bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Synthesis of Enantiomeric η6‐Arene Chromium Tricarbonyl Complexes with Epimeric Pyrroloimidazolones
Authors: Wilson‐Konderka Cody , Doxtator Kathleen , Metallinos Costa 
Published: August 2016

AbstractA pair of epimeric l‐proline derived chiral auxiliaries have been developed for the diastereoselective lithiation–substitution of η6‐arene chromium tricarbonyl complexes. Lithiation of the anti epimer affords planar chiral imidazolones in >95:5 dr upon electrophile quench. Application of the same reaction sequence to the syn epimer provides products with opposite planar chirality in equally high levels of diastereomeric purity. The ortho‐substituted epimeric imidazolones give rise to planar chiral enantiomers upon acid‐induced elimination, thus precluding the need to prepare a d‐proline‐derived starting material.magnified image
Enantioselective Copper‐Catalyzed Intramolecular N−H Bond Insertion: Synthesis of Chiral 2‐Carboxytetrahydroquinolines
Authors: Song Xiao‐Guang , Ren Yuan‐Yuan , Zhu Shou‐Fei , Zhou Qi‐Lin 
Published: August 2016

AbstractThe first highly enantioselective intramolecular N−H bond insertion was realized by using copper catalysts modified with chiral spirobisoxazoline ligands, which provides a novel strategy for the synthesis of chiral 2‐carboxytetrahydroquinolines. This reaction features fast reaction rate, high yield, high enantioselectivity, and mild reaction conditions.magnified image
Sodium Iodide/Hydrogen Peroxide‐Mediated Oxidation/Lactonization for the Construction of Spirocyclic Oxindole‐Lactones
Authors: Li Guofeng , Huang Liwu , Xu Jiecheng , Sun Wangsheng , Xie Junqiu , Hong Liang , Wang Rui 
Published: August 2016

AbstractThe sodium iodide/hydrogen peroxide‐mediated oxidation/lactonization of indolepropionic acids was achieved, affording the corresponding spirocyclic oxindole‐lactones in moderate to high yields. This metal‐free procedure features mild reaction conditions, non‐toxicity and easy handling, with hydrogen peroxide (H2O2) as a clean oxidant.magnified image
Femtosecond Hydrogen Bond Dynamics of Bulk‐like and Bound Water at Positively and Negatively Charged Lipid Interfaces Revealed by 2D HD‐VSFG Spectroscopy
Authors: Singh Prashant Chandra , Inoue Ken‐ichi , Nihonyanagi Satoshi , Yamaguchi Shoichi , Tahara Tahei 
Published: August 2016

AbstractInterfacial water in the vicinity of lipids plays an important role in many biological processes, such as drug delivery, ion transportation, and lipid fusion. Hence, molecular‐level elucidation of the properties of water at lipid interfaces is of the utmost importance. We report the two‐dimensional heterodyne‐detected vibrational sum frequency generation (2D HD‐VSFG) study of the OH stretch of HOD at charged lipid interfaces, which shows that the hydrogen bond dynamics of interfacial water differ drastically, depending on the lipids. The data indicate that the spectral diffusion of the OH stretch at a positively charged lipid interface is dominated by the ultrafast (<∼100 fs) component, followed by the minor sub‐picosecond slow dynamics, while the dynamics at a negatively charged lipid interface exhibit sub‐picosecond dynamics almost exclusively, implying that fast hydrogen bond fluctuation is prohibited. These results reveal that the ultrafast hydrogen bond dynamics at the positively charged lipid–water interface are attributable to the bulk‐like property of interfacial water, whereas the slow dynamics at the negatively charged lipid interface are due to bound water, which is hydrogen‐bonded to the hydrophilic head group.
Direct Monitoring of γ‐Glutamyl Transpeptidase Activity In Vivo Using a Hyperpolarized 13C‐Labeled Molecular Probe
Authors: Nishihara Tatsuya , Yoshihara Hikari A. I. , Nonaka Hiroshi , Takakusagi Yoichi , Hyodo Fuminori , Ichikawa Kazuhiro , Can Emine , Bastiaansen Jessica A. M. , Takado Yuhei , Comment Arnaud , Sando Shinsuke 
Published: August 2016

