bluuebunny/crossref_metadata_2025 huggingface dataset:
Reexamining ultrafiltration and solute transport in groundwater
Authors: Neuzil C. E. , Person Mark
Published: May 2017

Geologic ultrafiltration—slowing of solutes with respect to flowing groundwater—poses a conundrum: it is consistently observed experimentally in clay‐rich lithologies, but has been difficult to identify in subsurface data. Resolving this could be important for clarifying clay and shale transport properties at large scales as well as interpreting solute and isotope patterns for applications ranging from nuclear waste repository siting to understanding fluid transport in tectonically active environments. Simulations of one‐dimensional NaCl transport across ultrafiltering clay membrane strata constrained by emerging data on geologic membrane properties showed different ultrafiltration effects than have often been envisioned. In relatively high‐permeability advection‐dominated regimes, salinity increases occurred mostly within membrane units while their effluent salinity initially fell and then rose to match solute delivery. In relatively low‐permeability diffusion‐dominated regimes, salinity peaked at the membrane upstream boundary and effluent salinity remained low. In both scenarios, however, only modest salinity changes (up to ∼3 g L−1) occurred because of self‐limiting tendencies; membrane efficiency declines as salinity rises, and although sediment compaction increases efficiency, it is also decreases permeability and allows diffusive transport to dominate. It appears difficult for ultrafiltration to generate brines as speculated, but widespread and less extreme ultrafiltration effects in the subsurface could be unrecognized. Conditions needed for ultrafiltration are present in settings that include topographically‐driven flow systems, confined aquifer systems subjected to injection or withdrawal, compacting basins, and accretionary complexes.
Immune and myodegenerative pathomechanisms in inclusion body myositis
Authors: Keller Christian W. , Schmidt Jens , Lünemann Jan D.
Published: May 2017

Inclusion Body Myositis (IBM) is a relatively common acquired inflammatory myopathy in patients above 50 years of age. Pathological hallmarks of IBM are intramyofiber protein inclusions and endomysial inflammation, indicating that both myodegenerative and inflammatory mechanisms contribute to its pathogenesis. Impaired protein degradation by the autophagic machinery, which regulates innate and adaptive immune responses, in skeletal muscle fibers has recently been identified as a potential key pathomechanism in IBM. Immunotherapies, which are successfully used for treating other inflammatory myopathies lack efficacy in IBM and so far no effective treatment is available. Thus, a better understanding of the mechanistic pathways underlying progressive muscle weakness and atrophy in IBM is crucial in identifying novel promising targets for therapeutic intervention. Here, we discuss recent insights into the pathomechanistic network of mutually dependent inflammatory and degenerative events during IBM.
Effect of Fatigue, Older Age, Higher Body Mass Index, and Female Sex on Disability in Early Rheumatoid Arthritis in the Treatment‐to‐Target Era
Authors: Twigg Sarah , Hensor Elizabeth M. A. , Freeston Jane , Tan Ai Lyn , Emery Paul , Tennant Alan , Morgan Ann W. ,   the YEAR and IACON Consortia
Published: May 2017

Objective

To compare disease activity and disability over 2 years in early rheumatoid arthritis (RA) before and after implementation of treat‐to‐target therapy and identify predictors of adverse outcome.

Methods

The Yorkshire Early Arthritis Register (YEAR) recruited 725 patients with early RA between 2002 and 2009, treated with a step‐up approach. The Inflammatory Arthritis Continuum study (IACON) recruited cases between 2010 and 2014 and treated to target. A total of 384 IACON cases met 2010 American College of Rheumatology/European League Against Rheumatism criteria. Latent growth curves of change in Disease Activity Score in 28 joints (DAS28) and the Health Assessment Questionnaire (HAQ) were compared between YEAR and IACON. Latent class growth analysis identified trajectories of change. Baseline predictors of trajectories were identified using logistic regression.

Results

The mean DAS28 over 2 years was lower in IACON than in YEAR. Latent trajectories of HAQ change in YEAR were high stable (21% of cohort), moderate reducing (35%), and low reducing (44%). Only moderate reducing (66%) and low reducing (34%) were seen in IACON. In both cohorts, female sex and fatigue predicted adverse HAQ trajectories (high stable and moderate reducing). Odds ratios (ORs) for moderate reducing compared to low reducing for women were 2.58 (95% confidence interval [95% CI] 1.69, 4.49) in YEAR and 5.81 (95% CI 2.44, 14.29) in IACON. ORs per centimeter fatigue visual analog score were 1.13 (95% CI 1.07, 1.20) in YEAR and 1.16 (95% CI 1.12, 1.20) in IACON.

Conclusion

Treat‐to‐target therapy gave more favorable trajectories of change in DAS28 and HAQ, but adverse HAQ trajectory was more likely in women with greater fatigue, suggesting such patients would benefit from interventions to improve function as well as reduce inflammation.
High‐Performance Near‐IR Photodetector Using Low‐Bandgap MA0.5FA0.5Pb0.5Sn0.5I3 Perovskite
Authors: Xu Xiaobao , Chueh Chu‐Chen , Jing Peifeng , Yang Zhibin , Shi Xueliang , Zhao Ting , Lin Lih Y. , Jen Alex K.‐Y.
Published: May 2017

Photodetectors with ultrafast response are explored using inorganic/organic hybrid perovskites. High responsivity and fast optoelectronic response are achieved due to the exceptional semiconducting properties of perovskite materials. However, most of the perovskite‐based photodetectors exploited to date are centered on Pb‐based perovskites, which only afford spectral response across the visible spectrum. This study demonstrates a high‐performance near‐IR (NIR) photodetector using a stable low‐bandgap Sn‐containing perovskite, (CH3NH3)0.5(NH2CHNH2)0.5Pb0.5Sn0.5I3 (MA0.5FA0.5Pb0.5Sn0.5I3), which is processed with an antioxidant additive, ascorbic acid (AA). The addition of AA effectively strengthens the stability of Sn‐containing perovskite against oxygen, thereby significantly inhibiting the leakage current. Consequently, the derived photodetector shows high responsivity with a detectivity of over 1012 Jones ranging from 800 to 970 nm. Such low‐cost, solution processable NIR photodetectors with high performance show promising potential for future optoelectronic applications.
Fully Stable and Homogeneous Lyotropic Liquid Crystal Alignment on Anisotropic Surfaces
Authors: van der Asdonk Pim , Collings Peter J. , Kouwer Paul H. J.
Published: May 2017

