. Luke Smith, Prof. Peter F. Leadlay and Dr. Manuela Tosin
Towards novel “unnatural” products: Fermentation of ACP mutants of S. lasaliensis in the presence of functionalized chemical probes with subsequent site-selective modifications generates a library of nonnatural lasalocid A precursors and derivatives.
Nanocrystalline-Graphene-Tailored Hexagonal Boron Nitride Thin Films
Kang Hyuck Lee, Dr. Hyeon-Jin Shin, Dr. Brijesh Kumar, Han Sol Kim, Jinyeong Lee, Dr. Ravi Bhatia, Dr. Sang-Hyeob Kim, In-Yeal Lee, Dr. Hyo Sug Lee, Prof. Gil-Ho Kim, Prof. Ji-Beom Yoo, Dr. Jae-Young Choi and Prof. Sang-Woo Kim
A hexagonal boron nitride (h-BN) thin film with an atomically flat surface was obtained using unintentionally formed nanocrystalline graphene (nc-G). A wafer-scale dielectric h-BN thin film was synthesized on a bare sapphire substrate by assistance of nc-G, which prevented structural deformations during chemical vapor deposition. The sp3-hybridized edges of nc-G play a key role during these processes.
Separating Para and Ortho Water
Dr. Daniel A. Horke, Dr. Yuan-Pin Chang, Karol Długołęcki and Prof. Dr. Jochen Küpper
Keep them separated: The two nuclear-spin isomers para and ortho water can be isolated in their absolute ground state in pure molecular beams. No pure para sample had previously been produced. This method for the separation of quantum states is generally applicable to all polar neutral molecules and allows the spatial separation of single quantum states and nuclear-spin isomers.
Watson–Crick Base Pairing Controls Excited-State Decay in Natural DNA
Dominik B. Bucher, Alexander Schlueter, Prof. Dr. Thomas Carell and Prof. Dr. Wolfgang Zinth
Shedding light on DNA: The excited-state dynamics of each nucleobase in calf thymus DNA following UV excitation could be determined with femtosecond IR spectroscopy. It was shown that the Watson–Crick base pairing opens up a new excited-state decay channel in double-stranded DNA, an effect that deactivates charge-transfer states.
Dissecting Ubiquitin Signaling with Linkage-defined and Protease Resistant Ubiquitin Chains
Tatjana Schneider, Dr. Daniel Schneider, Daniel Rösner, Saurav Malhotra, Franziska Mortensen, Prof. Dr. Thomas U. Mayer, Prof. Dr. Martin Scheffner and Prof. Dr. Andreas Marx
It all clicks into place: The fate of ubiquitylated proteins is determined by the topology of the attached ubiquitin chains. A new concept is reported for generating linkage-defined ubiquitin chains that are resistant to de-ubiquitylating enzymes and adopt native-like functions. The potential of these artificial chains for analyzing ubiquitin signaling is demonstrated by topology-specific effects on cell-cycle progression.
Epitaxial Seeded Growth of Rare-Earth Nanocrystals with Efficient 800 nm Near-Infrared to 1525 nm Short-Wavelength Infrared Downconversion Photoluminescence for In Vivo Bioimaging
Rui Wang, Xiaomin Li, Lei Zhou and Prof. Dr. Fan Zhang
A multi-shell nanocrystal was synthesized and used as an effective probe for in vivo imaging. With emission in the short-wavelength infrared region at 1525 nm, the probe is detectable in tissues at depths of up to 18 mm with a low detection threshold.
Unravelling the Correlation between the Aspect Ratio of Nanotubular Structures and Their Electrochemical Performance To Achieve High-Rate and Long-Life Lithium-Ion Batteries
Dr. Yuxin Tang, Dr. Yanyan Zhang, Jiyang Deng, Dr. Dianpeng Qi, Wan Ru Leow, Jiaqi Wei, Dr. Shengyan Yin, Prof. Zhili Dong, Prof. Rachid Yazami, Prof. Zhong Chen and Prof. Xiaodong Chen
A new aspect: When titanate-based nanotubes are used to fabricate electrode materials, the aspect ratio of the nanostructures correlates with the electrochemical performance in lithium-ion batteries. These insights should be useful in the development of efficient energy devices based on nanomaterials.
