bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Multi‐Component Sensor System for Detection of Amphiphilic Compounds
Authors: Xu Ming , Kelley Steven P. , Glass Timothy E. 
Published: August 2018

AbstractMany biologically important compounds are amphiphilic in character. Glycolipids, for example, represent a biologically important class of amphiphiles. Receptors and sensors for such compounds must also be amphiphilic making them a challenge to prepare. Here, a cucurbit[8]uril (CB[8])‐based sensor system has been prepared and tested for detection of amphiphilic compounds. This multi‐component system consists: a CB[8], which acts as a hydrophobic lipid receptor, a hydrophilic pyridinium‐based carbohydrate receptor, and a fluorescent indicator. The system self‐assembles in aqueous solution. The pyridinium quenches the fluorescence of the indicator giving a strong turn‐on response when it is displaced by the analyte. The sensor system was characterized by NMR, X‐ray crystallography, and fluorescence titrations.
A Unified Approach to Couple Aromatic Heteronucleophiles to Azines and Pharmaceuticals
Authors: Anderson Ryan G. , Jett Brianna M. , McNally Andrew 
Published: August 2018

AbstractCoupling aromatic heteronucleophiles to arenes is a common way to assemble drug‐like molecules. Many methods operate via nucleophiles intercepting organometallic intermediates, via Pd‐, Cu‐, and Ni‐catalysis, that facilitate carbon‐heteroatom bond formation and a variety of protocols. We present an alternative, unified strategy where phosphonium salts can replicate the behavior of organometallic intermediates. Under a narrow set of reaction conditions, a variety of aromatic heteronucleophile classes can be coupled to pyridines and diazines that are often problematic in metal‐catalyzed couplings, such as where (pseudo)halide precursors are unavailable in complex structures with multiple polar functional groups.
Two‐Color Valence‐to‐Core X‐ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase
Authors: Martinie Ryan J. , Blaesi Elizabeth J. , Bollinger J. Martin , Krebs Carsten , Finkelstein Kenneth D. , Pollock Christopher J. 
Published: August 2018

AbstractProton transfer reactions are of central importance to a wide variety of biochemical processes, though determining proton location and monitoring proton transfers in biological systems is often extremely challenging. Herein, we use two‐color valence‐to‐core X‐ray emission spectroscopy (VtC XES) to identify protonation events across three oxidation states of the O2‐activating, radical‐initiating manganese–iron heterodinuclear cofactor in a class I‐c ribonucleotide reductase. This is the first application of VtC XES to an enzyme intermediate and the first simultaneous measurement of two‐color VtC spectra. In contrast to more conventional methods of assessing protonation state, VtC XES is a more direct probe applicable to a wide range of metalloenzyme systems. These data, coupled to insight provided by DFT calculations, allow the inorganic cores of the MnIVFeIV and MnIVFeIII states of the enzyme to be assigned as MnIV(μ‐O)2FeIV and MnIV(μ‐O)(μ‐OH)FeIII, respectively.
Lowering Molecular Symmetry To Improve the Morphological Properties of the Hole‐Transport Layer for Stable Perovskite Solar Cells
Authors: Wang Xuchao , Zhang Jing , Yu Shuwen , Yu Wei , Fu Ping , Liu Xuan , Tu Dandan , Guo Xin , Li Can 
Published: August 2018

AbstractInspired by the structural feature of the classical hole‐transport material (HTM), Spiro‐OMeTAD, many analogues based on a highly symmetrical spiro‐core were reported for perovskite solar cells (PSCs). However, these HTMs were prone to crystallize because of the high molecular symmetry, forming non‐uniform films, unfavorable for the device stability and large‐area processing. By lowering the symmetry of spiro‐core, we report herein a novel spirobisindane‐based HTM, Spiro‐I, which could form amorphous films with high uniformity and morphological stability. Compared to the Spiro‐OMeTAD‐based PSCs, those containing Spiro‐I exhibit similar efficiencies for small area but higher ones for large area (1 cm2), and especially much higher air stability (retaining 80 % of initial PCE after 2400 h storage without encapsulation). Moreover, the Spiro‐I can be synthesized from a cheap starting material bisphenol A and used with a small amount for the device fabrication.
Scalable Wet Deposition of Zeolite AEI with a High Degree of Preferred Crystal Orientation
Authors: Huang Pei‐Sun , Lam Chon Hei , Su Chien‐You , Chen Yen‐Ru , Lee Wen‐Ya , Wang Da‐Ming , Hua Chi‐Chung , Kang Dun‐Yen 
Published: August 2018

