bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple Multidentate Halogen Bonding in Solution, in the Solid State, and in the (Calculated) Gas Phase
Authors: Jungbauer Stefan H. , Schindler Severin , Herdtweck Eberhardt , Keller Sandro , Huber Stefan M. 
Published: August 2015

AbstractThe binding properties of neutral halogen‐bond donors (XB donors) bearing two multidentate Lewis acidic motifs toward halides were investigated. Employing polyfluorinated and polyiodinated terphenyl and quaterphenyl derivatives as anion receptors, we obtained X‐ray crystallographic data of the adducts of three structurally related XB donors with tetraalkylammonium chloride, bromide, and iodide. The stability of these XB complexes in solution was determined by isothermal titration calorimetry (ITC), and the results were compared to X‐ray analyses as well as to calculated binding patterns in the gas phase. Density functional theory (DFT) calculations on the gas‐phase complexes indicated that the experimentally observed distortion of the XB donors during multiple multidentate binding can be reproduced in 1:1 complexes with halides, whereas adducts with two halides show a symmetric binding pattern in the gas phase that is markedly different from the solid state structures. Overall, this study demonstrates the limitations in the transferability of binding data between solid state, solution, and gas phase in the study of complex multidentate XB donors.
Intramolecular Acylal Cyclisation (IAC) as an Efficient Synthetic Strategy towards the Total Synthesis of Erythrina Alkaloid Derivatives
Authors: Monaco Alessandra , Aliev Abil E. , Hilton Stephen T. 
Published: August 2015

AbstractCompounds that comprise the erythrina alkaloid class of natural products are based on a tetracyclic spiroamine framework and exhibit a range of biological activities on the central nervous system. Herein, we report a new and efficient total synthesis of this multiple‐ring system based on an intramolecular acylal cyclisation (IAC) approach. Using this methodology, the tetracyclic core was rapidly assembled over a two‐step domino process catalysed by a Lewis acid. The effect of heteroatoms, substituents and ring size on the IAC has also been investigated, and the broad application of this procedure is demonstrated by the synthesis of a library of derivatives in good yields with excellent regioselectivity.
Spontaneous Dimerization of Allenes in Situ: An Efficient Synthesis of Substituted 1,2‐Dimethylenecyclobutanes with High Regio‐ and Stereoselectivities
Authors: Miao Maozhong , Wang Wenmin , Yang Weijun , Xu Lijun , Ma Jing , Ren Hongjun 
Published: August 2015

AbstractAn intermolecular [2+2] cycloaddition reaction for the synthesis of 1,2‐dimethylenecyclobutane derivatives from the commercially available starting materials aryl acetylenes, nBuLi, formamides, and trimethylsilyl cyanide (TMSCN) has been achieved. This reaction displays high regio‐ and stereoselectivities due to the captodative effect. The mechanism of the reaction has been investigated by the deuterium labeling experiments and DFT calculations.
Palladium‐Catalyzed Oxidative Cycloisomerization of 2‐Cinnamyl‐1,3‐Dicarbonyls: Synthesis of Functionalized 2‐Benzyl Furans
Authors: Nallagonda Rajender , Reddy Reddy Rajasekhar , Ghorai Prasanta 
Published: August 2015

AbstractA new palladium‐catalyzed intramolecular oxidative cycloisomerization of readily available starting materials, 2‐cinnamyl‐1,3‐dicarbonyls, has been demonstrated for the creation of structurally diverse 2‐benzyl furans. The cycloisomerization occurs by a regioselective 5‐exo‐trig pathway. The reaction shows a broad substrate scope with good to excellent yields. Furthermore, a one‐pot procedure has been executed by using readily available cinnamyl alcohols and 1,3‐diketones.
Thermal‐Enzymatic Hydrolysis of Wheat Straw in a Single High Pressure Fixed Bed
Authors: Reynolds Wienke , Kirsch Christian , Smirnova Irina 
Published: August 2015

