bluuebunny/crossref_metadata_2025_split huggingface dataset:
Palladium–Borane Cooperation: Evidence for an Anionic Pathway and Its Application to Catalytic Hydro‐/Deutero‐dechlorination
Authors: Kameo Hajime , Yamamoto Jun , Asada Ayaka , Nakazawa Hiroshi , Matsuzaka Hiroyuki , Bourissou Didier 
Published: October 2019

AbstractMetal–Lewis acid cooperation provides new opportunities in catalysis. In this work, we report a new type of palladium–borane cooperation involving anionic Pd0 species. The air‐stable DPB palladium complex 1 (DPB=diphosphine‐borane) was prepared and reacted with KH to give the Pd0 borohydride 2, the first monomeric anionic Pd0 species to be structurally characterized. The boron moiety acts as an acceptor towards Pd in 1 via Pd→B interaction, but as a donor in 2 thanks to B‐H‐Pd bridging. This enables the activation of C−Cl bonds and the system is amenable to catalysis, as demonstrated by the hydro‐/deutero‐dehalogenation of a variety of (hetero)aryl chlorides (20 examples, average yield 85 %).
Cu‐Mediated Amination of (Hetero)Aryl C−H bonds with NH Azaheterocycles
Authors: Yu Jin‐Feng , Li Jian‐Jun , Wang Peng , Yu Jin‐Quan 
Published: October 2019

AbstractDirect synthesis of N‐(hetero)arylated heteroarenes has been realized through Cu‐mediated C−N coupling of NH azaheterocycles with aryl C−H bonds under aerobic conditions. This method features a broad scope of both heterocyclic arenes (pyridine, quinoline, pyrazole, imidazole, furan, thiophene, benzofuran, and indole) and NH azaheterocycles (imidazole, pyrazole, indole, azindole, purine, indazole, benzimidazole, pyridone, carbazole), providing a versatile method for the synthesis of pharmaceutically important N‐(hetero)arylated heteroarenes. The versatility of this reaction was further demonstrated through late‐stage modification of marketed drugs and the synthesis of a key intermediate for accessing a class of angiotensin II receptor 1 antagonists.
Engineered C–N Lyase: Enantioselective Synthesis of Chiral Synthons for Artificial Dipeptide Sweeteners
Authors: Zhang Jielin , Grandi Eleonora , Fu Haigen , Saravanan Thangavelu , Bothof Laura , Tepper Pieter G. , Thunnissen Andy‐Mark W. H. , Poelarends Gerrit J. 
Published: October 2019

AbstractAspartic acid derivatives with branched N‐alkyl or N‐arylalkyl substituents are valuable precursors to artificial dipeptide sweeteners such as neotame and advantame. The development of a biocatalyst to synthesize these compounds in a single asymmetric step is an as yet unmet challenge. Reported here is an enantioselective biocatalytic synthesis of various difficult N‐substituted aspartic acids, including N‐(3,3‐dimethylbutyl)‐l‐aspartic acid and N‐[3‐(3‐hydroxy‐4‐methoxyphenyl)propyl]‐l‐aspartic acid, precursors to neotame and advantame, respectively, using an engineered variant of ethylenediamine‐N,N′‐disuccinic acid (EDDS) lyase from Chelativorans sp. BNC1. This engineered C–N lyase (mutant D290M/Y320M) displayed a remarkable 1140‐fold increase in activity for the selective hydroamination of fumarate compared to that of the wild‐type enzyme. These results present new opportunities to develop practical multienzymatic processes for the more sustainable and step‐economic synthesis of an important class of food additives.
Bor in energiebezogenen Prozessen und Anwendungen
Authors: Huang Zhenguo , Wang Suning , Dewhurst Rian D. , Ignat'ev Nikolai V. , Finze Maik , Braunschweig Holger 
Published: October 2019