AbstractProducing zeolite films with controlled preferred orientation on an industrial scale is a long‐standing challenge. Herein we report on a scalable approach to the direct wet deposition of zeolite thin films and membranes while maintaining a high degree of control over the preferred crystal orientation. As a proof of concept, thin films comprising aluminophosphate zeolite AEI were cast on silicon wafer or porous alumina substrates. Electrical properties and separation performance of the zeolite thin films/membranes were engineered through controlling degree of preferred crystal orientation.
Spontaner metallfreier Wasserstofftransfer zwischen Amminboranen und Iminoboranen
Authors: Winner Lena , Ewing William C. , Geetharani K. , Dellermann Theresa , Jouppi Brian , Kupfer Thomas , Schäfer Marius , Braunschweig Holger 
Published: August 2018

AbstractWir berichten hier über den ersten spontanen und metallfreien Wasserstofftransfer zwischen Amminboran (NH3BH3) und Iminoboranen bei Raumtemperatur. DFT‐Rechnungen belegen einen konzertierten H+/H−‐Transfer von NH3BH3 mit einer Aktivierungsenergie weit unter der vergleichbarer Wasserstoffübertragungsreaktionen. Zudem konnten durch Umsetzung von Iminoboranen mit Amminboranen neue B,N‐disubstituierte Aminoborane isoliert werden, von denen bisher nur wenige Vertreter bekannt sind. Dieser erfolgreiche Wasserstofftransfer zu einem dehydrierten BN‐System könnte ein Ansatzpunkt für die Entwicklung neuartiger Systeme für Dehydrierungs‐ bzw. Rehydrierungsprozesse sein.
Site‐Selective Remote Radical C−H Functionalization of Unactivated C−H Bonds in Amides Using Sulfone Reagents
Authors: Xia Yong , Wang Lin , Studer Armido 
Published: August 2018

AbstractA general and practical strategy for remote site‐selective functionalization of unactivated aliphatic C−H bonds in various amides by radical chemistry is introduced. C−H bond functionalization is achieved by using the readily installed N‐allylsulfonyl moiety as an N‐radical precursor. The in situ generated N‐radical engages in intramolecular 1,5‐hydrogen atom transfer to generate a translocated C radical which is subsequently trapped with various sulfone reagents to afford the corresponding C−H functionalized amides. The generality of the approach is documented by the successful remote C−N3, C−Cl, C−Br, C−SCF3, C−SPh, and C−C bond formation. Unactivated tertiary and secondary C−H bonds, as well as activated primary C−H bonds, can be readily functionalized by this method.
Total Synthesis of Epicolactone
Authors: Kravina Alberto G. , Carreira Erick M. 
Published: August 2018

AbstractThe biologically active and structurally complex secondary metabolite epicolactone is a member of the natural product pool found in cash crop endophytes of the genus Epicoccum. By exploiting inherent reactivity, a total synthesis of this highly oxygenated and polycyclic molecule met chemo‐ and regioselectivity challenges. The key buildup of complexity was accomplished via an intramolecular [2+2] photocycloaddition between a quinone and an electron‐deficient diene followed by a cyclobutane ring expansion. The use of a dioxene as an acyl anion equivalent and an intramolecular carbonyl methenylation furnished the natural product.
Straightforward α‐Amino Nitrile Synthesis Through Mo(CO)6‐Catalyzed Reductive Functionalization of Carboxamides
Authors: Trillo Paz , Slagbrand Tove , Adolfsson Hans 
Published: August 2018