Lyotropic chromonic liquid crystals have great potential in both biosensing and optical devices due to their biocompatible nature and strong optical characteristics. These applications, however, demand a homogeneous and stable alignment on anisotropic surfaces, a challenge that, so far, has not been solved adequately. In this work, it is shown how to drastically increase the quality of in‐plane alignment and stability of these liquid crystals on conventional rubbed polyimide substrates by the addition of a small amount of a nonionic surfactant. Samples with surfactant show excellent alignment that is stable for months, while control samples without surfactant show much poorer alignment that further deteriorates in days. Also, well‐aligned dry films of chromonics can be prepared following this approach. It is demonstrated how to obtain high‐quality alignment by controlling the concentration and the nature of the surfactant, in particular its molecular structure and hydrophilic/lipophilic balance (HLB value) and other critical parameters are discussed. It is believed that this approach may very well be essential for advancing the applicability of these water‐based, biocompatible, and often highly dichroic materials for a wide range of uses.
Topography‐Guided Control of Local Migratory Behaviors and Protein Expression of Cancer Cells
Authors: Shin Jung‐Youn , Kim Hong Nam , Bhang Suk Ho , Yoon Jeong‐Kee , Suh Kahp‐Yang , Jeon Noo Li , Kim Byung‐Soo
Published: May 2017

In vivo cancer cell migration and invasion are directed by biophysical guidance mechanisms such as pre‐existing microtracks and basement membrane extracellular matrices. Here, this paper reports the correlation of the local migratory behavior of cancer cells and the biochemical signal expression using the topography that can guide or inhibit cell behaviors. To this end, the local apparent migration and the protein expression level are investigated with respect to the topographical feature size (flat, nanoline, and microline) and orientation (microline, microconcentric, and microradial) with the collectively migrating (A431) and individually migrating (MDA‐MB‐231 and U‐87‐MG) cancer cells. The results show that the migration and the protein expression of focal adhesion kinase, rho‐associated protein kinase, and extracellular signal‐regulated kinase are localized in the periphery of cell colony. Furthermore, the inhibition of migratory behavior at the periphery recues the protein expression, while the guidance of migration enhances the aforementioned protein expression. The results may imply the employ of biophysical inhibitory factors can help to control invasiveness of cancer cells during the progression state.
Self‐Assembled Nanoparticles from Phenolic Derivatives for Cancer Therapy
Authors: Dai Yunlu , Guo Junling , Wang Ting‐Yi , Ju Yi , Mitchell Andrew J. , Bonnard Thomas , Cui Jiwei , Richardson Joseph J. , Hagemeyer Christoph E. , Alt Karen , Caruso Frank
Published: May 2017

Therapeutic nanoparticles hold clinical promise for cancer treatment by avoiding limitations of conventional pharmaceuticals. Herein, a facile and rapid method is introduced to assemble poly(ethylene glycol) (PEG)‐modified Pt prodrug nanocomplexes through metal‐polyphenol complexation and combined with emulsification, which results in ≈100 nm diameter nanoparticles (PtP NPs) that exhibit high drug loading (0.15 fg Pt per nanoparticle) and low fouling properties. The PtP NPs are characterized for potential use as cancer therapeutics. Mass cytometry is used to quantify uptake of the nanoparticles and the drug concentration in individual cells in vitro. The PtP NPs have long circulation times, with an elimination half‐life of ≈18 h in healthy mice. The in vivo antitumor activity of the PtP NPs is systematically investigated in a human prostate cancer xenograft mouse model. Mice treated with the PtP NPs demonstrate four times better inhibition of tumor growth than either free prodrug or cisplatin. This study presents a promising strategy to prepare therapeutic nanoparticles for biomedical applications.
Low‐Threshold Whispering Gallery Mode Lasing from Self‐Assembled Microspheres of Single‐Sort Conjugated Polymers
Authors: Kushida Soh , Okada Daichi , Sasaki Fumio , Lin Zhan‐Hong , Huang Jer‐Shing , Yamamoto Yohei
Published: May 2017

Low‐threshold organic microlasers are demanded for advanced optical applications such as nano/micrometer scale memory, sensing, and communication tools, and further valuable for future electrically driven laser applications. In this paper, it is demonstrated that various highly fluorescent conjugated polymers self‐assemble to form single‐component microspheres that exhibit, upon femtosecond pumping to a single microsphere, whispering gallery mode (WGM) lasing with blue, green, and red emission colors. In particular, the microsphere consisting of polyfluorene shows the lowest threshold fluence as low as 1.5 µJ cm−2 and high photostability against successive pumping of >105 pulse. The threshold fluence is further reduced by one fourth (0.37 µJ cm−2) by mounting the microspheres on an Ag‐coated substrate, where a mirror effect of the Ag layer enhances efficiency of the photoluminescence confinement with a minor effect of plasmonic near‐field. Considering the intrinsic charge injection and transport properties, π‐conjugated polymer microsphere resonators will be possible materials for electrically pumped WGM luminescence.
Gold(I)‐catalyzed synthesis of dihydrodibenzoquinolizinium salts
Authors: Marien Niels , Verniest Guido
Published: May 2017

A gold‐catalyzed cyclization of 1‐alkynyl‐2‐aryl tetrahydroisoquinolines is described for the synthesis of novel dihydrodibenzoquinolizinium salts. The reaction mechanism is likely to involve a 6‐endo‐dig cyclization and subsequent oxidation by air to give a relatively stable arylgold intermediate. This gold species undergoes protodeauration under acidic conditions to afford the title compounds. An NMR study was performed to gain further evidence and insight on the presence of the arylgold intermediate and the reaction mechanism.