AbstractDirekt an der Grenze zwischen Metallen und Nichtmetallen angesiedelt, nimmt das Element Bor eine einzigartige Position im Periodensystem ein. Diese besondere Stellung ermöglicht eine enorme Vielfalt an chemischen Reaktionen und Anwendungen. Auch in Hinblick auf die stetig steigende Nachfrage an erneuerbaren und sauberen Energien bzw. energieeffizienten Prozessen ist das Element Bor mehr und mehr in den Fokus der energiebezogenen Forschung gerückt und umfasst mittlerweile Bereiche wie 1) die Aktivierung und Synthese kleiner energiereicher Moleküle, 2) die Speicherung von chemischer und elektrischer Energie und 3) die Umwandlung von elektrischer Energie zu Licht. Diese Anwendungen basieren hierbei auf den besonderen Eigenschaften des Elements Bor, d. h. vor allem auf dessen Elektronenmangel in Verbindung mit der Gegenwart eines unbesetzten p‐Orbitals, was die Ausbildung unzähliger Verbindungen mit gezielt beeinflussbaren chemischen und physikalischen Eigenschaften ermöglicht. So erreicht Bor beispielsweise mit vier kovalenten Bindungen und einer negativen Ladung relativ einfach ein Elektronenoktett, wodurch die Verbindungsklasse der Boratanionen zugänglich wird, welche eine außergewöhnlich hohe chemische und elektrochemische Stabilität aufweisen. Besonders hervorzuheben ist in diesem Zusammenhang die synthetisch wertvolle Klasse der schwach‐koordinierenden Anionen. Dieser Aufsatz soll die Bedeutung von Borverbindungen für energiebezogene Prozesse und Anwendungen verdeutlichen und fasst die Fortschritte der letzten Jahre auf diesem Gebiet zusammen.
A Novel Long‐Range n to π* Interaction Secures the Smallest known α‐Helix in Water
Authors: Hoang Huy N. , Wu Chongyang , Hill Timothy A. , Dantas de Araujo Aline , Bernhardt Paul V. , Liu Ligong , Fairlie David P. 
Published: October 2019

AbstractThe introduction of an amide bond linking side chains of the first and fifth amino acids forms a cyclic pentapeptide that optimally stabilizes the smallest known α‐helix in water. The origin of the stabilization is unclear. The observed dependence of α‐helicity on the solvent and cyclization linker led us to discover a novel long‐range n to π* interaction between a main‐chain amide oxygen and a uniquely positioned carbonyl group in the linker of cyclic pentapeptides. CD and NMR spectra, NMR and X‐ray structures, modelling, and MD simulations reveal that this first example of a synthetically incorporated long‐range n to π* CO⋅⋅⋅Cγ=Ο interaction uniquely enforces an almost perfect and remarkably stable peptide α‐helix in water but not in DMSO. This unusual interaction with a covalent amide bond outside the helical backbone suggests new approaches to synthetically stabilize peptide structures in water.
Phosphorylation Reduces the Mechanical Stability of the α‐Catenin/ β‐Catenin Complex
Authors: Le Shimin , Yu Miao , Yan Jie 
Published: October 2019

AbstractThe α‐catenin/β‐catenin complex serves as a critical molecular interface involved in cadherin–catenin‐based mechanosensing at the cell–cell adherence junction that plays a critical role in tissue integrity, repair, and embryonic development. This complex is subject to tensile forces due to internal actomyosin contractility and external mechanical micro‐environmental perturbation. However, the mechanical stability of this complex has yet to be quantified. Here, we directly quantified the mechanical stability of the α‐catenin/β‐catenin complex and showed that it has enough mechanical stability to survive for tens to hundreds of seconds within physiological level of forces up to 10 pN. Phosphorylation or phosphotyrosine‐mimetic mutations (Y142E or/and T120E) on β‐catenin shorten the mechanical lifetime of the complex by tens of fold over the same force range. These results provide insights into the regulation of the α‐catenin/β‐catenin complex by phosphorylation.
Molecular Engineering of a 3D Self‐Supported Electrode for Oxygen Electrocatalysis in Neutral Media
Authors: Xie Lisi , Li Xialiang , Wang Bin , Meng Jia , Lei Haitao , Zhang Wei , Cao Rui 
Published: October 2019