AbstractAn integrated flow‐through fixed‐bed reactor concept for lignocellulose separation at 3 L scale is presented. Wheat straw is degraded using sequential liquid hot water treatment and enzymatic hydrolysis in a single‐pot reactor setup. System responses on process parameters are modeled and optimized using response surface methodology. Accurate empiric models and significant factor influences could be identified for both treatment steps. With optimal factor settings, 23.9 and 49.2 wt % hot‐water‐soluble lignin and C5 oligomers could be recovered, respectively. 70.0 wt % cellulose solubilization could be achieved in the fixed‐bed enzymatic hydrolysis after 72 hours.
Partikelform und Porosität von biogenen Pyrolysekoksen
Authors: Nicoleit Thomas , Haßel Arndt , Niebel Andreas , Sauer Jörg 
Published: August 2015

AbstractKokspartikel aus pyrolysierter Biomasse variieren stark in Partikelgröße und ‐form. Die durchschnittliche Länglichkeit der Partikel nimmt mit der Größe signifikant zu. In Abhängigkeit der Partikelgröße ist die durchschnittliche Länglichkeit für die untersuchten Proben unabhängig von Ausgangsstoff und Pyrolyseverfahren. Mit klassischen kugelbasierten Größenverteilungen werden die Partikel nur ungenau beschrieben. Unter Berücksichtigung der Partikelform lassen sich die Kokse mittels Partikelgrößenverteilungen beschreiben, die auf einem Ellipsoidmodell basieren. Die hohe Schüttgutporosität ist im Wesentlichen auf die interpartikulären Zwischenräume zurückzuführen.
Synthesis of Hydroxyapatite Nanorods under Mild Conditions and Their Drug Release Properties
Authors: Kong Deyan , Xiao Xinli , Qiu Xueying , Zhang Wenbo , Yang Yulin 
Published: August 2015

AbstractHydroxyapatite (HAp) nanorods possess vast potential applications in various fields, and here HAp nanorods with high aspect ratio were synthesized via a convenient two‐stage precipitation‐hydrolysis process at 60°C under atmospheric pressure. The precursor of CaHPO4 at precipitation stage is well crystallized as nubby morphology with CTAB as surfactant, while CaHPO4 was dissolved and CTA+ stabilized the HAp nuclei during the hydrolysis stage. OH− ions were absorbed onto the active crystal surface, where Ca2+ and PO43+ reacted with OH− to make the nuclei grow into larger crystals, and highly crystalline HAp nanorods were obtained by Ostwald ripening. The loaded drug of IBU on the HAp crystals can be 100% released in 24 h. PVP modified HAp nanorods can increase the drug‐loading capacity and release drug faster than pure HAp nanorods. The results indicate that HAp nanorods modified with suitable surfactants are of great use in drug delivery system.
Well‐Posed Treatment of Space‐Charge Layers in the Electroneutral Limit of Electrodiffusion
Authors: Stinchcombe Adam R. , Mori Yoichiro , Peskin Charles S. 
Published: August 2015

AbstractThe electroneutral model describes cellular electrical activity, accounting for ionic concentration dynamics without resolution of the fine spatial scales of the space‐charge layer. This is done by asserting that the ionic solution is electrically neutral at each point in space. However, electroneutrality is inconsistent with the original boundary conditions at cell membranes. We consider three separate methods of resolving this inconsistency that result in well‐posed models that are accurate approximations to a detailed model in which the space‐charge layer is fully resolved. A particular electrodiffusion problem is utilized to make the discussion specific.© 2015 Wiley Periodicals, Inc.
Highly Active and Durable Nanocrystal‐Decorated Bifunctional Electrocatalyst for Rechargeable Zinc–Air Batteries
Authors: Lee Dong Un , Park Moon Gyu , Park Hey Woong , Seo Min Ho , Wang Xiaolei , Chen Zhongwei 
Published: August 2015

AbstractA highly active and durable bifunctional electrocatalyst that consists of cobalt oxide nanocrystals (Co3O4 NC) decorated on the surface of N‐doped carbon nanotubes (N‐CNT) is introduced as effective electrode material for electrically rechargeable zinc–air batteries. This active hybrid catalyst is synthesized by a facile surfactant‐assisted method to produce Co3O4 NC that are then decorated on the surface of N‐CNT through hydrophobic attraction. Confirmed by half‐cell testing, Co3O4 NC/N‐CNT demonstrates superior oxygen reduction and oxygen evolution catalytic activities and has a superior electrochemical stability compared to Pt/C and Ir/C. Furthermore, rechargeable zinc–air battery testing of Co3O4 NC/N‐CNT reveals superior galvanodynamic charge and discharge voltages with a significantly extended cycle life of over 100 h, which suggests its potential as a replacement for precious‐metal‐based catalysts for electric vehicles and grid energy storage applications.
Deuterium‐Labeling Study of the Hydrogenation of 2‐Methylfuran and 2,5‐Dimethylfuran over Carbon‐Supported Noble Metal Catalysts
Authors: Kang Jungshik , Vonderheide Anne , Guliants Vadim V. 
Published: August 2015