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Transition‐Metal (Fe, Co, Ni) Based Metal‐Organic Frameworks for Electrochemical Energy Storage
Authors: Zheng Shasha , Li Xinran , Yan Bingyi , Hu Qin , Xu Yuxia , Xiao Xiao , Xue Huaiguo , Pang Huan
Published: May 2017

Transition‐metal (Fe, Co, Ni) based metal‐organic framework materials with controllable structures, large surface areas and adjustable pore sizes have attracted wide research interest for use in next‐generation electrochemical energy‐storage devices. This review introduces the synthesis of transition‐metal (Fe, Co, Ni) based metal‐organic frameworks and their derivatives with the focus on their application in supercapacitors and batteries.
Anion Doping: A New Strategy for Developing High‐Performance Perovskite‐Type Cathode Materials of Solid Oxide Fuel Cells
Authors: Zhang Zhenbao , Zhu Yinlong , Zhong Yijun , Zhou Wei , Shao Zongping
Published: May 2017

Overcoming the sluggish activity of cathode materials is critical to realizing the wide‐spread application of intermediate‐temperature solid oxide fuel cells. Herein, a new way is reported to tune the performance of perovskite‐type materials as oxygen reduction electrodes by embedding anions (F−) in oxygen sites. The obtained perovskite oxyfluorides SrFeO3−σ−δFσ and SrFe0.9Ti0.1O3−σ−δFσ (σ = 0.05 and 0.10) show improved electrocatalytic activity compared to their parent oxides, achieving area specific resistance values of 0.875, 0.393, and 0.491 Ω cm2 for SrFeO3−δ, SrFeO2.95−δF0.05, and SrFeO2.90−δF0.10, respectively, at 600 °C in air. Such improved performance is a result of the improved bulk diffusion and surface exchange properties due to anion doping. Moreover, favorable stability in performance is also demonstrated for the F− anion‐doped perovskites as oxygen reduction electrodes at 650 °C for a test period of ≈200 h. A combination of anion doping and cation doping may provide a highly attractive strategy for the future development of cathode materials.
A Metal‐Free and Biotically Degradable Battery for Portable Single‐Use Applications
Authors: Esquivel Juan Pablo , Alday Perla , Ibrahim Omar A. , Fernández Belén , Kjeang Erik , Sabaté Neus
Published: May 2017

This article presents a new approach for environmentally benign, low‐cost batteries intended for single‐use applications. The proposed battery is designed and fabricated using exclusively organic materials such as cellulose, carbon, and wax and features an integrated quinone‐based redox chemistry to generate electricity within a compact form factor. This primary capillary flow battery is activated by the addition of a liquid sample and has shown continuous operation up to 100 min with an output voltage that can be conveniently scaled to match the voltage needs of portable electronic devices (1.5–3.0 V). Once depleted, the battery can be disposed of without the need for any recycling facility, as its components are nontoxic and shown to be biotically degradable in a standardized test. The practical utility of the battery is demonstrated by direct substitution of a lithium ion coin cell in a diagnostic application.
Substratspezifische Analyse von Aminosäuren mit Sensoren für d/ l‐Cystein: umfassende stereochemische Untersuchungen in wässriger Lösung
Authors: Thanzeel F. Yushra , Wolf Christian
Published: May 2017

Das Auftreten von d‐Aminosäuren in Säugern und im Menschen ist von großer Bedeutung für die Lebenswissenschaften. d/l‐Aminosäuremischungen spielen eine Schlüsselrolle bei der menschlichen Physiologie und Pathologie; daher ist die Einführung künstlicher Rezeptoren für die Echtzeitquantifizierung der Konzentration und des d/l‐Verhältnisses von Aminosäuren vielversprechend für das Studium biologischer Prozesse und die Diagnose sowie Behandlung von Krankheiten. Die hier vorgestellte Detektionsmethode ist kompatibel mit wässrigen Lösungen und ermöglicht die rasche Bestimmung der absoluten Konfiguration, des ee‐Werts und der Gesamtmenge von Cystein bei mikromolaren Konzentrationen. Die Methode beruht auf schnellen UV‐ und CD‐Messungen, die akkurate stereochemische Informationen mit Proben über einen weiten Konzentrationsbereich und mit stark unterschiedlichen d/l‐Cysteinverhältnissen in simulierten Körperflüssigkeiten liefern. Konkurrenzexperimente zeigen, dass andere Aminosäuren und Biothiole die gezielte Cysteinanalyse nicht stören.
Polyoxometalate‐Engineered Building Blocks with Gold Cores for the Self‐Assembly of Responsive Water‐Soluble Nanostructures
Authors: Wang Yizhan , Raula Manoj , Wang Yifeng , Zeiri Offer , Chakraborty Sourav , Gan‐Or Gal , Gadot Eyal , Weinstock Ira A.
Published: May 2017

The controlled assembly of gold nanoparticles (AuNPs) with the size of quantum dots into predictable structures is extremely challenging as it requires the quantitatively and topologically precise placement of anisotropic domains on their small, approximately spherical surfaces. We herein address this problem by using polyoxometalate leaving groups to transform 2 nm diameter gold cores into reactive building blocks with hydrophilic and hydrophobic surface domains whose relative sizes can be precisely tuned to give dimers, clusters, and larger micelle‐like organizations. Using cryo‐TEM imaging and 1H DOSY NMR spectroscopy, we then provide an unprecedented “solution‐state” picture of how the micelle‐like structures respond to hydrophobic guests by encapsulating them within 250 nm diameter vesicles whose walls are comprised of amphiphilic AuNP membranes. These findings provide a versatile new option for transforming very small AuNPs into precisely tailored building blocks for the rational design of functional water‐soluble assemblies.
A Carbon Dioxide Bubble‐Induced Vortex Triggers Co‐Assembly of Nanotubes with Controlled Chirality
Authors: Zhang Ling , Zhou Laicheng , Xu Na , Ouyang Zhenjie
Published: May 2017

