bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extreme Carbon Dioxide Sorption Hysteresis in Open‐Channel Rigid Metal–Organic Frameworks
Authors: Bezuidenhout Charl X. , Smith Vincent J. , Bhatt Prashant M. , Esterhuysen Catharine , Barbour Leonard J. 
Published: January 2015

AbstractA systematic study is presented of three closely related microporous metal‐organic frameworks the pore dimensions of which vary according to the choice of 4,4′‐bipyridyl linker. The tunable linker allows exploration of the effect of increasing pore dimensions on the sorption behavior of the frameworks. The MOFs described capture CO2 under supercritical conditions and continue to sequester the gas under ambient conditions. Gas sorption isotherms for CO2 are compared with thermogravimetric data, and the CO2 molecules in the channels of the frameworks could be modeled using single‐crystal X‐ray diffraction analysis. Crystallographic data were used to construct a theoretical model based on DFT methods to calculate framework electrostatic potential maps with a view to understanding the nature of the sorbate–sorbent interactions.
A Nanoparticle Catalyst for Heterogeneous Phase Para‐Hydrogen‐Induced Polarization in Water
Authors: Glöggler Stefan , Grunfeld Alexander M. , Ertas Yavuz N. , McCormick Jeffrey , Wagner Shawn , Schleker P. Philipp M. , Bouchard Louis‐S. 
Published: January 2015

AbstractPara‐hydrogen‐induced polarization (PHIP) is a technique capable of producing spin polarization at a magnitude far greater than state‐of‐the‐art magnets. A significant application of PHIP is to generate contrast agents for biomedical imaging. Clinically viable and effective contrast agents not only require high levels of polarization but heterogeneous catalysts that can be used in water to eliminate the toxicity impact. Herein, we demonstrate the use of Pt nanoparticles capped with glutathione to induce heterogeneous PHIP in water. The ligand‐inhibited surface diffusion on the nanoparticles resulted in a 1H polarization of P=0.25 % for hydroxyethyl propionate, a known contrast agent for magnetic resonance angiography. Transferring the 1H polarization to a 13C nucleus using a para‐hydrogen polarizer yielded a polarization of 0.013 %. The nuclear‐spin polarizations achieved in these experiments are the first reported to date involving heterogeneous reactions in water.
Enhanced Electron Penetration through an Ultrathin Graphene Layer for Highly Efficient Catalysis of the Hydrogen Evolution Reaction
Authors: Deng Jiao , Ren Pengju , Deng Dehui , Bao Xinhe 
Published: January 2015

AbstractMajor challenges encountered when trying to replace precious‐metal‐based electrocatalysts of the hydrogen evolution reaction (HER) in acidic media are related to the low efficiency and stability of non‐precious‐metal compounds. Therefore, new concepts and strategies have to be devised to develop electrocatalysts that are based on earth‐abundant materials. Herein, we report a hierarchical architecture that consists of ultrathin graphene shells (only 1–3 layers) that encapsulate a uniform CoNi nanoalloy to enhance its HER performance in acidic media. The optimized catalyst exhibits high stability and activity with an onset overpotential of almost zero versus the reversible hydrogen electrode (RHE) and an overpotential of only 142 mV at 10 mA cm−2, which is quite close to that of commercial 40 % Pt/C catalysts. Density functional theory (DFT) calculations indicate that the ultrathin graphene shells strongly promote electron penetration from the CoNi nanoalloy to the graphene surface. With nitrogen dopants, they synergistically increase the electron density on the graphene surface, which results in superior HER activity on the graphene shells.
Direct Asymmetric Dearomatization of 2‐Naphthols by Scandium‐Catalyzed Electrophilic Amination
Authors: Nan Jiang , Liu Jingjing , Zheng Huayu , Zuo Zhijun , Hou Lei , Hu Huaiming , Wang Yaoyu , Luan Xinjun 
Published: January 2015