AbstractThe selective reduction of amides into an intermediate hemiaminal catalyzed by Mo(CO)6 together with the inexpensive and easy to handle TMDS (1,1,3,3‐tetramethyldisiloxane) as reducing agent, followed by subsequent trapping of the hemiaminal with a cyanide source, allows for the straightforward synthesis of α‐amino nitriles. The methodology presented here, displays high levels of chemoselectivity allowing for the reduction of amides in the presence of functional groups such as ketones, imines, aldehydes, and acids, which affords a simple route for the synthesis of α‐amino nitriles with a broad scope of functionalities in high yields. Furthermore, the applicability of this methodology is demonstrated by scale up experiments and by derivatization of the target compounds into synthetically interesting products. The selective cyanation is successfully applied in late stage functionalizations of amide containing drugs and prolinol derivatives.
Die lokalen Aktivitäten von Hydroxidionen und Wasser bestimmen die Funktionsweise von auf Silber basierenden Sauerstoffverzehrkathoden
Authors: Botz Alexander , Clausmeyer Jan , Öhl Denis , Tarnev Tsvetan , Franzen David , Turek Thomas , Schuhmann Wolfgang 
Published: August 2018

AbstractLokale Änderungen der Ionenaktivitäten an der Oberfläche einer arbeitenden Sauerstoffverzehrkathode (SVK) wurden mittels elektrochemischer Rastermikroskopie gemessen. Während die SVK OH−‐Ionen unter Konsum von H2O durch elektrokatalytische Reduktion von O2 produziert, werden die Änderungen in den Ionenaktivitäten über eine positionierte Pt‐Mikroelektrode bestimmt. Die Empfindlichkeit der Platinelektrode wird durch die pH‐abhängige Reduktion von PtO gewährleistet. Dadurch kann auf eine vorherige Modifikation der Elektrode verzichtet werden. Diese Technik ermöglicht es, Änderungen der Koordination von H2O und OH−‐Ionen darzustellen sowie die lokale katalytische Aktivität zu evaluieren. Damit wird gezeigt, dass die elektrochemische Reaktion an sehr aktiven Katalysatoren einen starken Einfluss auf die Reaktionsumgebung haben kann.
The Crucial Role of Chlorinated Thiophene Orientation in Conjugated Polymers for Photovoltaic Devices
Authors: Wu Yanan , An Cunbin , Shi Lanlan , Yang Liyan , Qin Yunpeng , Liang Ningning , He Chang , Wang Zhaohui , Hou Jianhui 
Published: August 2018

AbstractChlorinated conjugated polymers not only show great potential for the realization of highly efficient polymer solar cells (PSCs) but also have simple and high‐yield synthetic routes and low‐cost raw materials available for their preparation. However, the study of the structure–property relationship of chlorinated polymers is lagging. Now two chlorinated conjugated polymers, PCl(3)BDB‐T and PCl(4)BDB‐T are investigated. When the polymers were used to fabricate PSCs with the nonfullerene acceptor (IT‐4F), surprisingly, the PCl(3)BDB‐T:IT‐4F‐based device exhibited a negligible power conversion efficiency (PCE) of 0.18 %, while the PCl(4)BDB‐T:IT‐4F‐based device showed an outstanding PCE of 12.33 %. These results provide new insight for the rational design and synthesis of novel chlorinated polymer donors for further improving the photovoltaic efficiencies of PSCs.
Direct Conversion of Alcohols into Alkenes by Dehydrogenative Coupling with Hydrazine/Hydrazone Catalyzed by Manganese
Authors: Das Uttam Kumar , Chakraborty Subrata , Diskin‐Posner Yael , Milstein David 
Published: August 2018