It is challenging to prepare co‐organized nanotube systems with controlled nanoscale chirality in an aqueous liquid flow field. Such systems are responsive to a bubbled external gas. A liquid vortex induced by bubbling carbon dioxide (CO2) gas was used to stimulate the formation of nanotubes with controlled chirality; two kinds of achiral cationic building blocks were co‐assembled in aqueous solution. CO2‐triggered nanotube formation occurs by formation of metastable intermediate structures (short helical ribbons and short tubules) and by transition from short tubules to long tubules in response to chirality matching self‐assembly. Interestingly, the chirality sign of these assemblies can be selected for by the circulation direction of the CO2 bubble‐induced vortex during the co‐assembly process.
Highly Rechargeable Lithium‐CO2 Batteries with a Boron‐ and Nitrogen‐Codoped Holey‐Graphene Cathode
Authors: Qie Long , Lin Yi , Connell John W. , Xu Jiantie , Dai Liming
Published: May 2017

Metal‐air batteries, especially Li‐air batteries, have attracted significant research attention in the past decade. However, the electrochemical reactions between CO2 (0.04 % in ambient air) with Li anode may lead to the irreversible formation of insulating Li2CO3, making the battery less rechargeable. To make the Li‐CO2 batteries usable under ambient conditions, it is critical to develop highly efficient catalysts for the CO2 reduction and evolution reactions and investigate the electrochemical behavior of Li‐CO2 batteries. Here, we demonstrate a rechargeable Li‐CO2 battery with a high reversibility by using B,N‐codoped holey graphene as a highly efficient catalyst for CO2 reduction and evolution reactions. Benefiting from the unique porous holey nanostructure and high catalytic activity of the cathode, the as‐prepared Li‐CO2 batteries exhibit high reversibility, low polarization, excellent rate performance, and superior long‐term cycling stability over 200 cycles at a high current density of 1.0 A g−1. Our results open up new possibilities for the development of long‐term Li‐air batteries reusable under ambient conditions, and the utilization and storage of CO2.
Crystal‐Packing‐Driven Enrichment of Atropoisomers
Authors: Sharafi Mona , Campbell Joseph P. , Rajappan Sinu C. , Dudkina Natavan , Gray Danielle L. , Woods Toby J. , Li Jianing , Schneebeli Severin T.
Published: May 2017

Crystal‐packing forces can have a significant impact on the relative stabilities of different molecules and their conformations. The magnitude of such effects is, however, not yet well understood. Herein we show, that crystal packing can completely overrule the relative stabilities of different stereoisomers in solution. Heating of atropoisomers (i.e. “frozen‐out” conformational isomers) in solution leads to complex mixtures. In contrast, solid‐state heating selectively amplifies minor (<25 mole %) components of these solution‐phase mixtures. We show that this heating strategy is successful for compounds with up to four rotationally hindered σ bonds, for which a single stereoisomer out of seven can be amplified selectively. Our results demonstrate that common supramolecular interactions—for example, [methyl⋅⋅⋅π] coordination and [C−H⋅⋅⋅O] hydrogen bonding—can readily invert the relative thermodynamic stabilities of different molecular conformations. These findings open up potential new avenues to control the folding of macromolecules.
Synthesis of an Aluminum Hydroxide Octamer through a Simple Dissolution Method
Authors: Perkins Cory K. , Eitrheim Eric S. , Fulton Brantly L. , Fullmer Lauren B. , Colla Christopher A. , Park Deok‐Hie , Oliveri Anna F. , Hutchison James E. , Nyman May , Casey William H. , Forbes Tori Z. , Johnson Darren W. , Keszler Douglas A.
Published: May 2017

Multimeric oxo‐hydroxo Al clusters function as models for common mineral structures and reactions. Cluster research, however, is often slowed by a lack of methods to prepare clusters in pure form and in large amounts. Herein, we report a facile synthesis of the little known cluster Al8(OH)14(H2O)18(SO4)5 (Al8) through a simple dissolution method. We confirm its structure by single‐crystal X‐ray diffraction and show by 27Al NMR spectroscopy, electrospray‐ionization mass spectrometry, and small‐ and wide‐angle X‐ray scattering that it also exists in solution. We speculate that Al8 may form in natural water systems through the dissolution of aluminum‐containing minerals in acidic sulfate solutions, such as those that could result from acid rain or mine drainage. Additionally, the dissolution method produces a discrete Al cluster on a scale suitable for studies and applications in materials science.
Selektive Si‐C(sp3)‐Bindungsspaltung in (Aminomethyl)silanen durch carbanionische Nucleophile und ihr stereochemischer Verlauf
Authors: Koller Stephan G. , Bauer Jonathan O. , Strohmann Carsten
Published: May 2017

Die Nutzbarmachung von Tetraorganosilanen durch gezielte Spaltung einer Si‐C‐Bindung ist noch immer eine anspruchsvolle Aufgabe. Nun wurde ein neuer Typ von Si‐C(sp3)‐Bindungsspaltungen in stabilen (Aminomethyl)silanen mit gewöhnlichen Organolithiumreagentien als Nucleophilen gefunden. Als Abgangsgruppen eignen sich Benzyl‐, Allyl‐ und Phenylthiomethylgruppen. Ein β‐ständiges Donoratom und polare Lösungsmittel sind essenziell für die Reaktion. Durch eine einfache Änderung der Reaktionsbedingungen kann zwischen einer α‐Deprotonierung und einer Substitution umgeschaltet werden. Anhand eines siliciumchiralen Benzylsilans wurde der stereochemische Verlauf der Reaktion aufgeklärt. Die neue Umsetzung verläuft stereospezifisch unter Inversion der Konfiguration und eignet sich für eine zielgerichtete Synthese schwer zugänglicher, enantiomerenreiner Tetraorganosilane. Quantenchemische Rechnungen liefern einen Einblick in den Mechanismus der neuartigen Substitution.
Structural Dynamics upon Photoexcitation in a Spin Crossover Crystal Probed with Femtosecond Electron Diffraction
Authors: Jiang Yifeng , Liu Lai Chung , Müller‐Werkmeister Henrike M. , Lu Cheng , Zhang Dongfang , Field Ryan L. , Sarracini Antoine , Moriena Gustavo , Collet Eric , Miller R. J. Dwayne
Published: May 2017