AbstractElectrodes for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are required in energy conversion and storage technologies. An assembly strategy involves covalently grafting Co corrole 1 onto Fe3O4 nanoarrays grown on Ti mesh. The resulted electrode shows significantly improved activity and durability for OER and ORR in neutral media as compared to Fe3O4 alone and with directly adsorbed 1. It also displays higher atom efficiency (at least two magnitudes larger turnover frequency) than reported electrodes. Using this electrode in a neutral Zn‐air battery, a small charge–discharge voltage gap of 1.19 V, large peak power density of 90.4 mW cm−2, and high rechargeable stability for >100 h are achieved, opening a promising avenue of molecular electrocatalysis in a metal–air battery. This work shows a molecule‐engineered electrode for electrocatalysis and demonstrates their potential applications in energy conversion and storage.
An Organic Crystal with High Elasticity at an Ultra‐Low Temperature (77 K) and Shapeability at High Temperatures
Authors: Liu Huapeng , Ye Kaiqi , Zhang Zuolun , Zhang Hongyu 
Published: October 2019

AbstractOrganic single crystals with elastic bending capability and potential applications in flexible devices and sensors have been elucidated. Exploring the temperature compatibility of elasticity is essential for defining application boundaries of elastic materials. However, related studies have rarely been reported for elastic organic crystals. Now, an organic crystal displays elasticity even in liquid nitrogen (77 K). The elasticity can be maintained below ca. 150 °C. At higher temperatures, the heat setting property enables us to make various shapes of crystalline fibers based on this single kind of crystal. Through detailed crystallographic analyses and contrast experiments, the mechanisms behind the unusual low‐temperature elasticity and high‐temperature heat setting are disclosed.
Bottom‐Up Assembly of DNA–Silica Nanocomposites into Micrometer‐Sized Hollow Spheres
Authors: Hu Yong , Grösche Maximilian , Sheshachala Sahana , Oelschlaeger Claude , Willenbacher Norbert , Rabe Kersten S. , Niemeyer Christof M. 
Published: October 2019

AbstractAlthough DNA nanotechnology has developed into a highly innovative and lively field of research at the interface between chemistry, materials science, and biotechnology, there is still a great need for methodological approaches for bridging the size regime of DNA nanostructures with that of micrometer‐ and millimeter‐sized units for practical applications. We report on novel hierarchically structured composite materials from silica nanoparticles and DNA polymers that can be obtained by self‐assembly through the clamped hybridization chain reaction. The nanocomposite materials can be assembled into thin layers within microfluidically generated water‐in‐oil droplets to produce mechanically stabilized hollow spheres with uniform size distributions at high throughput rates. The fact that cells can be encapsulated in these microcontainers suggests that our concept not only contributes to the further development of supramolecular bottom‐up manufacturing, but can also be exploited for applications in the life sciences.
Dynamic Open Coordination Cage from Nonsymmetrical Imidazole–Pyridine Ditopic Ligands for Turn‐On/Off Anion Binding
Authors: Ogata Daiji , Yuasa Junpei 
Published: October 2019