Abstract2‐Methylfuran and 2,5‐dimethylfuran were deuterated over Pd and Pt catalysts at 90–220 °C. Furan ring saturation over a Pd/C catalyst occurred at low reaction temperatures, which led to deuterated THFs, followed by progressive D exchange in the THF ring at higher temperatures. Finally, H/D exchange occurred in the methyl groups on the THF ring. Cleavage of the CO bond also occurred over a Pd/C catalyst at elevated temperatures, which resulted in deuterated ketones, for which all H atoms were exchanged for D. Alcohols were produced over a Pt/C catalyst at low temperatures because they are more stable than the corresponding ketones. D replaced H on all carbon atoms of the furan ring and saturated the O and C atoms of the broken CO bond in both deuterated 2‐pentanol and 2‐hexanol. At low temperatures (90–105 °C), all H atoms in the deuterated alcohols were exchanged for D except for the last two hydrogen atoms on the methyl groups.
Prevalence and management of oropharyngeal dysphagia in patients with severe anorexia nervosa: A large retrospective review
Authors: Holmes Samantha R.M. , Sabel Allison L. , Gaudiani Jennifer L. , Gudridge Tricia , Brinton John T. , Mehler Philip S. 
Published: August 2015

ABSTRACTObjectiveOropharyngeal dysphagia (OPD) refers to difficulty swallowing food or a liquid bolus from the oral and pharyngeal cavities into the esophagus and increases the risk of possibly life‐threatening pneumonia. Little has been reported on OPD in adults with anorexia nervosa (AN). This study includes a description of OPD in severe AN and discusses potentially effective clinical management.MethodTwo hundred and six adults with severe AN, admitted over a five‐year period to a national referral center specializing in the multidisciplinary medical stabilization of this population, were retrospectively evaluated by electronic database query and manual chart review. All patients whose initial medical assessment triggered a speech‐language pathology (SLP) consultation, due to concerns for OPD, were reviewed in detail.ResultsOf the 206 total patients, 42 presented with symptoms of OPD and received SLP consultation. In the OPD cohort, 37 (88%) were women, with median age 32 years old, and mean admission weights of 57% ideal body weight (IBW) and body mass index (BMI) of 12 kg/m2. Compared with those who did not have OPD, OPD patients had significantly lower BMI on admission (12 kg/m2 vs. 13.1 kg/m2, p < 0.001), longer stay (21 days vs. 14 days, p < 0.001), and were more medically compromised, including a greater incidence of refeeding hypophosphatemia (60.9% vs. 29.7%, p < 0.004).DiscussionClinical awareness of OPD may reduce the incidence of aspiration pneumonia and promote life‐saving oral nutrition in patients with severe AN. Proper, timely evaluation and intervention may improve clinical outcomes. © 2015 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:159–166).
A Pyrazolate‐Bridged Bis(pentadentate) Ligand and Its Dinuclear Ruthenium Complex
Authors: Sander Anett C. , Schober Anne , Dechert Sebastian , Meyer Franc 
Published: August 2015