AbstractThe γ‐glutamyl transpeptidase (GGT) enzyme plays a central role in glutathione homeostasis. Direct detection of GGT activity could provide critical information for the diagnosis of several pathologies. We propose a new molecular probe, γ‐Glu‐[1‐13C]Gly, for monitoring GGT activity in vivo by hyperpolarized (HP) 13C magnetic resonance (MR). The properties of γ‐Glu‐[1‐13C]Gly are suitable for in vivo HP 13C metabolic analysis since the chemical shift between γ‐Glu‐[1‐13C]Gly and its metabolic product, [1‐13C]Gly, is large (4.3 ppm) and the T1 of both compounds is relatively long (30 s and 45 s, respectively, in H2O at 9.4 T). We also demonstrate that γ‐Glu‐[1‐13C]Gly is highly sensitive to in vivo modulation of GGT activity induced by the inhibitor acivicin.
Struktureller Nachweis des ersten Polychloriddianions: Untersuchung von [Cl8]2−
Authors: Brückner Robin , Pröhm Patrick , Wiesner Anja , Steinhauer Simon , Müller Carsten , Riedel Sebastian 
Published: August 2016

AbstractDas Polychloridsalz [CCl(NMe2)2]+2[Cl8]2− wurde in der ionischen Flüssigkeit [BMP]OTf synthetisiert und kristallisiert. Die Verbindung wurde mittels Raman‐Spektroskopie und Einkristallröntgenstrukturanalyse vollständig charakterisiert und enthält das erste literaturbekannte Polychloriddianion. Des Weiteren wurden detaillierte Gasphasen‐ und Festkörperrechnungen bezüglich der Bindungssituation durchgeführt.
Direct Catalytic Asymmetric Mannich Reaction with Dithiomalonates as Excellent Mannich Donors: Organocatalytic Synthesis of (R)‐Sitagliptin
Authors: Bae Han Yong , Kim Mun Jong , Sim Jae Hun , Song Choong Eui 
Published: August 2016

AbstractIn this study, dithiomalonates (DTMs) were demonstrated to be exceptionally efficient Mannich donors in terms of reactivity and stereoselectivity in cinchona‐based‐squaramide‐catalyzed enantioselective Mannich reactions of diverse imines or α‐amidosulfones as imine surrogates. Owing to the superior reactivity of DTMs as compared to conventional malonates, the catalyst loading could be reduced to 0.1 mol % without the erosion of enantioselectivity (up to 99 % ee). Furthermore, by the use of a DTM, even some highly challenging primary alkyl α‐amidosulfones were smoothly converted into the desired adducts with excellent enantioselectivity (up to 97 % ee), whereas the use of a malonate or monothiomalonate resulted in no reaction under identical conditions. The synthetic utility of the chiral Mannich adducts obtained from primary alkyl substrates was highlighted by the organocatalytic, coupling‐reagent‐free synthesis of the antidiabetic drug (−)‐(R)‐sitagliptin.
A Multinuclear Metal Complex Based DNase‐Mimetic Artificial Enzyme: Matrix Cleavage for Combating Bacterial Biofilms
Authors: Chen Zhaowei , Ji Haiwei , Liu Chaoqun , Bing Wei , Wang Zhenzhen , Qu Xiaogang 
Published: August 2016