Photoexcitation of spin crossover (SCO) complexes can trigger extensive electronic spin transitions and transformation of molecular structure. However, the precise nature of the associated ultrafast structural dynamics remains elusive, especially in the solid state. Here, we studied a single‐crystal SCO material with femtosecond electron diffraction (FED). The unique capability of FED allows us to directly probe atomic motions and to track ultrafast structural changes within a crystal lattice. By monitoring the time‐dependent changes of the Bragg reflections, we observed the formation of a photoinduced structure similar to the thermally induced high‐spin state. The data and refinement calculations indicate the global structural reorganization within 2.3 ps, as the metal–ligand bond distribution narrows during intramolecular vibrational energy redistribution (IVR) driving the intermolecular rearrangement. Three independent dynamical group are identified to model the structural dynamics upon photoinduced SCO.
Durch Cp*Fe‐Fragmente stabilisierte, Arsen‐reiche Polyarsenide
Authors: Schmidt Monika , Konieczny David , Peresypkina Eugenia V. , Virovets Alexander V. , Balázs Gabor , Bodensteiner Michael , Riedlberger Felix , Krauss Hannes , Scheer Manfred
Published: May 2017

Die Untersuchung der Redoxchemie von [Cp*Fe(η5‐As5)] (1) (Cp*=η5‐C5Me5) mittels Cyclovoltammetrie ergab ein Redoxverhalten, das jenem des leichteren Verwandten [Cp*Fe(η5‐P5)] ähnelt. Die anschließende chemische Reduktion von 1 durch KH führt zur Bildung eines Gemisches von Produkten mit neuartigen Asn‐Gerüsten (n=bis zu 18), die lediglich durch [Cp*Fe]‐Fragmente stabilisiert werden. Dazu gehören der Arsen‐arme Tripeldeckerkomplex [K(dme)2][{Cp*Fe(μ,η2:2‐As2)}2] (2) und die Arsen‐reichen Komplexe [K(dme)3]2[(Cp*Fe)2(μ,η4:4‐As10)] (3), [K(dme)2]2[(Cp*Fe)2(μ,η2:2:2:2‐As14)] (4) sowie [K(dme)3]2[(Cp*Fe)4(μ4,η4:3:3:2:2:1:1‐As18)] (5). 4 und der Polyarsenidkomplex 5 enthalten die bisher größten publizierten anionischen Asn‐Liganden. Die Komplexe 2–5 wurden durch Einkristall‐Röntgenstrukturanalyse, 1H‐NMR‐Spektroskopie, EPR‐Spektroskopie (2) und Massenspektrometrie charakterisiert. Darüber hinaus zeigten DFT‐Rechnungen eine schnelle Dimerisierung des mutmaßlich zuerst gebildeten Intermediates [Cp*Fe(η5‐As5)]− zum Dianion [(Cp*Fe)2(μ,η4:4‐As10)]2−.
Exploring the Molecular Growth of Two Gigantic Half‐Closed Polyoxometalate Clusters {Mo180} and {Mo130Ce6}
Authors: Xuan Weimin , Pow Robert , Long De‐Liang , Cronin Leroy
Published: May 2017

Understanding the process of the self‐assembly of gigantic polyoxometalates and their subsequent molecular growth, by the addition of capping moieties onto the oxo‐frameworks, is critical for the development of the designed assembly of complex high‐nuclearity cluster species, yet such processes remain far from being understood. Herein we describe the molecular growth from {Mo150} and {Mo120Ce6} to afford two half‐closed gigantic molybdenum blue clusters {Mo180} (1) and {Mo130Ce6} (2), respectively. Compound 1 features a hat‐shaped structure with the parent wheel‐shaped {Mo150} being capped by a {Mo30} unit on one side. Similarly, 2 exhibits an elliptical lanthanide‐doped wheel {Mo120Ce6} that is sealed by a {Mo10} unit on one side. Moreover, the observation of the parent uncapped {Mo150} and {Mo120Ce6} clusters as minor products during the synthesis of 1 and 2 strongly suggests that the molecular growth process can be initialized from {Mo150} and {Mo120Ce6} in solution, respectively.
Iridium‐Catalyzed Formyl‐Selective Deuteration of Aldehydes
Authors: Kerr William J. , Reid Marc , Tuttle Tell
Published: May 2017

We report the first direct catalytic method for formyl‐selective deuterium labeling of aromatic aldehydes under mild conditions, using an iridium‐based catalyst designed to favor formyl over aromatic C−H activation. A good range of aromatic aldehydes is selectively labeled, and a one‐pot labeling/olefination method is also described. Computational studies support kinetic product control over competing aromatic labeling and decarbonylation pathways.
Synthesis of β‐Lactams by Palladium(0)‐Catalyzed C(sp3)−H Carbamoylation
Authors: Dailler David , Rocaboy Ronan , Baudoin Olivier
Published: May 2017

A general and user‐friendly synthesis of β‐lactams is reported that makes use of Pd0‐catalyzed carbamoylation of C(sp3)−H bonds, and operates under stoichiometric carbon monoxide in a two‐chamber reactor. This reaction is compatible with a range of primary, secondary and activated tertiary C−H bonds, in contrast to previous methods based on C(sp3)−H activation. In addition, the feasibility of an enantioselective version using a chiral phosphonite ligand is demonstrated. Finally, this method can be employed to synthesize valuable enantiopure free β‐lactams and β‐amino acids.
meso‐Cumulenic 2H‐Corroles from meso‐Ethynyl‐3H‐corroles
Authors: Ueta Kento , Naoda Koji , Ooi Shota , Tanaka Takayuki , Osuka Atsuhiro
Published: May 2017

Alkynyl‐substituted 3H‐corrole 9 a was converted to [3]cumulenic 2H‐corrole 10 a by treatment with trimethylsilyl chloride (TMSCl), and 1,3‐butadiyne‐bridged 3H‐corrole dimer 11 b was transformed into [5]cumulene‐bridged 2H‐corrole dimer 12 b by oxidation with PbO2. Both 10 a and 12 b were metalated to form ZnII complexes 10 a‐Zn and 12 b‐Zn. The structures of 10 a‐Zn and 12 b‐Zn show planar conformations with bond‐length alternations that are analogous to those of tetraaryl [n]cumulenes. The cumulenic corrole dimers 12 b and 12 b‐Zn display large NIR absorption bands in the range of 700–1400 nm (maximum ϵ≈1.0×105 m−1 cm−1) owing to the effective π‐conjugation between the two corrole units through the [5]cumulene bridge.
A Dual Palladium and Copper Hydride Catalyzed Approach for Alkyl–Aryl Cross‐Coupling of Aryl Halides and Olefins
Authors: Friis Stig D. , Pirnot Michael T. , Dupuis Lauren N. , Buchwald Stephen L.
Published: May 2017