AbstractWe have developed unprecedented methods for the direct transformation of primary alcohols to alkenes in the presence of hydrazine, and for the synthesis of mixed alkenes by the reaction of alcohols with hydrazones. The reactions are catalyzed by a manganese pincer complex and proceed in absence of added base or hydrogen acceptors, liberating dihydrogen, dinitrogen, and water as the only byproducts. The proposed mechanism, based on preparation of proposed intermediates and control experiments, suggests that the transformation occurs through metal–ligand cooperative N−H activation of a hydrazone intermediate.
An Extremely Simple Method for Protecting Lithium Anodes in Li‐O2 Batteries
Authors: Zhang Xin , Zhang Qinming , Wang Xin‐Gai , Wang Chengyi , Chen Ya‐Nan , Xie Zhaojun , Zhou Zhen 
Published: August 2018

AbstractRechargeable Li‐O2 batteries have aroused much attention for their high energy density as a promising battery technology; however, the performance of the batteries is still unsatisfactory. Lithium anodes, as one of the most important part of Li‐O2 batteries, play a vital role in improving the cycle life of the batteries. Now, a very simple method is introduced to produce a protective film on lithium surface via chemical reactions between lithium metals and 1,4‐dioxacyclohexane. The film is mainly composed of ethylene oxide monomers and endows Li‐O2 batteries with enhanced cycling stability. The film could effectually reduce the morphology changes and suppress the parasitic reactions of lithium anodes. This simple approach provides a new strategy to protect lithium anodes in Li‐O2 batteries.
Two‐Dimensional Tellurium Nanosheets Exhibiting an Anomalous Switchable Photoresponse with Thickness Dependence
Authors: Peng Jing , Pan Yu , Yu Zhi , Wu Jiajing , Wu Junchi , Zhou Yuan , Guo Yuqiao , Wu Xiaojun , Wu Changzheng , Xie Yi 
Published: August 2018

AbstractTwo‐dimensional (2D) tellurium (Te) was recently predicted to be promising for diverse electronic and optoelectronic applications. However, the synthesis of high‐quality 2D Te structures remains challenging, which greatly hinders the exploration of its full properties. Herein, an anomalous photoresponse from negative to positive as a function of thickness in Te nanosheets is reported. Ultrathin Te layers with large size and clean interface were obtained through a topotactic transformation, in which the 2D Te structure was derived from a layered MTe2 (M=Ti, Mo, W) matrix by excessive lithiation. Prominently, the photoresponse in Te nanosheets exhibits negative behavior when the thickness is less than 5 nm, which turns positive as the thickness increases. This unusual photoresponse will shed light on the full exploration of 2D non‐layered materials with exotic properties.
Ein neutraler η5‐Aminoborol‐Germanium(II)‐Komplex
Authors: Tholen Patrik , Dong Zhaowen , Schmidtmann Marc , Albers Lena , Müller Thomas 
Published: August 2018

AbstractDie Synthese von zwei η5‐Aminoborol‐Germanium(II)‐Komplexen aus der Reaktion eines Germoldianions mit Aminobordichloriden wird beschrieben. Diese Reaktion liefert ein bemerkenswertes Beispiel für eine Germol‐zu‐Borol‐Transformation. Die beiden Aminoborol‐Germanium(II)‐Komplexe wurden vollständig durch Heterokern‐NMR‐, IR‐Spektroskopie, HR‐Massenspektrometrie und in einem Fall durch Röntgenkristallographie charakterisiert. Die Ergebnisse quantenmechanischer Rechnungen favorisieren die elektronische Struktur eines Halbsandwich‐Komplexes von GeII gegenüber einer ionischen Darstellung eines Germanium‐Dikations, welches durch ein aromatisches Aminoboroldianion stabilisiert wird.
Eine kurze Totalsynthese von Ajoen
Authors: Silva Filipa , Khokhar Shaista S. , Williams Danielle M. , Saunders Robert , Evans Gareth J. S. , Graz Michael , Wirth Thomas 
Published: August 2018