AbstractCatalytic asymmetric aminative dearomatization of 1‐substituted 2‐naphthols was successfully implemented with electrophilic azodicarboxylates under the catalysis of chiral ScIII/pybox complexes. This intermolecular reaction represents a hitherto unknown enantioselective CN bond‐forming process through direct dearomatization of phenolic compounds to generate chiral nitrogen‐containing quaternary carbon stereocenters.
Vielseitige Farbstoffsynthesen durch mehrfache Kondensationsreaktionen von Acetylanilinen mit Perylenanhydriden
Authors: Jänsch Daniel , Li Chen , Chen Long , Wagner Manfred , Müllen Klaus 
Published: January 2015

AbstractMit der Transformation von Rylenen zu neuen Chromophorfamilien wird ein weiterer Schlüsselschritt der Rylenchemie vorgestellt. Die Imidierung von Rylenanhydriden mit 2‐Acetylanilinen kann durch die Wahl des Lösungsmittels dahingehend gesteuert werden, dass eine Umsetzung entweder zu einer 4‐Hydroxychinolin‐ (4‐HQ) oder einer 4‐Oxochinolineinheit (4‐OQ) erfolgt. Das 4‐HQ‐Motiv enthält eine Aminoenongruppe, die durch eine intramolekulare Aldolkondensation gebildet wird und damit das erste vinyloge Rylenimid darstellt. Das Konzept der Vinylogisierung wird durch die Verwendung von 2,6‐Diacetylanilin weiter entwickelt, wodurch ein 3a‐Aza‐1,6‐phenalendion‐erweitertes Rylengerüst mit vollständig eingebettetem Stickstoffatom erhalten wird. Durch Funktionalisierung der Aminoenonfunktionen, z. B. durch Malonsäuredinitriladdition, können die optischen und elektronischen Eigenschaften weiter modifiziert werden.
Simplified Electrochemically Mediated Atom Transfer Radical Polymerization using a Sacrificial Anode
Authors: Park Sangwoo , Chmielarz Paweł , Gennaro Armando , Matyjaszewski Krzysztof 
Published: January 2015

AbstractSimplification of electrochemically mediated atom transfer radical polymerization was achieved efficiently under either potentiostatic or galvanostatic conditions using an aluminum wire sacrificial anode (seATRP) immersed directly into the reaction flask without separating the counter electrode. seATRP polymerizations were carried out under different applied potentials, Eapps=E1/2, Epc, Epc −40 mV, and Epc −80 mV. As the rate of polymerization (Rp) can be modulated by applying different Eapp potentials, more reducing conditions resulted in faster Rp. The polymerization results showed similar narrow molecular‐weight distribution throughout the reactions, similar to results observed for n‐butyl acrylate (BA) polymerization under conventional eATRP. High‐molecular‐weight PBA and diblock copolymers were synthesized by seATRP with more than 90 % monomer conversion. Furthermore, galvanostatic conditions were developed for synthesizing PBA with the two‐electrode system.
Isolation of a Hydrogen‐Bonded Complex Based on the Anthranol/Anthroxyl Pair: Formation of a Hydrogen‐Atom Self‐Exchange System
Authors: Hirao Yasukazu , Saito Tohru , Kurata Hiroyuki , Kubo Takashi 
Published: January 2015

AbstractA hydrogen‐bonded complex was successfully isolated as crystals from the anthranol/anthroxyl pair in the self‐exchange proton‐coupled electron transfer (PCET) reaction. The anthroxyl radical was stabilized by the introduction of a 9‐anthryl group at the carbon atom at the 10‐position. The hydrogen‐bonded complex with anthranol self‐assembled by π–π stacking to form a one‐dimensional chain in the crystal. The conformation around the hydrogen bond was similar to that of the theoretically predicted PCET activated complex of the phenol/phenoxyl pair. X‐ray crystal analyses revealed the self‐exchange of a hydrogen atom via the hydrogen bond, indicating the activation of the self‐exchange PCET reaction between anthranol and anthroxyl. Magnetic measurements revealed that magnetic ordering inside the one‐dimensional chain caused the inactivation of the self‐exchange reaction.
The Nature of Photocatalytic “Water Splitting” on Silicon Nanowires
Authors: Liu Dong , Li Leilei , Gao Yang , Wang Chengming , Jiang Jun , Xiong Yujie 
Published: January 2015