We report an efficient means of sp2–sp3 cross coupling for a variety of terminal monosubstituted olefins with aryl electrophiles using Pd and CuH catalysis. In addition to its applicability to a range of aryl bromide substrates, this process was also suitable for electron‐deficient aryl chlorides, furnishing higher yields than the corresponding aryl bromides in these cases. The optimized protocol does not require the use of a glovebox and employs air‐stable Cu and Pd complexes as precatalysts. A reaction on 10 mmol scale further highlighted the practical utility of this protocol. Employing a similar protocol, a series of cyclic alkenes were also examined. Cyclopentene was shown to undergo efficient coupling under these conditions. Lastly, deuterium‐labeling studies indicate that deuterium scrambling does not take place in this sp2‐sp3 cross coupling, implying that β‐hydride elimination is not a significant process in this transformation.
Isomerenselektive Erzeugung und spektroskopische Charakterisierung der Picolyl‐Radikale
Authors: Reusch Engelbert , Holzmeier Fabian , Constantinidis Philipp , Hemberger Patrick , Fischer Ingo
Published: May 2017

Stickstoff‐haltige resonanzstabilisierte Radikale wie Picolyl spielen eine wichtige Rolle in Verbrennungsprozessen und in der Astrochemie. Sie wurden jedoch bislang kaum untersucht, da es schwierig ist, sie isomerenselektiv zu erzeugen. Schwellenphotoelektronenspektren der drei Isomere des Picolyl‐Radikals, C6H6N, wurden mit Synchrotronstrahlung aufgenommen. Die Radikale wurden selektiv durch Pyrolyse aus Aminomethylpyridinen hergestellt. Ionisierungsenergien von 7.70, 7.59 und 8.01 eV wurden für 2‐, 3‐ bzw. 4‐Picolyl gemessen. Die beobachtete Schwingungsstruktur wurde einer Deformationsschwingung des aromatischen Rings zugeordnet. Die gewonnenen spektroskopischen Daten ermöglichen es, die verschiedenen Picolyl‐Isomere selektiv nachzuweisen, beispielsweise in der Flammenanalytik.
Enantioselective Synthesis of Tetrahydroquinolines by Borrowing Hydrogen Methodology: Cooperative Catalysis by an Achiral Iridacycle and a Chiral Phosphoric Acid
Authors: Lim Ching Si , Quach Thanh Truong , Zhao Yu
Published: May 2017

We report herein the highly enantioselective synthesis of 2‐substituted tetrahydroquinolines through borrowing hydrogen, a process recognized for its environmentally benign and atom‐economical nature. The use of an achiral iridacycle complex in combination with a chiral phosphoric acid as catalysts was the key to the development of this highly efficient and enantioselective transformation.
Selective Si−C(sp3) Bond Cleavage in (Aminomethyl)silanes by Carbanionic Nucleophiles and Its Stereochemical Course
Authors: Koller Stephan G. , Bauer Jonathan O. , Strohmann Carsten
Published: May 2017

Selective cleavage of a silicon–carbon bond in tetraorganosilanes is still a great challenge. A new type of Si−C(sp3) bond cleavage in bench‐stable (aminomethyl)silanes with common organolithium reagents as nucleophiles has now been identified. Suitable leaving groups are benzyl, allyl, and phenylthiomethyl groups. A β‐donor function and polar solvents are essential for the reaction. Simple switching between α‐deprotonation and substitution is possible through slight modifications of the reaction conditions. The stereochemical course of the reaction was elucidated by using a silicon‐chiral benzylsilane. The new transformation proceeds stereospecifically with inversion of configuration and can be used for the targeted synthesis of enantiomerically pure tetraorganosilanes, which are otherwise difficult to access. Quantum chemical calculations provided insight into the mechanism of the new substitution.
Manganese‐Catalyzed Sustainable Synthesis of Pyrroles from Alcohols and Amino Alcohols
Authors: Kallmeier Fabian , Dudziec Beata , Irrgang Torsten , Kempe Rhett
Published: May 2017

The development of reactions that convert alcohols into important chemical compounds saves our fossil carbon resources as alcohols can be obtained from indigestible biomass such as lignocellulose. The conservation of our rare noble metals is of similar importance, and their replacement by abundantly available transition metals, such as Mn, Fe, or Co (base or nonprecious metals), in key technologies such as catalysis is a promising option. Herein, we report on the first base‐metal‐catalyzed synthesis of pyrroles from alcohols and amino alcohols. The most efficient catalysts are Mn complexes stabilized by PN5P ligands whereas related Fe and Co complexes are inactive. The reaction proceeds under mild conditions at catalyst loadings as low as 0.5 mol %, and has a broad scope and attractive functional‐group tolerance. These findings may inspire others to use Mn catalysts to replace Ir or Ru complexes in challenging dehydrogenation reactions.
Arsenic‐Rich Polyarsenides Stabilized by Cp*Fe Fragments
Authors: Schmidt Monika , Konieczny David , Peresypkina Eugenia V. , Virovets Alexander V. , Balázs Gabor , Bodensteiner Michael , Riedlberger Felix , Krauss Hannes , Scheer Manfred
Published: May 2017