AbstractA new bis(pentadentate) pyrazole‐bridged proligand HLbis5 providing two {N5} binding pockets and its diruthenium complex [Lbis5Ru2(MeCN)2](PF6)3 (1) have been synthesized, and the structure of 1 has been elucidated by X‐ray diffraction. The two exogenous MeCN ligands in 1 are both directed into the central pocket created by the two metal ion compartments and interfere with each other, which leads to some distortion of the dimetallic framework. According to an Eyring analysis of variable‐temperature NMR spectroscopic data, interconversion of the resulting enantiomeric forms is rapid with a free activation energy of ΔG≠ = 43.7 kJ mol–1 at 298 K (ΔH≠ = 30.8 kJ mol–1, ΔS≠ = –43.2 J mol–1 K–1). Cyclic voltammetry of 1 shows two sequential reversible oxidations at ca. 0.85 and 1.25 V (vs. SCE), and the mixed‐valent RuIIIRuII species has been characterized by spectroelectrochemistry, UV/Vis/NIR and EPR spectroscopy. Complex 1 was found to be a poor catalyst for water oxidation: under standard conditions [triflic acid, pH 1, using cerium(IV) ammonium nitrate as oxidant] rapid degradation by oxidative ligand fragmentation at its benzylic‐type CH2 groups was observed.
Luminescence and Relaxometric Properties of Heteropolymetallic Metallostar Complexes with Selectively Incorporated Lanthanide(III) Ions
Authors: Ceulemans Matthias , Debroye Elke , Vander Elst Luce , De Borggraeve Wim , Parac‐Vogt Tatjana N. 
Published: August 2015

AbstractThe synthesis and characterization of two diethylenetriaminepentaacetic acid (DTPA) based heteropolymetallic metallostar lanthanide complexes with the general formulas (GdL1)3Ln and (GdL2)3Ln are described. The synthesis uses a synthetic approach recently developed in our group for the selective complexation of gadolinium(III) and luminescent lanthanide ions with a ditopic ligand to form highly paramagnetic and luminescent metallostar complexes. The luminescence data and relaxometric studies suggest the potential applicability of the complexes as bimodal contrast agents for magnetic resonance and optical imaging. Owing to the higher excited state of L1, better sensitization was observed for all (GdL1)3Ln complexes than for (GdL2)3Ln. A large increase of the quantum yield from 1.5 to 9.8 % was observed for the (GdL1)3Eu complex compared with (GdL2)3Eu, whereas the (GdL1)3Tb complex exhibited a quantum yield (QY) of 30.9 % compared with 15.3 % for (GdL2)3Tb. A slight increase of the QY from 0.8 to 1.2 % was observed for the Dy(III) complex when switching from ligand L2 to L1. The nuclear magnetic relaxation dispersion (NMRD) measurements of the (GdL2)3Ln complexes (Ln = EuIII, DyIII, TbIII) showed respective longitudinal relaxivity (r1) values of 24.27, 22.80 and 21.72 s–1 mmol–1 per metallostar complex at 310 K and 20 MHz.
Synergistic and Antagonistic Ligand Effects in the Transformation of Silver Compounds of Keto‐ and Cyano‐Functionalised Oximates and Nitronates: A Systematic Study Using Thermal Analysis
Authors: Hoffmann Rudolf C. , Schneider Jörg J. 
Published: August 2015

AbstractMolecular silver compounds are target precursor molecules for the deposition of silver films from solution. The thermal decomposition of silver complexes of nitro and nitroso derivatives of malononitrile, cyanoacetamide and methyl cyanoacetate as well as with nitroacetamide and methyl nitroacetate was investigated for the first time in a systematic manner. The analysis of the evolving gases by means of infrared spectroscopy or mass spectrometry revealed that intramolecular redox reactions had a significant impact on the reaction mechanism, in particular the interactions of the nitro and nitroso functionalities with amido and ester groups. The studied ligands bearing cyano groups typically lead to the intermediary formation of silver cyanide, whereby metallic silver is formed only at higher temperatures. Silver complexes of nitroacetamide and methyl nitroacetate, however, undergo decomposition to metallic silver at temperatures already below 200 °C. Thin films of silver on glass substrates could be synthesised by spincoating of these precursors and subsequent annealing. Higher conversion temperatures lead to more uniform surface coverage and lower film roughness.
A Cholesterol Containing pH‐Sensitive Bistable [2]Rotaxane
Authors: Berg Martin , Nozinovic Senada , Engeser Marianne , Lützen Arne 
Published: August 2015