AbstractSilicon should be an ideal semiconductor material if it can be proven usable for photocatalytic water splitting, given its high natural abundance. Thus it is imperative to explore the possibility of water splitting by running photocatalysis on a silicon surface and to decode the mechanism behind it. It is reported that hydrogen gas can indeed be produced from Si nanowires when illuminated in water, but the reactions are not a real water‐splitting process. Instead, the production of hydrogen gas on the Si nanowires occurs through the cleavage of SiH bonds and the formation of SiOH bonds, resulting in the low probability of generating oxygen. On the other hand, these two types of surface dangling bonds both extract photoexcited electrons, whose competition greatly impacts on carrier lifetime and reaction efficiency. Thus surface chemistry holds the key to achieving high efficiency in such a photocatalytic system.
Atomically Thin Arsenene and Antimonene: Semimetal–Semiconductor and Indirect–Direct Band‐Gap Transitions
Authors: Zhang Shengli , Yan Zhong , Li Yafei , Chen Zhongfang , Zeng Haibo 
Published: January 2015

AbstractThe typical two‐dimensional (2D) semiconductors MoS2, MoSe2, WS2, WSe2 and black phosphorus have garnered tremendous interest for their unique electronic, optical, and chemical properties. However, all 2D semiconductors reported thus far feature band gaps that are smaller than 2.0 eV, which has greatly restricted their applications, especially in optoelectronic devices with photoresponse in the blue and UV range. Novel 2D mono‐elemental semiconductors, namely monolayered arsenene and antimonene, with wide band gaps and high stability were now developed based on first‐principles calculations. Interestingly, although As and Sb are typically semimetals in the bulk, they are transformed into indirect semiconductors with band gaps of 2.49 and 2.28 eV when thinned to one atomic layer. Significantly, under small biaxial strain, these materials were transformed from indirect into direct band‐gap semiconductors. Such dramatic changes in the electronic structure could pave the way for transistors with high on/off ratios, optoelectronic devices working under blue or UV light, and mechanical sensors based on new 2D crystals.
Nitrosopurines En Route to Potently Cytotoxic Asmarines
Authors: Wan Kanny K. , Iwasaki Kotaro , Umotoy Jeffrey C. , Wolan Dennis W. , Shenvi Ryan A. 
Published: January 2015

AbstractA nitrosopurine ene reaction easily assembles the asmarine pharmacophore and transmits remote stereochemistry to the diazepine‐purine hetereocycle. This reaction generates potent cytotoxins which exceed the potency of asmarine A (1.2 μM IC50) and supersede the metabolites as useful leads for biological discovery.
Copper as a Robust and Transparent Electrocatalyst for Water Oxidation
Authors: Du Jialei , Chen Zuofeng , Ye Shengrong , Wiley Benjamin J. , Meyer Thomas J. 
Published: January 2015

AbstractCopper metal is in theory a viable oxidative electrocatalyst based on surface oxidation to CuIII and/or CuIV, but its use in water oxidation has been impeded by anodic corrosion. The in situ formation of an efficient interfacial oxygen‐evolving Cu catalyst from CuII in concentrated carbonate solutions is presented. The catalyst necessitates use of dissolved CuII and accesses the higher oxidation states prior to decompostion to form an active surface film, which is limited by solution conditions. This observation and restriction led to the exploration of ways to use surface‐protected Cu metal as a robust electrocatalyst for water oxidation. Formation of a compact film of CuO on Cu surface prevents anodic corrosion and results in sustained catalytic water oxidation. The Cu/CuO surface stabilization was also applied to Cu nanowire films, which are transparent and flexible electrocatalysts for water oxidation and are an attractive alternative to ITO‐supported catalysts for photoelectrochemical applications.
Structural Characterization of O‐ and C‐Glycosylating Variants of the Landomycin Glycosyltransferase LanGT2
Authors: Tam Heng Keat , Härle Johannes , Gerhardt Stefan , Rohr Jürgen , Wang Guojun , Thorson Jon S. , Bigot Aurélien , Lutterbeck Monika , Seiche Wolfgang , Breit Bernhard , Bechthold Andreas , Einsle Oliver 
Published: January 2015