AbstractExtracellular DNA (eDNA) is an essential structural component during biofilm formation, including initial bacterial adhesion, subsequent development, and final maturation. Herein, the construction of a DNase‐mimetic artificial enzyme (DMAE) for anti‐biofilm applications is described. By confining passivated gold nanoparticles with multiple cerium(IV) complexes on the surface of colloidal magnetic Fe3O4 /SiO2 core/shell particles, a robust and recoverable artificial enzyme with DNase‐like activity was obtained, which exhibited high cleavage ability towards both model substrates and eDNA. Compared to the high environmental sensitivity of natural DNase in anti‐biofilm applications, DMAE exhibited a much better operational stability and easier recoverability. When DMAE was coated on substratum surfaces, biofilm formation was inhibited for prolonged periods of time, and the DMAE excelled in the dispersion of established biofilms of various ages. Finally, the presence of DMAE remarkably potentiated the efficiency of traditional antibiotics to kill biofilm‐encased bacteria and eradiate biofilms.
Stabilization of a Chiral Dirhodium Carbene by Encapsulation and a Discussion of the Stereochemical Implications
Authors: Werlé Christophe , Goddard Richard , Philipps Petra , Farès Christophe , Fürstner Alois 
Published: August 2016

AbstractFor the first time, the stereochemical course of an asymmetric cyclopropanation can be discussed on the basis of experimental structural information on a pertinent chiral dirhodium carbene intermediate. Key to success was the formation of racemic single crystals of a heterochiral [Rh2{(S*)‐PTTL}4{=C(Ar)COOMe}][Rh2{(R*)‐PTTL}4] (Ar=MeOC6H4; PTTL=N‐phthaloyl‐tert‐leucinate) capsule, which has been characterized by X‐ray diffraction. NMR spectroscopic data confirm that the obtained structural portrait is also relevant in solution and provide additional information about the dynamics of this species. The chiral binding pocket is primarily defined by the conformational preferences of the N‐phthaloyl‐protected amino acid ligands and reinforced by a network of weak interligand interactions that get stronger when chlorinated phthalimide residues are used.
Coke Formation in a Zeolite Crystal During the Methanol‐to‐Hydrocarbons Reaction as Studied with Atom Probe Tomography
Authors: Schmidt Joel E. , Poplawsky Jonathan D. , Mazumder Baishakhi , Attila Özgün , Fu Donglong , de Winter D. A. Matthijs , Meirer Florian , Bare Simon R. , Weckhuysen Bert M. 
Published: August 2016

AbstractUnderstanding the formation of carbon deposits in zeolites is vital to developing new, superior materials for various applications, including oil and gas conversion processes. Herein, atom probe tomography (APT) has been used to spatially resolve the 3D compositional changes at the sub‐nm length scale in a single zeolite ZSM‐5 crystal, which has been partially deactivated by the methanol‐to‐hydrocarbons reaction using 13C‐labeled methanol. The results reveal the formation of coke in agglomerates that span length scales from tens of nanometers to atomic clusters with a median size of 30–60 13C atoms. These clusters correlate with local increases in Brønsted acid site density, demonstrating that the formation of the first deactivating coke precursor molecules occurs in nanoscopic regions enriched in aluminum. This nanoscale correlation underscores the importance of carefully engineering materials to suppress detrimental coke formation.
Structural Proof for the First Dianion of a Polychloride: Investigation of [Cl8]2−
Authors: Brückner Robin , Pröhm Patrick , Wiesner Anja , Steinhauer Simon , Müller Carsten , Riedel Sebastian 
Published: August 2016

AbstractThe polychloride salt [CCl(NMe2)2]+2[Cl8]2− was synthesized and crystallized in the ionic liquid [BMP]OTf. The compound was fully characterized by Raman spectroscopy as well as X‐ray single‐crystal structure determination, and represents the first example of a polychloride dianion to be described. Detailed gas‐phase and solid‐state calculations concerning the nature of the bonding situation were also performed.
Coke Formation in a Zeolite Crystal During the Methanol‐to‐Hydrocarbons Reaction as Studied with Atom Probe Tomography
Authors: Schmidt Joel E. , Poplawsky Jonathan D. , Mazumder Baishakhi , Attila Özgün , Fu Donglong , de Winter D. A. Matthijs , Meirer Florian , Bare Simon R. , Weckhuysen Bert M. 
Published: August 2016