Bipolar Tribocharging Signal During Friction Force Fluctuations at Metal–Insulator Interfaces
Dr. Thiago A. L. Burgo and Dr. Ali Erdemir
Friction force fluctuation and tribocurrent generation at metal–insulator interfaces show a strong correlation during sliding contacts. The reported results suggest that these two phenomena have a common origin that must be associated with the occurrence of strong electrostatic interactions at the interface.
Sustainable Electrical Energy Storage through the Ferrocene/Ferrocenium Redox Reaction in Aprotic Electrolyte
Dr. Yu Zhao, Yu Ding, Dr. Jie Song, Dr. Gang Li, Prof. Guangbin Dong, Prof. John B. Goodenough and Prof. Guihua Yu
The redox couple ferrocene/ferrocenium is applied for the construction of a liquid cathode Li-ion redox battery for electrical energy storage. The redox reaction is highly reversible and efficient. Even after 250 full charge/discharge cycles the capacity maintains ca. 90 % of the initial value and the Coulombic efficiency reaches 98–100 %.
Exceptional Isotopic-Substitution Effect: Breakdown of Collective Proton Tunneling in Hexagonal Ice due to Partial Deuteration
Dr. Christof Drechsel-Grau and Prof. Dr. Dominik Marx
Ab initio simulations clarify the effects of H/D isotopic substitution on the mechanism of the collective tunneling of six protons within proton-ordered cyclic water hexamers that are contained in proton-disordered ice. At the transition state, isotopic substitution leads to a Zundel-like [HO⋅⋅⋅D⋅⋅⋅OH] complex with localized ionic defects and thus inhibits perfectly correlated proton tunneling.
Highly Diastereoselective and Enantiospecific Allylation of Ketones and Imines Using Borinic Esters: Contiguous Quaternary Stereogenic Centers
Dr. Jack L.-Y. Chen and Prof. Dr. Varinder K. Aggarwal
Goldilocks reactivity: 3,3-Disubstituted allylic borinic esters possess the perfect balance between reactivity and configurational stability to react with both ketones and ketimines, allowing facile access to adjacent quaternary stereocenters with full stereocontrol. Synthesis of all possible stereoisomers of a quaternary-quaternary motif is demonstrated. TFAA=trifluoroacetic anhydride.
A Lightweight Polymer Solar Cell Textile that Functions when Illuminated from Either Side
Zhitao Zhang, Xueyi Li, Guozhen Guan, Shaowu Pan, Zhengju Zhu, Dayong Ren and Prof. Huisheng Peng
A polymer solar cell textile has been developed by sandwiching a metal textile electrode between two ultrathin, transparent, and conducting carbon nanotube sheets. Because of its unique structure, the resulting solar cell textile shows the same energy conversion efficiency regardless of which side it is irradiated from. Furthermore, its energy conversion efficiencies were maintained even after 200 bending cycles.
Core/Shell Au/MnO Nanoparticles Prepared Through Controlled Oxidation of AuMn as an Electrocatalyst for Sensitive H2O2 Detection
Huiyuan Zhu, Aruna Sigdel, Dr. Sen Zhang, Dr. Dong Su, Zheng Xi, Dr. Qing Li and Prof. Shouheng Sun
Cell sensing: AuMn alloy nanoparticles were synthesized through hydride reduction of manganese acetylacetonate in the presence of Au nanoparticles and were subsequently converted into Au/MnO nanoparticles through air annealing. The Au/MnO nanoparticles are active catalysts for the electrochemical reduction of H2O2 and can be used to measure the H2O2 levels from different types of cells for cancer detection.