The redox chemistry of [Cp*Fe(η5‐As5)] (1, Cp*=η5‐C5Me5) has been investigated by cyclic voltammetry, revealing a redox behavior similar to that of its lighter congener [Cp*Fe(η5‐P5)]. However, the subsequent chemical reduction of 1 by KH led to the formation of a mixture of novel Asn scaffolds with n up to 18 that are stabilized only by [Cp*Fe] fragments. These include the arsenic‐poor triple‐decker complex [K(dme)2][{Cp*Fe(μ,η2:2‐As2)}2] (2) and the arsenic‐rich complexes [K(dme)3]2[(Cp*Fe)2(μ,η4:4‐As10)] (3), [K(dme)2]2[(Cp*Fe)2(μ,η2:2:2:2‐As14)] (4), and [K(dme)3]2[(Cp*Fe)4(μ4,η4:3:3:2:2:1:1‐As18)] (5). Compound 4 and the polyarsenide complex 5 are the largest anionic Asn ligand complexes reported thus far. Complexes 2–5 were characterized by single‐crystal X‐ray diffraction, 1H NMR spectroscopy, EPR spectroscopy (2), and mass spectrometry. Furthermore, DFT calculations showed that the intermediate [Cp*Fe(η5‐As5)]−, which is presumably formed first, undergoes fast dimerization to the dianion [(Cp*Fe)2(μ,η4:4‐As10)]2−.
Scandium‐Mediated Formation of a Bis(tetrahydropentalene)
Authors: Rausch Janek , Liebing Phil , Lorenz Volker , Hilfert Liane , Busse Sabine , Maichle‐Mössmer Caecilia , Edelmann Frank T.
Published: May 2017

The reactivity of Li[Sc(COT′′)2] (1; COT′′=1,4‐bis(trimethylsilyl)cyclooctatetraenyl) towards CoCl2 is considerably different from that of related lanthanide triple‐decker sandwich complexes. In addition to the expected triple‐decker complex Sc2(COT′′)3 (2), the complex Sc2{μ‐BTHP}(COT′′)2 (3) is formed, which comprises the novel BTHP2− ligand (BTHP2−=bis(3,5‐bis(trimethylsilyl)‐1,3a,6,6a‐tetrahydropentalene‐1‐yl)diide or bis(2,7‐bis(trimethylsilyl)bicyclo[3.3.0]octa‐2,7‐dien‐4‐yl)diide, C16H10(SiMe3)42−). The formation of 3 is likely facilitated by the fact that scandium prefers η8,η3 coordination rather than highly symmetric η8,η8 coordination, and the η3‐coordinated COT′′ ligand in 1 is activated owing to a loss of aromaticity. Acid hydrolysis of 3 leads to air‐stable H2BTHP (4).
Isomer‐Selective Generation and Spectroscopic Characterization of Picolyl Radicals
Authors: Reusch Engelbert , Holzmeier Fabian , Constantinidis Philipp , Hemberger Patrick , Fischer Ingo
Published: May 2017

Nitrogen‐containing resonance‐stabilized radicals such as the picolyl radical are important in combustion chemistry and astrochemistry. They have only been scarcely studied because an isomer‐selective generation is often difficult. Herein, we present threshold photoelectron spectra of the three picolyl radical isomers, C6H6N, that were obtained with synchrotron radiation. The radicals were selectively generated by flash pyrolysis from aminomethylpyridine precursors through deamination. Ionization energies of 7.70, 7.59, and 8.01 eV were determined for 2‐, 3‐, and 4‐picolyl, respectively. The observed vibrational structure was assigned to an in‐plane deformation mode of the aromatic ring. The spectroscopic insight gained in this study can be used to distinguish different picolyl isomers in on‐line combustion analysis, for example.
Intermolecular Charge‐Transfer Interactions Facilitate Two‐Photon Absorption in Styrylpyridine–Tetracyanobenzene Cocrystals
Authors: Sun Lingjie , Zhu Weigang , Wang Wei , Yang Fangxu , Zhang Congcong , Wang Shufeng , Zhang Xiaotao , Li Rongjin , Dong Huanli , Hu Wenping
Published: May 2017

Cocrystals of 4‐styrylpyridine and 1,2,4,5‐tetracyanobenzene were successfully prepared by supramolecular self‐assembly. Donor–acceptor interactions between the molecular components are the main driving force for self‐assembly and contribute to intermolecular charge transfer. The cocrystals possess two‐photon absorption properties that are not observed in the individual components; suggesting that two‐photon absorption originates from intermolecular charge‐transfer interactions in the donor–acceptor system. The origin of two‐photon absorption in multichromophore systems remains under‐researched; thus, the system offers a rare demonstration of two‐photon absorption by cocrystallization. Cocrystal engineering may facilitate further design and development of novel materials for nonlinear optical and optoelectronic applications.
Regioselective Synthesis of Polycyclic and Heptagon‐embedded Aromatic Compounds through a Versatile π‐Extension of Aryl Halides
Authors: Fu Wai Chung , Wang Zheng , Chan Wesley Ting Kwok , Lin Zhenyang , Kwong Fuk Yee
Published: May 2017

A versatile π‐extension reaction was developed based on the three‐component cross‐coupling of aryl halides, 2‐haloarylcarboxylic acids, and norbornadiene. The transformation is driven by the direction and subsequent decarboxylation of the carboxyl group, while norbornadiene serves as an ortho‐C−H activator and ethylene synthon via a retro‐Diels–Alder reaction. Comprehensive DFT calculations were performed to account for the catalytic intermediates.
Harnessing [1,4], [1,5], and [1,6] Anionic Fries‐type Rearrangements by Reaction‐Time Control in Flow
Authors: Kim Heejin , Inoue Keita , Yoshida Jun‐ichi
Published: May 2017

A series of anionic Fries‐type rearrangements of carbamoyl‐substituted aryllithium intermediates were controlled by using flow microreactor systems. For the [1,4] and [1,5] rearrangements, the aryllithium intermediate formed before carbamoyl migration and the lithium alkoxide formed after carbamoyl migration can be selectively subjected to subsequent reactions with electrophiles by precisely controlling the residence time and temperature (−25 to −50 °C). In contrast, the [1,6] rearrangement is rather slow even at −25 °C. The absence of crossover products indicates the intramolecular nature of the carbamoyl group migration.
Divergent Synthesis of Disulfanes and Benzenesulfonothioates Bearing 2‐Aminofurans From N‐Tosylhydrazone‐Bearing Thiocarbamates
Authors: Mai Shaoyu , Song Qiuling
Published: May 2017