AbstractUnderstanding the formation of carbon deposits in zeolites is vital to developing new, superior materials for various applications, including oil and gas conversion processes. Herein, atom probe tomography (APT) has been used to spatially resolve the 3D compositional changes at the sub‐nm length scale in a single zeolite ZSM‐5 crystal, which has been partially deactivated by the methanol‐to‐hydrocarbons reaction using13C‐labeled methanol. The results reveal the formation of coke in agglomerates that span length scales from tens of nanometers to atomic clusters with a median size of 30–6013C atoms. These clusters correlate with local increases in Brønsted acid site density, demonstrating that the formation of the first deactivating coke precursor molecules occurs in nanoscopic regions enriched in aluminum. This nanoscale correlation underscores the importance of carefully engineering materials to suppress detrimental coke formation.
Influence of dynamic crosslinking on the morphology, crystallization, and dynamic mechanical properties of PA6,12/EVA blends
Authors: Bondan Fabrício , Ernzen Juliano Roberto , Amalvy Javier , Machado Ana Vera , Nardi Martins Johnny De , Bianchi Otávio 
Published: August 2016

ABSTRACTThis study investigated the effect of dynamic crosslinking of polyamide 6,12 and random copolymers of ethylene and vinyl acetate blends (PA6,12/EVA) on the morphology, crystallinity, and dynamic mechanical properties. The crosslinking agent was dicumyl peroxide (DCP), and the blends were processed in a torque rheometer. The morphology depended on the DCP content, and all blends exhibited the same crystallinity index. However, with increasing crosslinking degree, the interfacial tackiness (E) values increased from 1.8 to 2.7 nm. The lamellar structures of all blends started forming at approximately 160 °C, close to the temperature of pure polyamide. The crosslinked phase enhanced the pseudo‐elastic behavior of the blends and increased their molecular mobility activation energy. Samples with higher crosslinking degree exhibited smaller permanent deformation (0.01%) than those with low crosslinking. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44206.
Large‐scale integration of flexible materials into rolled and corrugated thermoelectric modules
Authors: Fang Haiyu , Popere Bhooshan C. , Thomas Elayne M. , Mai Cheng‐Kang , Chang William B. , Bazan Guillermo C. , Chabinyc Michael L. , Segalman Rachel A. 
Published: August 2016

ABSTRACTOrganic materials are promising candidates for thermoelectric applications owing to their tunable structure and therefore, properties, low cost, earth abundance, and solution processability. Conventional thermoelectric module architecture that relies on relatively thick (∼ mm) “legs” has limited the incorporation of organics into scalable modules. Herein, we report the fabrication of thermoelectric modules based on organic thermoelectric materials consisting of 100 or more p‐ and n‐legs. This approach utilizes an innovative rolled module design that is shown to easily maintain a temperature gradient above 50 K in the axial direction. Rolled modules comprising PEDOT:PSS (p‐type) and nickel (n‐type) material system with 288 legs were shown to produce an open circuit voltage and a power output of 260 mV and 46 μW, respectively at a temperature difference of 65 K. We note that the thermoelectric power generated by such modules is sufficient to simultaneously light up nine blue LEDs after boosting the output voltage with a voltage step up converter. We also demonstrate the versatility of this approach by fabricating corrugated modules, which enables facile module assembly onto rigid (polylactic acid, PLA) or flexible (polydimethylsiloxane, PDMS) substrates, without significant loss in the power output compared to the rolled modules. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44208.
High‐Resolution Magnetic Resonance Imaging of Scalp Arteries for the Diagnosis of Giant Cell Arteritis: Results of a Prospective Cohort Study
Authors: Rhéaume Maxime , Rebello Ryan , Pagnoux Christian , Carette Simon , Clements‐Baker Marie , Cohen‐Hallaleh Violette , Doucette‐Preville David , Stanley Jackson B. , Salama Sargious Salama Samih , Ioannidis George , Khalidi Nader A. 
Published: August 2016