AbstractWir beschreiben eine kurze Totalsynthese von Ajoen, einem wichtigen biologisch aktiven Bestandteil von Knoblauch. Die Instabilität von Allicin, dem einzigen bekannten alternativen Ausgangsmaterial, hat zur Entwicklung eines zuverlässigen Protokolls für die Synthese von Ajoen aus einfachen Bausteinen geführt, welches sich auch für größere Mengen eignet.
Nickel‐Catalyzed Enantioconvergent Borylation of Racemic Secondary Benzylic Electrophiles
Authors: Wang Zhaobin , Bachman Shoshana , Dudnik Alexander S. , Fu Gregory C. 
Published: August 2018

AbstractNickel‐catalyzed cross‐coupling has emerged as the most versatile approach to date for achieving enantioconvergent carbon–carbon bond formation using racemic alkyl halides as electrophiles. In contrast, there have not yet been reports of the application of chiral nickel catalysts to the corresponding reactions with heteroatom nucleophiles to produce carbon–heteroatom bonds with good enantioselectivity. Herein, we establish that a chiral nickel/pybox catalyst can borylate racemic secondary benzylic chlorides to provide enantioenriched benzylic boronic esters, a highly useful family of compounds in organic synthesis. The method displays good functional group compatibility (e.g., being unimpeded by the presence of an indole, a ketone, a tertiary amine, or an unactivated alkyl bromide), and both of the catalyst components (NiCl2⋅glyme and the pybox ligand) are commercially available.
Spontaneous Metal‐Free Transfer Hydrogenation of Iminoboranes with Ammonia Borane and Amine Boranes
Authors: Winner Lena , Ewing William C. , Geetharani K. , Dellermann Theresa , Jouppi Brian , Kupfer Thomas , Schäfer Marius , Braunschweig Holger 
Published: August 2018

AbstractThe first spontaneous, metal‐free, room‐temperature hydrogen transfer from ammonia borane to an iminoborane is reported. Mechanistic studies of the reaction indicate a concerted transfer of H+ and H− from donor to acceptor with an activation energy far below those of comparable concerted transfer hydrogenations. This reaction was employed in the syntheses and isolation of new B,N‐disubstituted aminoboranes, a comparatively rare subset within the aminoborane family. This successful transfer hydrogenation to a highly dehydrogenated BN system may serve as a starting point for the design of new systems capable of reversible dehydrogenation/rehydrogenation.
Photoinduced Remote Functionalization of Amides and Amines Using Electrophilic Nitrogen Radicals
Authors: Morcillo Sara P. , Dauncey Elizabeth M. , Kim Ji Hye , Douglas James J. , Sheikh Nadeem S. , Leonori Daniele 
Published: August 2018

AbstractThe selective functionalization of C(sp3)−H bonds at distal positions to functional groups is a challenging task in synthetic chemistry. Reported here is a photoinduced radical cascade strategy for the divergent functionalization of amides and protected amines. The process is based on the oxidative generation of electrophilic amidyl radicals and their subsequent transposition by 1,5‐H‐atom transfer, resulting in remote fluorination, chlorination and, for the first time, thioetherification, cyanation, and alkynylation. The process is tolerant of most common functional groups and delivers useful building blocks that can be further elaborated. The utility of this strategy is demonstrated through the late‐stage functionalization of amino acids and a dipeptide.
A Neutral η5‐Aminoborole Complex of Germanium(II)
Authors: Tholen Patrik , Dong Zhaowen , Schmidtmann Marc , Albers Lena , Müller Thomas 
Published: August 2018

AbstractThe synthesis of two η5‐aminoborole complexes of germanium(II) from the reaction of a germole dianion with aminoboron dichlorides is reported. This reaction constitutes a remarkable example of a germole‐to‐borole transformation. The two aminoborole complexes of germanium(II) were fully characterized by multinuclear NMR spectroscopy, IR spectroscopy, HRMS, and, in one case, by X‐ray crystallography. The results of quantum‐mechanical calculations favor the electronic structure of a half‐sandwich complex of GeII over an ionic representation with a germanium dication stabilized by an aromatic aminoborole dianion.
A new polymer field effect transistor based on fluorene derivative with fused furan rings
Authors: He Yang , Xiao Mingchao , Liu Ye , Zhang Xi , Jiang Lang , Liu Hui , Zou Yingping 
Published: August 2018