An efficient and convenient synthesis of valuable disulfanes and benzenesulfonothioates, having a 2‐aminofuran framework, has been developed by employing a copper‐catalyzed transformation of readily available N‐tosylhydrazone‐bearing thiocarbamates. This method features an inexpensive metal catalyst, mild reaction conditions, good functional‐group tolerance, short reaction times, and delivers valuable and complex products. A copper carbene generated from an N‐tosylhydrazone‐bearing thiocarbamate is proposed as the key intermediate for the transformation and it triggers the subsequent cascade. Remarkably, the Ts anion released from N‐tosylhydrazone further serves as a nucleophile, thus rendering the formation of benzenesulfonothioates under controlled conditions.
A Schiff base‐grafted nanoporous silica material as a reversible optical probe for Hg2+ ion in water
Authors: Afshani Jafar , Badiei Alireza , Karimi Mehdi , Lashgari Negar , Mohammadi Ziarani Ghodsi
Published: May 2017

A novel organic–inorganic silica‐based fluorescent probe was designed, synthesized and characterized by different techniques such as XRD, BET, TGA, and FT‐IR. The fluorescence properties of the probe were studied in the presence of a variety of metal‐ions in water. The results revealed that various metal‐ions negligibly vary the emission intensity of the probe except for Hg2+, which quenched the intensity dramatically. The selectivity of the probe toward Hg2+ ion was further investigated in the presence of common competing metal‐ions and the results demonstrated the high selectivity of the probe toward Hg2+ ion. The fluorescence emission of the probe was also studied as a function of the concentration of Hg2+ ion. A nanomolar limit of detection was estimated for Hg2+, indicating a high sensitivity. Furthermore, the probe showed INHIBIT‐type logic behavior with Hg2+ and H+ as inputs. Also, the optimum pH range was studied in addition to reversibility and real world applicability of the probe.
Facile synthesis of indene and fluorene derivatives through AlCl3‐catalyzed cyclization of in situ formed iminium ions
Authors: Chen Lei , Teng Wei , Geng Xin‐Le , Zhu Yi‐Fan , Guan Yong‐Hong , Fan Xiaohui
Published: May 2017

A simple AlCl3‐catalyzed condensation/cyclization cascade process between aldehydes and sulfonamide is reported, in which two new bonds and one five‐membered ring are simultaneously formed with water as the byproduct. This method provides a rapid access to indenamine and 9‐aminofluorene derivatives. Additionally, these products can be transformed into corresponding indanones and fluorenones under the developed conditions.
Terbium–organic framework as heterogeneous Lewis acid catalyst for β‐aminoalcohol synthesis: Efficient, reusable and green catalytic method
Authors: Karimi Meghdad , Hajiashrafi Taraneh , Heydari Akbar , Azhdari Tehrani Alireza
Published: May 2017

A terbium–organic framework (Tb‐MOF) was prepared using a previously reported procedure. Tb‐MOF was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, powder X‐ray diffraction and surface area analysis. Tb‐MOF was employed as a heterogeneous Lewis acid catalyst for the synthesis of β‐aminoalcohols. Also, the effect of ultrasonic irradiation was examined in the catalytic aminolysis of styrene oxide. The reaction conditions were optimized by variation of reaction time, catalyst concentration and solvent. A variety of β‐aminoalcohols were synthesized and characterized. The Tb‐MOF catalyst showed excellent selectivity and high yield for these transformations.
Graphene Oxide Conjugated Magnetic Beads for RNA Extraction
Authors: Pham Xuan‐Hung , Baek Ahruem , Kim Tae Han , Lee Sang Hun , Rho Won‐Yeop , Chung Woo‐Jae , Kim Dong‐Eun , Jun Bong‐Hyun
Published: May 2017

A magnetic material that consists of silica‐coated magnetic beads conjugated with graphene oxide (GO) was successfully prepared for facile ribonucleic acid (RNA) extraction. When the GO‐modified magnetic beads were applied to separate the RNA from the lysed cell, the cellular RNAs were readily adsorbed to and readily desorbed from the surface of the GO‐modified magnetic beads by urea. The amount of RNA extracted by the GO‐modified magnetic beads was ≈170 % as much as those of the control extracted by a conventional phenol‐based chaotropic solution. These results demonstrate that the facile method of RNA separation by using GO‐modified magnetic beads as an adsorbent is an efficient and simple way to purify intact cellular RNAs and/or microRNA from cell lysates.
Observer Design for a Time Delay System via the Razumikhin Approach
Authors: Rehák Branislav
Published: May 2017

The paper presents an algorithm for the observer design for linear systems with time delay. The observer design is based on a solution of a set of linear matrix inequalities. They are derived using the Razumikhin functional. Quantization effects on the observation error are also studied, a bound on the observation error caused by quantization is derived. Two illustrative examples are presented.
Feedback between surface air temperature and atmospheric circulation in high‐temperature weather in East China: a diurnal perspective
Authors: Zeng X.‐M. , Zuo C. , Zhang Y. , Wang N. , Zheng Y. , Chen C.
Published: May 2017

This study proposes the generality of surface air temperature (SAT)–atmospheric circulation feedback during high‐temperature weather in late July 2003 over East China by using the Advanced Research Weather Research and Forecasting model (WRF; Version 3) simulations with a succession of 24‐h integrations, i.e. on a daily scale, the SAT increase leads to a weakened ridge of the western Pacific subtropical high in the lower troposphere (i.e. negative feedback), whereas it leads to a strengthened ridge in the upper troposphere (i.e. positive feedback) and vice versa. Additionally, using the balance equation of temperature, the feedbacks are clarified from the diurnal‐variation perspective. This shows many complex details, e.g. the changes in geopotential heights are more complex than those in air temperatures, and the overall daily feedback appears to be dominated by the feedback during the phase with intense daytime surface heating. All of the WRF‐modified land surface conditions can lead to large changes in the maximum, minimum, and average SATs over the mean diurnal scale, with generally larger differences induced by land surface schemes than those induced by initial soil moisture, suggesting that the SAT–circulation feedback can be greatly reduced (or amplified) by different land conditions over the diurnal weather scale and that diurnal variations could substantially contribute to longer timescale climate.