ObjectiveTo examine the concordance between high‐resolution magnetic resonance imaging (MRI) of the scalp arteries and temporal artery biopsy for the diagnosis of giant cell arteritis (GCA).MethodsWe conducted a prospective cohort study of patients with suspected GCA. Participants underwent high‐field 3T MRI of the scalp arteries followed by temporal artery biopsy. Arterial wall thickness and enhancement on multiplanar postcontrast T1‐weighted spin‐echo images were graded according to a published severity scale (range 0–3). MRI findings were compared with temporal artery biopsy results and the American College of Rheumatology (ACR) criteria for GCA.ResultsOne hundred seventy‐one patients were included in the study. Temporal artery biopsy findings were positive in 31 patients (18.1%), and MRI findings were abnormal in 60 patients (35.1%). ACR criteria were met in 137 patients (80.1%). With temporal artery biopsy as the reference test, MRI had a sensitivity of 93.6% (95% confidence interval [95% CI] 78.6–99.2) and a specificity of 77.9% (95% CI 70.1–84.4). The corresponding negative predictive value of MRI was 98.2% (95% CI 93.6–99.8) and positive predictive value was 48.3% (95% CI 35.2–61.6).ConclusionIn patients with suspected GCA, normal findings on scalp artery MRI are very strongly associated with negative temporal artery biopsy findings. This suggests that MRI could be used as the initial diagnostic procedure in GCA, with temporal artery biopsy being reserved for patients with abnormal MRI findings.
Histone Deacetylase 5 Is Overexpressed in Scleroderma Endothelial Cells and Impairs Angiogenesis via Repression of Proangiogenic Factors
Authors: Tsou Pei‐Suen , Wren Jonathan D. , Amin M. Asif , Schiopu Elena , Fox David A. , Khanna Dinesh , Sawalha Amr H. 
Published: August 2016

ObjectiveVascular dysfunction represents a disease‐initiating event in systemic sclerosis (SSc; scleroderma). Results of recent studies suggest that epigenetic dysregulation impairs normal angiogenesis and can result in abnormal patterns of blood vessel growth. Histone deacetylases (HDACs) control endothelial cell (EC) proliferation and regulate EC migration. Specifically, HDAC‐5 appears to be antiangiogenic. This study was undertaken to test whether HDAC‐5 contributes to impaired angiogenesis in SSc by repressing proangiogenic factors in ECs.MethodsDermal ECs were isolated from patients with diffuse cutaneous SSc and healthy controls. Angiogenesis was assessed using an in vitro Matrigel tube formation assay. An assay for transposase‐accessible chromatin using sequencing (ATAC‐seq) was performed to assess and localize the genome‐wide effects of HDAC5 knockdown on chromatin accessibility.ResultsThe expression of HDAC5 was significantly increased in ECs from patients with SSc compared to healthy control ECs. Silencing of HDAC5 in SSc ECs restored normal angiogenesis. HDAC5 knockdown followed by ATAC‐seq assay in SSc ECs identified key HDAC5‐regulated genes involved in angiogenesis and fibrosis, such as CYR61, PVRL2, and FSTL1. Simultaneous knockdown of HDAC5 in conjunction with either CYR61, PVRL2, or FSTL1 inhibited angiogenesis in SSc ECs. Conversely, overexpression of these genes individually led to an increase in tube formation as assessed by Matrigel assay, suggesting that these genes play functional roles in the impairment of angiogenesis in SSc.ConclusionSeveral novel HDAC5‐regulated target genes associated with impaired angiogenesis were identified in SSc ECs by ATAC‐seq. The results of this study provide a potential link between epigenetic regulation and impaired angiogenesis in SSc, and identify a novel mechanism for the dysregulated angiogenesis that characterizes this disease.
Comparative Study of Bifunctional Mononuclear and Dinuclear Amidoiridium Complexes with Chiral C−N Chelating Ligands for the Asymmetric Transfer Hydrogenation of Ketones
Authors: Sato Yasuhiro , Kayaki Yoshihito , Ikariya Takao 
Published: August 2016