AbstractThis work demonstrates a new nonconventional ligand design, imidazole/pyridine‐based nonsymmetrical ditopic ligands (1 and 1S), to construct a dynamic open coordination cage from nonsymmetrical building blocks. Upon complex formation with Pd2+ at a 1:4 molar ratio, 1 and 1S initially form mononuclear PdL4 complexes (Pd2+(1)4 and Pd2+(1S)4) without formation of a cage. The PdL4 complexes undergo a stoichiometrically controlled structural transition to Pd2L4 open cages ((Pd2+)2(1)4 and (Pd2+)2(1S)4) capable of anion binding, leading to turn‐on anion binding. The structural transitions between the Pd2L4 open cage and the PdL4 complex are reversible. Thus, stoichiometric addition (2 equiv) of free 1S to the (Pd2+)2(1S)4 open cage holding a guest anion ((Pd2+)2(1S)4⋅G−) enables the structural transition to the Pd2+(1S)4 complex, which does not have a cage and thus causes the release of the guest anion (Pd2+(1S)4+G−).
Boron: Its Role in Energy‐Related Processes and Applications
Authors: Huang Zhenguo , Wang Suning , Dewhurst Rian D. , Ignat'ev Nikolai V. , Finze Maik , Braunschweig Holger 
Published: October 2019

AbstractBoron's unique position in the Periodic Table, that is, at the apex of the line separating metals and nonmetals, makes it highly versatile in chemical reactions and applications. Contemporary demand for renewable and clean energy as well as energy‐efficient products has seen boron playing key roles in energy‐related research, such as 1) activating and synthesizing energy‐rich small molecules, 2) storing chemical and electrical energy, and 3) converting electrical energy into light. These applications are fundamentally associated with boron's unique characteristics, such as its electron‐deficiency and the availability of an unoccupied p orbital, which allow the formation of a myriad of compounds with a wide range of chemical and physical properties. For example, boron's ability to achieve a full octet of electrons with four covalent bonds and a negative charge has led to the synthesis of a wide variety of borate anions of high chemical and electrochemical stability—in particular, weakly coordinating anions. This Review summarizes recent advances in the study of boron compounds for energy‐related processes and applications.
The Core Fucose on an IgG Antibody is an Endogenous Ligand of Dectin‐1
Authors: Manabe Yoshiyuki , Marchetti Roberta , Takakura Yohei , Nagasaki Masahiro , Nihei Wataru , Takebe Tomoyuki , Tanaka Katsunori , Kabayama Kazuya , Chiodo Fabrizio , Hanashima Shinya , Kamada Yoshihiro , Miyoshi Eiji , Dulal Hari Prasad , Yamaguchi Yoshiki , Adachi Yoshiyuki , Ohno Naohito , Tanaka Hiroshi , Silipo Alba , Fukase Koichi , Molinaro Antonio 
Published: October 2019

AbstractThe core fucose, a major modification of N‐glycans, is implicated in immune regulation, such as the attenuation of the antibody‐dependent cell‐mediated cytotoxicity of antibody drugs and the inhibition of anti‐tumor responses via the promotion of PD‐1 expression on T cells. Although the core fucose regulates many biological processes, no core fucose recognition molecule has been identified in mammals. Herein, we report that Dectin‐1, a known anti‐β‐glucan lectin, recognizes the core fucose on IgG antibodies. A combination of biophysical experiments further suggested that Dectin‐1 recognizes aromatic amino acids adjacent to the N‐terminal asparagine at the glycosylation site as well as the core fucose. Thus, Dectin‐1 appears to be the first lectin‐like molecule involved in the heterovalent and specific recognition of characteristic N‐glycans on antibodies.
Carbon radicals generated by solid polymers: Electron spin resonance spectroscopy for detection of species in water
Authors: Mochizuki Akira , Ono Dai , Kiminami Hideaki , Shinoda Sayaka , Abe Yoshihiko 
Published: October 2019