AbstractThe structures of the O‐glycosyltransferase LanGT2 and the engineered, CC bond‐forming variant LanGT2S8Ac show how the replacement of a single loop can change the functionality of the enzyme. Crystal structures of the enzymes in complex with a nonhydrolyzable nucleotide‐sugar analogue revealed that there is a conformational transition to create the binding sites for the aglycon substrate. This induced‐fit transition was explored by molecular docking experiments with various aglycon substrates.
Rhodium‐Catalyzed (5+1) Annulations Between 2‐Alkenylphenols and Allenes: A Practical Entry to 2,2‐Disubstituted 2H‐Chromenes
Authors: Casanova Noelia , Seoane Andrés , Mascareñas José L. , Gulías Moisés 
Published: January 2015

AbstractReadily available alkenylphenols react with allenes under rhodium catalysis to provide valuable 2,2‐disubstituted 2H‐chromenes. The whole process, which involves the cleavage of one CH bond of the alkenyl moiety and the participation of the allene as a one‐carbon cycloaddition partner, can be considered a simple, versatile, and atom‐economical (5+1) heteroannulation. The reaction tolerates a broad range of substituents both in the alkenylphenol and in the allene, and most probably proceeds through a mechanism involving a rhodium‐catalyzed CC coupling followed by two sequential pericyclic processes.
Visible‐Light‐Driven CO2 Reduction with Carbon Nitride: Enhancing the Activity of Ruthenium Catalysts
Authors: Kuriki Ryo , Sekizawa Keita , Ishitani Osamu , Maeda Kazuhiko 
Published: January 2015

AbstractA heterogeneous photocatalyst system that consists of a ruthenium complex and carbon nitride (C3N4), which act as the catalytic and light‐harvesting units, respectively, was developed for the reduction of CO2 into formic acid. Promoting the injection of electrons from C3N4 into the ruthenium unit as well as strengthening the electronic interactions between the two units enhanced its activity. The use of a suitable solvent further improved the performance, resulting in a turnover number of greater than 1000 and an apparent quantum yield of 5.7 % at 400 nm. These are the best values that have been reported for heterogeneous photocatalysts for CO2 reduction under visible‐light irradiation to date.
Structural aspects of mechanical properties of iPP‐based composites. I. Composite iPP fibers with VGCF nanofiller
Authors: Ivan'kova Elena , Kasatkin Igor , Moskalyuk Olga , Yudin Vladimir , Kenny Jose Maria 
Published: January 2015

ABSTRACTNanocomposite fibers consisting of isotactic polypropylene (iPP) as a matrix filled with vapor grown carbon nanofibers (VGCF) have been prepared and their fine crystalline structure and mechanical properties characterized. The obtained results point out that the VGCF oriented along the fiber extrusion direction induce crystallization in the surrounding iPP matrix in a special way leading to the formation of oriented iPP α‐transcrystallite layers. The VGCF content and the draw ratio (DR) affect the textural properties of the composite material and lead to the formation of an anisotropic structure. The improvements of the mechanical properties of the composite fibers in both undrawn and drawn states are attributed to the VGCF aligning effect during extrusion, which produces highly oriented iPP crystalline structure, rather than to the reinforcing effect of the nanofibers. A new detailed scheme explaining the changes in tensile strength from the structural point of view is proposed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41865.
Study on poly(butylene adipate‐co‐terephthalate)/starch composites with polymeric methylenediphenyl diisocyanate
Authors: Kim Ji‐Hoo , Lee Jae Choon , Kim Gue‐Hyun 
Published: January 2015