AbstractA series of new bifunctional C−N chelating Ir complexes possessing a metal/NH group was synthesized by cyclometalation of optically active primary benzylic amines such as O‐silylated (S)‐2‐amino‐2‐phenylethanols (1 a and 1 a’), (R)‐5‐amino‐6,7,8,9‐tetrahydro‐5H‐benzocycloheptene (1 b), and (R)‐1‐phenyl‐2,2‐dimethylpropylamine (1 c). Although treatment of KOtBu with the amine complexes originating from 1 a and 1 a’ afforded amido‐bridged dinuclear complexes (3 a and 3 a’), more sterically hindered complexes were solely transformed into the coordinatively unsaturated mononuclear amido complexes (3 b and 3 c), which can serve as real catalyst species in the asymmetric transfer hydrogenation. The structural difference in the C−N chelate framework markedly affected the catalytic performance. Among them, amido complex 3 c showed a pronounced ability to catalyze the transfer hydrogenation of acetophenone in 2‐propanol, even at a low temperature of −30 °C. A hydridoiridium complex (4 c) was also identified in the reaction of 3 c in 2‐propanol, which provides mechanistic insights into the enantiodiscriminating step in the hydrogen transfer to prochiral ketones.
Modeling and solving discrete network design problem with stochastic user equilibrium
Authors: Liu Haoxiang , Wang David Z. W. 
Published: August 2016

SummaryIn this paper, we address the discrete network design problem, which determines the addition of new roads to existing transportation network to optimize the transportation system performance. Road users are assumed to follow the traffic assignment principle of stochastic user equilibrium. A mixed‐integer nonlinear nonconvex problem is developed to model this discrete network design problem with stochastic user equilibrium. The original problem is relaxed into a convex mixed‐integer nonlinear program, whose solution provides a lower bound of the original problem. The relaxed problem is then embedded into two proposed global optimization solution algorithms to obtain the global optimal solution of the problem. Copyright © 2016 John Wiley & Sons, Ltd.
Metallocorroles as Non‐Precious Metal Electrocatalysts for Highly Efficient Oxygen Reduction in Alkaline Media
Authors: Levy Naomi , Mahammed Atif , Friedman Ariel , Gavriel Bar , Gross Zeev , Elbaz Lior 
Published: August 2016

AbstractA series of non‐precious metal complexes, composed of five first‐row transition‐metal complexes with β‐pyrrole‐brominated 5,10,15‐tris(pentafluorophenyl)corroles [M(tpfcBr8), M=Mn, Fe, Co, Ni, and Cu], was investigated as catalysts for oxygen reduction in an alkaline solution (0.1 m KOH). The corroles were adsorbed on a high surface area carbon powder (BP2000) prior to electrochemical measurements to create a unique composite material. The comparison between the different metal complexes revealed a high oxygen reduction reaction (ORR) catalytic performance in the case of the Fe‐ and Co‐corroles. These complexes reduce oxygen at very low overpotentials (with E1/2=0.79 V and 0.77 V vs. RHE, respectively), which is better than other well‐defined molecular catalysts and comparable to that of Pt on carbon (XC‐72). The mechanism by which the most active complexes catalyze the ORR in alkaline solutions was also studied, disclosing that the dominant reaction path is a four‐electron reduction of molecular oxygen to hydroxide.
Catalyst Decomposition during Olefin Metathesis Yields Isomerization‐Active Ruthenium Nanoparticles
Authors: Higman Carolyn S. , Lanterna Anabel E. , Marin M. Luisa , Scaiano Juan C. , Fogg Deryn E. 
Published: August 2016

AbstractThe front cover artwork for Issue 15/2016 is provided by the Fogg and Scaiano groups at the University of Ottawa (Canada). The image shows a well‐defined, homogeneous catalyst entering the active cycle for olefin metathesis, and exit of the decomposed catalyst in the form of ruthenium nanoparticles. See the Communication itself at http://dx.doi.org/10.1002/cctc.201600738.