ABSTRACTRadicals generated in plastic medical devices (solid phase) by γ‐rays or electron‐beam irradiation during sterilization are known to cause oxidation of protein drugs, resulting in a loss or reduction in drug efficacy. The generation of radical species in water by the radical species in solid polymers has not been proved. Using electron spin resonance (ESR) spectroscopy, we confirm the generation of new radicals in water by γ‐ray irradiated cyclic olefin polymers (COP). ESR measurements are obtained using 4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPOL) as a spin probe and 5‐(2,2‐dimethyl‐1,3‐propoxycyclophosphoryl)‐5‐methyl‐1‐pyrroline N‐oxide (CYPMPO) as a spin trap, in which the irradiated COP was immersed. The ESR signals indicate the TEMPOL radicals decline over time, suggesting the generation of new radicals. Conversely, the characteristic ESR signals of the adduct formed by the reaction between CYPMPO and the hydroxyl radical are observed. Thus, hydroxyl radicals are generated because of the migration of the radicals from COP to water. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48604.
Rheology, morphological evolution, thermal, and mechanical properties of epoxy modified with polysulfone and cellulose nanofibers
Authors: Zhang Yan , Ling Qiuhui , Lu Xueting , Fang Qun , Sun Fangli 
Published: October 2019

ABSTRACTIn this work, the epoxy systems modified with polysulfone (PSF) and cellulose nanofiber (CNF) cured at different temperatures are prepared to investigate the effect of CNF on curing reaction, morphology evolution, rheology, thermal, and mechanical performance of composites. The reaction rate is increased and the activation energy is decreased with CNF incorporation, implying an accelerating effect of CNF on the epoxy‐amine reaction. The phase separation and gelation of the epoxy/PSF/CNF system start earlier compared with the binary system of epoxy/PSF. While it is displayed by rheology that both the system viscosity and relaxation time are elevated with CNF, presenting an inhibiting effect on phase evolution. Morphologies with smaller domain size are finally freezed by the epoxy gelation. The enhancement of impact performance for the epoxy/PSF/CNF composites is indicated by 40.2% increase in the impact strength, which is attributed to the finer phase‐separated morphology, the uniformly distributed CNF within the polymer matrix and the good load transfer between phases. In addition, the thermal stability of composites is improved as the CNFs existed in the phase‐separated polymer matrix can restrict the thermal motion of molecules during decomposition process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48628.
Larval development and proteolytic activity of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) exposed to different soybean protease inhibitors
Authors: Mendonça Eduardo G. , de Almeida Barros Rafael , Cordeiro Gláucia , da Silva Carolina R. , Campos Welligton G. , de Oliveira Joel A. , de Almeida Oliveira Maria G. 
Published: October 2019

AbstractAnticarsia gemmatalis represents a relevant factor for lowering soybean and other legume crop productivities. Protease inhibitors affect protein degradation and reduce the availability of amino acids, impairing the development and survival of insect pests. To evaluate the possible use of proteinaceous protease inhibitors in the management of this pest, the activities of midgut proteases and the growth and development of A. gemmatalis larvae exposed to soybean Bowman–Birk trypsin‐chymotrypsin inhibitor (SBBI) and soybean Kunitz trypsin inhibitor (SKTI) were determined. The survival curves obtained using Kaplan–Meier estimators indicated that SKTI and SBBI stimulated larval survival. However, the development of A. gemmatalis was delayed, and prepupal weight decreased in the presence of both inhibitors. The results showed that SKTI and SBBI inhibited the trypsin‐like and total proteolytic activities of larvae on the 12th day after eclosion. On the 15th day after eclosion, larvae exposed to SKTI increased the activities of trypsin and total proteases. Although SKTI and SBBI did not affect the survival of the insect, they had effects on midgut proteases in a stage wherein A. gemmatalis fed voraciously, increased the larval cycle, and decreased prepupal weight. These findings provide baseline information about the potential of proteinaceous protease inhibitors to manage the velvetbean caterpillar, avoiding chemical pesticides.
Identification and characterization of ethanol‐inducible promoters of Zymomonas mobilis based on omics data and dual reporter–gene system
Authors: Yang Yongfu , Rong Ziyue , Song Haoyue , Yang Xiuxiu , Li Mian , Yang Shihui 
Published: October 2019