ABSTRACTTo lower the cost of poly(butylene adipate‐co‐terephthalate) or PBAT, starch was used as a filler in this study. To increase tensile strength of PBAT/starch composites, polymeric methylenediphenyl diisocyanate (pMDI) was used as a compatibilizer. PBAT was melt‐mixed with starch in a kneader, and then the mixtures were compression‐molded. The effects of starch and pMDI content on the tensile strength and elongation at break of PBAT/starch composites were examined. The morphology and biodegradability of the composites in soil were also studied. The tensile strength of PBAT and PBAT/starch composites increases with increasing content of pMDI. The increase of weight average molecular weight of PBAT and improved interaction between PBAT and starch were observed with increasing content of pMDI. The weight average molecular weights of buried PBAT and the composites in soil significantly decrease. Especially, the reduction of the weight average molecular weight of PBAT/starch (70/30) composite is the most significant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41884.
Brief Report: Successful In Vitro Culture of Rheumatoid Arthritis Synovial Tissue Explants at the Air–Liquid Interface
Authors: Sakuraba Koji , Fujimura Kenjiro , Nakashima Yasuharu , Okazaki Ken , Fukushi Jun‐ichi , Ohishi Masanobu , Oyamada Akiko , Esaki Yukio , Miyahara Hisaaki , Iwamoto Yukihide , Yoshikai Yasunobu , Yamada Hisakata 
Published: January 2015

ObjectiveTo establish a method to culture synovial tissue explants from patients with rheumatoid arthritis (RA).MethodsSynovial tissue explants obtained from 10 patients with RA were cultured at the air–liquid interface or were submerged in culture medium. As a control, synovial explants were engrafted subcutaneously into SCID mice. The synovial explants were harvested at different time points, and histologic or flow cytometric analysis was performed. Cytokine levels in the culture supernatants were measured by enzyme‐linked immunosorbent assay. Infliximab was added to the air–liquid interface culture to evaluate the effect of tumor necrosis factor α blockade on inflammatory cytokine production.ResultsThe histologic features of RA synovitis, including a hyperplastic lining layer and the presence of cellular infiltrate in the sublining layer, were maintained in synovial tissue explants in air–liquid interface culture. In synovial grafts harvested from SCID‐HuRAg mice, the cellular infiltrate was well maintained in the sublining, but the lining layer was lost. Viable CD4+ T cells and macrophages were abundant after air–liquid interface culture but were virtually absent after submerged culture. Furthermore, synovial tissue explants in air–liquid interface culture produced interleukin‐6 (IL‐6) and IL‐8 for a prolonged period of time. The addition of infliximab effectively reduced cytokine production.ConclusionRA synovial explants can be maintained for weeks using an air–liquid interface culture. This simple culture system might be useful for analyzing the pathogenesis of RA synovitis and for developing antirheumatic drugs.
An Electrochemical Strategy to Measure the Thickness of Electroactive Microbial Biofilms
Authors: Millo Diego 
Published: January 2015

AbstractThe study of electroactive microbial biofilms often requires knowledge of the biofilm thickness. Unfortunately, this parameter is, nowadays, only accessible through expensive microscopic techniques. This work overcomes this limitation by presenting a new strategy, exploiting the use of chronoamperometry (CA) alone. A mixed‐culture biofilm is exposed to an O2‐saturated solution during anode respiration to suppress its catalytic activity. Assuming that inactivation of the electrocatalytic process is caused by O2 diffusion through the biofilm, a simple relation allows the use of the time constant extracted from the fitting of the curve of the CA trace during inactivation for the straightforward and quantitative determination of biofilm thickness. The biofilm thickness obtained with this method obeys the expected trend reported for biofilm growth and is in agreement with optical measurements. Contrary to the techniques usually employed to determine biofilm thickness, this new strategy is very rapid, nondisruptive, inexpensive, and may become a convenient alternative with respect to expensive and time‐consuming microscopic techniques.
Modular Synthesis of Linear Bis‐ and Tris‐monodentate Fused [6]Polynorbornane‐Based Ligands and their Assembly into Coordination Cages
Authors: Johnstone Mark D. , Schwarze Eike K. , Clever Guido H. , Pfeffer Frederick M. 
Published: January 2015