Long-Lived Trifluoromethanide Anion: A Key Intermediate in Nucleophilic Trifluoromethylations
Prof. Dr. G. K. Surya Prakash, Dr. Fang Wang, Zhe Zhang, Prof. Dr. Ralf Haiges, Dr. Martin Rahm, Prof. Dr. Karl O. Christe, Dr. Thomas Mathew and Prof. Dr. George A. Olah
Rather persistent: For more than 60 years, the trifluoromethanide anion has been widely believed to exist only as an extremely transient species in the condensed phase, and to undergo swift decomposition to difluorocarbene and fluoride. The trifluoromethanide anion has now been successfully prepared, observed, and characterized for the first time in solution. Contrary to previous assumptions, the anion possesses considerable lifetime at subambient temperatures.
Chiral Amine Synthesis Using ω-Transaminases: An Amine Donor that Displaces Equilibria and Enables High-Throughput Screening
Dr. Anthony P. Green, Prof. Nicholas J. Turner and Dr. Elaine O'Reilly
ω-Transaminases (ω-TA) are employed as biocatalysts in a simple and efficient process for the synthesis of chiral amines. A dual-function diamine donor (ortho-xylylenediamine) serves to displace challenging reaction equilibria towards product formation whilst generating intensely colored by-products, which have allowed the development of liquid-phase and colony-based assays.
Reconfigurable Swarms of Nematic Colloids Controlled by Photoactivated Surface Patterns
Sergi Hernàndez-Navarro, Dr. Pietro Tierno, Prof. Joan Anton Farrera, Prof. Jordi Ignés-Mullol and Prof. Francesc Sagués
Swarming into focus: The assembly and transport of large ensembles of colloidal particles or droplets that are dispersed in a film of anisotropic fluid can be directly controlled by means of AC electrophoresis. Individual or collective particle steering is independently achieved by elastic modulation of the host nematic liquid crystal on a photosensitive confining surface.
Decay of FeV Nitride Complexes by a N–N Bond Coupling Reaction in Solution: A Combined Spectroscopic and Theoretical Analysis
Oliver Krahe, Eckhard Bill, and Frank Neese*
Cryogenically trapped FeV–nitride complexes with cyclam-based ligands were found to decay by bimolecular reactions, forming exclusively FeII compounds. Characterization of educts and products by Mössbauer spectroscopy, mass spectrometry, and spectroscopy-oriented DFT calculations showed that the reaction mechanism is reductive nitride coupling and release of dinitrogen (2FeV≡NFeII-N=N-FeII2FeII+N2). The reaction pathways, representing an "inverse" of the Haber–Bosch reaction, were computationally explored in detail, also to judge the feasibility that the converse would yield catalytically competent FeV(N). Implications for the photolytic cleavage of FeIII–azides used to generate high-valent Fe nitrides could be discussed.
Received March 20, 2014, published online May 18, 2014, DOI: 10.1002/anie.201403402 – read now.
Did you read this article? Was it important to you? Let us know...
Rate Coefficients of Criegee Intermediate (CH2OO and CH3CHOO) Reactions with Formic and Acetic Acid Are Close to Their Collision Limit: Direct Kinetics Measurements and Atmospheric Implications
Oliver Welz, Arkke J. Eskola, Leonid Sheps, Brandon Rotavera, John D. Savee, Adam M. Scheer, David L. Osborn, Douglas Lowe, A. Murray Booth, Ping Xiao, M. Anwar H. Khan, Carl J. Percival,* Dudley E. Shallcross,* and Craig A. Taatjes*
Rate coefficients for reactions of Criegee intermediates (carbonyl oxides, CI) with organic acids are in excess of 1x10-10 cm3 s-1, suggesting that reaction with carboxylic acids is a substantially more important loss process for CI than has been assumed. Implementing these rate coefficients in global atmospheric models shows that reactions between CI and organic acids make a substantial contribution to removal of these acids in terrestrial equatorial areas and in other regions where high CI concentrations occur such as high northern latitudes, and implies that sources of acids in these areas are larger than previously recognized.
Received January 28, 2014, published online March 25, 2014, DOI: 10.1002/anie.201400964 – read now.
Did you read this article? Was it important to you? Let us know...