ABSTRACTComposed of novel monomer (10,10‐dihexyl‐10‐fluoreno[2,3‐b:7,6‐b′]difuran‐2,7‐diyl)bis(tri‐methylstannane) (DFF) and commercial 2,5‐di(2‐ethylhexyl)‐3,6‐di(5‐bromothiophen‐2‐yl)diketopyrrolopyrrole (DPP32), PDFFDPP32 is synthesized and systematically characterized by high‐temperature gel‐permeation chromatography, thermogravimetric analysis, ultraviolet–visible absorption, Fourier transform infrared spectroscopy, and cyclic voltammetry testing. The resulting polymer displays good hole transport behaviors in bottom gate/top contact organic field effect transistors (OFET) with hole mobility up to 6.42 × 10−3 cm2 V−1 s−1. The rough surface morphology of the polymer films is characterized by atomic force microscopy, and the polymer films are in an amorphous state, as demonstrated by X‐ray diffraction. The intra‐ and interchain O···S noncovalent interactions, as verified by X‐ray photoelectron spectroscopy, possibly endow the polymer with enhanced interactive forces among the polymeric chains. The results indicate that PDFFDPP32 has potential applications in OFET, and the novel monomer DFF has prospects for building high‐performance organic optoelectronic materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46865
Effect of electronegativity and steric hindrance of the cocatalyst on the activity and selectivity of butadiene polymerization catalyzed by molybdenum
Authors: Liu Jinhui , Geng Jieting , Liu Kai , Zou Lingli , Wang Zhaobo , Hua Jing 
Published: August 2018

ABSTRACTMolybdenum‐based random 1,2‐polybutadiene (1,2‐PB) rubber, with its excellent wet skid resistance, low rolling resistance, and low heat buildup, can be used for green tread rubber, and it has significant benefits for the enhancement of the mechanical strength of 1,2‐PB. In this study, we investigated in detail the effects of the electronegativity and steric hindrance of the cocatalyst on the stereoselectivity of the resulting polymers. In the case of cocatalysts with moderate electronegativities, the active centers were more stable; this resulted in a larger molecular weight and a higher conversion, whereas a cocatalyst with excessive electronegativity tended to initiate cationic polymerization. The high sterically hindered substituent restricted the coordination configuration of the monomer; this ultimately resulted in the increase in the 1,2 structure to 90%. Fourier transform infrared analysis showed that the content of trans‐1,4 structure increased from 7 to 66%, and its crystallinity reached 59.2%, as calculated with differential scanning calorimetry when triethyl aluminum was used as the cocatalyst. Consequently, trans‐1,4‐polybutadiene crystals were introduced into the 1,2‐PB elastomer in one step; this could be a promising facile route for strengthening 1,2‐PB. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46906.
Influence of solubility parameter difference between monomer and porogen on structures of poly (acrylonitrile–styrene‐divinylbenzene) resins
Authors: Cai Yuanbo , Yan Wu , Peng Xuesong , Liang Mei , Yu Lin , Zou Huawei 
Published: August 2018

ABSTRACTIn this work, the acrylonitrile (AN)‐styrene (St)‐divinylbenzene (DVB) resin was synthesized via suspension polymerization in the presence of inert porogens as diluent. The relationship of the solubility parameter (SP) of the materials and the porous properties of the resin was investigated. These porous spherical resin particles (0.25–0.84 mm) can be used as precursors of amidoxime resin which has a high metal ion chelating efficiency. The results showed that the porous properties (surface area and mean pore width) of the resin changed with variation in the compatibility between monomers and porogens. According to the the BET theory to N2 sorption and scanning electron microscopy (SEM), the specific surface area of the obtained beads was strongly dependent on the compatibility of the components of the system and achieved values from 3.3 to 66.8 m2/g. The surface area of the terpolymer beads was found to rise with a decrease in the content of acrylonitrile or an increase in the SP of the porogens. However, the variation of the pore size was just the opposite. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46979.