AbstractA modular approach has been developed for the synthesis of rigid linear di‐ and tritopic ligands based on a fused [6]polynorbornane scaffold. The design provides up to three sites for installing functionality, including both “ends” and a “central” position with the advantage that each region can be independently addressed during synthesis. To illustrate the utility of the approach, both pyridyl and picolyl units were incorporated to provide six new ligands, with centers and ends either matched or mismatched. Indeed, both [M2L4] cages with endohedral functionality and [M3L4] complexes were cleanly produced from these ligands with assembled structures confirmed by using 1H NMR spectroscopy, HRMS, and molecular modelling.
Extending the Substrate Scope of Bicyclic P‐Oxazoline/Thiazole Ligands for Ir‐Catalyzed Hydrogenation of Unfunctionalized Olefins by Introducing a Biaryl Phosphoroamidite Group
Authors: Biosca Maria , Paptchikhine Alexander , Pàmies Oscar , Andersson Pher G. , Diéguez Montserrat 
Published: January 2015

AbstractThis study identifies a series of Ir‐bicyclic phosphoroamidite–oxazoline/thiazole catalytic systems that can hydrogenate a wide range of minimally functionalized olefins (including E‐ and Z‐tri‐ and disubstituted substrates, vinylsilanes, enol phosphinates, tri‐ and disubstituted alkenylboronic esters, and α,β‐unsaturated enones) in high enantioselectivities (ee values up to 99 %) and conversions. The design of the new phosphoroamidite–oxazoline/thiazole ligands derives from a previous successful generation of bicyclic N‐phosphane–oxazoline/thiazole ligands, by replacing the N‐phosphane group with a π‐acceptor biaryl phosphoroamidite moiety. A small but structurally important family of Ir‐phosphoroamidite–oxazoline/thiazole precatalysts has thus been synthesized by changing the nature of the N‐donor group (either oxazoline or thiazole) and the configuration at the biaryl phosphoroamidite moiety. The substitution of the N‐phosphane by a phosphoroamidite group in the bicyclic N‐phosphane–oxazoline/thiazole ligands extended the range of olefins that can be successfully hydrogenated.
On Copper(I) Fluorides, the Cuprophilic Interaction, the Preparation of Copper Nitride at Room Temperature, and the Formation Mechanism at Elevated Temperatures
Authors: Woidy Patrick , Karttunen Antti J. , Widenmeyer Marc , Niewa Rainer , Kraus Florian 
Published: January 2015

AbstractOur attempts to synthesize the hitherto unknown binary copper(I) fluoride have led to first successes and a serendipitious result: By conproportionation of elemental copper and copper(II) fluoride in anhydrous liquid ammonia, two copper(I) fluorides were obtained as simple NH3 complexes. One of them presents an example of ligand‐unsupported “cuprophilic” interactions in an infinite [Cu2(NH3)4]2+ chain with alternating Cu–Cu distances. We discovered that both copper(I) fluorides can easily be converted into Cu3N at room temperature, just by applying a vacuum. Additionally, we investigated the formation mechanism of the classical synthesis route of Cu3N that starts with CuF2 and flowing NH3 in the temperature range between ambient and 290 °C by means of thermal analysis and in situ neutron diffraction. The reaction proceeds at elevated temperatures through the formation of a blue and amorphous ammoniate Cu(NH3)2F2, the reformation of CuF2, and finally the redox reaction to form Cu3N.