AbstractZymomonas mobilis is a model bacterial ethanologen and has been engineered to produce lignocellulosic biofuels and biochemicals such as 2,3‐butanediol. We have previously identified promoters of different strengths using systems biology datasets and characterized them using the flow cytometry–based dual reporter–gene system. Here, we further demonstrated the capability of applying the dual reporter–gene system and omics datasets on discovering inducible promoters. Ten candidate ethanol‐inducible promoters were identified through omics datasets mining and clustering. Using the dual reporter–gene system, these promoters were characterized under natural growth, ethanol stress, and ethanol‐induced condition to investigate the transcriptional strength and ethanol inducibility. The results demonstrated that three promoters of P0405, P0435, and P0038 driving the expression of native genes of ZMO0405, ZMO0435, and ZMO0038, correspondingly, are potential ethanol‐responsive promoters and may be growth related. This study not only identified and verified three ethanol‐inducible promoters as biological parts, which can be used to synchronize the expression of heterologous pathway genes with the ethanol production process of Z. mobilis, but also demonstrated the power of combining omics datasets and dual reporter–gene system to identify biological parts for metabolic engineering and synthetic biology applications in Z. mobilis and related microorganisms.
Efficient production of gamma‐aminobutyric acid by engineered Saccharomyces cerevisiae with glutamate decarboxylases from Streptomyces
Authors: Yuan Haina , Zhang Wei , Xiao Gongnian , Zhan Jixun 
Published: October 2019

AbstractGamma‐aminobutyric acid (GABA) is an industrially valuable natural product. This study was aimed to establish an efficient food‐grade production process of GABA by engineering Saccharomyces cerevisiae that is generally recognized as safe (GRAS). GABA can be produced by catalytic decarboxylation of l‐glutamate (l‐Glu) by glutamate decarboxylase (GAD, EC4.1.1.15). Two GADs, SsGAD from Streptomyces sp. MJ654‐NF4 and ScGAD from Streptomyces chromofuscus ATCC 49982, were heterologously expressed in S. cerevisiae BJ5464. The engineered yeast strains were used as whole‐cell biocatalysts for GABA production. S. cerevisiae BJ5464/SsGAD exhibited significantly higher efficient catalytic activity than that of S. cerevisiae BJ5464/ScGAD. The optimal bioconversion system consisted of a cell density of OD600 30, 0.1 M l‐Glu, and 0.28 mM pyridoxal phosphate in 0.2 M Na2HPO4–citric acid buffer with pH 5.4, and the reactions were performed at 50 °C for 12 H. S. cerevisiae BJ5464/SsGAD cells can be reused, and the accumulated GABA titer reached 62.6 g/L after 10 batches with an overall molar conversion rate of 60.8 mol%. This work thus provides an effective production process of GABA using engineered yeast for food and pharmaceutical applications.
UV or blue light excited red persistent perovskite phosphor with millisecond lifetime for use in AC‐LEDs
Authors: Li Xiaoshuang , Zhao Lite 
Published: October 2019

AbstractEnergy storage phosphors with millisecond period afterglow that compensate for the diming time of alternating current light‐emitting diodes (AC‐LEDs) have promising application. To obtain a persistent luminescence (PersL) white colour in AC‐LEDs, we focussed on a red afterglow with short period phosphorescence. Ca4Ti3O10 forms a type of perovskite‐related Ruddlesden–Popper phase structure. Doping Pr3+ ions into Ca4Ti3O10, an ideal red PersL was obtained. X‐ray diffraction and element analysis demonstrated that our target samples were crystallized well. Steady‐state and afterglow luminescence properties were investigated in detail. Notably, the PersL intensity was dependent on various excitation wavelengths. By measuring three‐dimensional thermoluminescence spectra, we found that the trap depths showed a continuous distribution and that the shallowest trap contributed to the millisecond afterglow. Two PersL mechanism models were used to elucidate the electron charging and de‐trapping processes under UV or blue light activation.