AbstractA non‐symmetrical pH‐sensitive bistable [2]rotaxane that bears a cholesterol unit and a tetraphenylmethane group as stopper groups was designed and synthesized in 18 steps. The successful formation of the rotaxane was proven by NMR spectroscopy and MS/MS. Besides a permanent cationic alkylated triazolium unit, the axle contains a secondary amine that can act as a second pH‐sensitive binding site for a crown ether. Depending on the protonation state of this amine function, the crown ether reversibly changes its position by moving between the two binding sites along the axle, as revealed by NMR spectroscopy.
Visible‐Light‐Induced Meerwein Cascade Reactions for the Preparation of α‐Aryl Esters
Authors: Niu Teng‐fei , Li Liang , Ni Bang‐qing , Bu Mei‐jie , Cai Chun , Jiang Hui‐liang 
Published: August 2015

AbstractA practical strategy has been developed for preparation of α‐aryl ester derivatives by using a visible‐light‐induced Meerwein cascade reaction. This method uses molecular oxygen as an oxidant at room temperature without the need of hazardous reagents or harsh reaction conditions and provides a straightforward approach to pharmaceutically and synthetically useful α‐aryl esters in moderate to good yields from simple and readily available starting materials. Oxindoles were also prepared by this protocol.
An Air‐Stable Nickel(0) Phosphite Precatalyst for Primary Alkylamine C–N Cross‐Coupling Reactions
Authors: Kampmann Sven S. , Skelton Brian W. , Wild Duncan A. , Koutsantonis George A. , Stewart Scott G. 
Published: August 2015

AbstractIn this report we describe the design and preparation of a new air‐stable nickel phosphite based catalyst for unique C–N bond forming processes. Specifically, (BINAP)Ni[P(OPh)3]2, is presented as an effective catalyst for a range of amination reactions between aryl halides and primary alkylamines. The results are supported by relevant kinetic studies, DFT calculations and a catalytic cycle indicating possible reaction intermediates.
Theoretical Study, Synthesis, and Reactivity of Five‐Membered‐Ring Acyl Sulfonium Cations
Authors: Rao K. V. Raghavendra , Caiveau Nicolas , David Rolf , Shalayel Ibrahim , Milet Anne , Vallée Yannick 
Published: August 2015

AbstractThe feasibility of the cyclization of γ‐alkylthiobutyric acid derivatives to form previously unknown five‐membered‐ring acyl sulfonium cations was studied. Experimental results were in good agreement with our DFT calculations that predicted such cyclizations to be easy if starting with acyl iodides and mixed anhydrides of triflic acid. Particularly efficient were the reactions of γ‐alkylthiobutyryl fluorides with trimethylsilyl triflate in CDCl3 solution, which led to cyclic acyl sulfonium triflates. In some cases, the observed acyl sulfonium salts were stable enough to be characterized by NMR spectroscopy. They were found to be both alkyl‐transfer reagents and acylating agents. They react with amines to form amides. These findings lend some weight to our hypothesis that the acyl sulfonium derived from methionine may have played a major role in the prebiotic synthesis of the first peptides on the primitive Earth.
Synthesis of Silodosin by Copper‐Catalysed C–C Arylation
Authors: Calogero Francesco , Allegrini Pietro , Attolino Emanuele , Passarella Daniele 
Published: August 2015

AbstractThe synthesis of silodosin, an antidysuria drug, has been accomplished starting from commercially available indoline. The synthetic strategy is based on CuI‐catalysed C–C arylation, regioselective cyanation, and diastereoselective reductive amination. The enantiopure compound was obtained by selective crystallisation of a diasteroisomeric mixture.
Palladium‐Catalyzed 6‐endo‐Selective Oxycyclization–Alkene Addition Cascades of ortho‐Alkynylarylcarboxamides and α,β‐Unsaturated Carbonyl Compounds
Authors: Madich Youssef , Álvarez Rosana , Aurrecoechea José M. 
Published: August 2015

AbstractRegio‐ and chemoselective palladium‐catalyzed cyclization–coupling cascade reactions between ortho‐alkynylarylcarboxamides and methyl vinyl ketone or acrylaldehyde are described. An initial 6‐endo‐oxypalladation of the triple bond is followed by a C–C coupling to give structurally diverse isochromenimines (and related heterosubstituted derivatives), in which the α,β‐unsaturated carbonyl moiety is incorporated as an alkyl‐type exocyclic side chain. The coupling products were obtained in 76–97 % yield (average 86 % yield) without significant interference from Heck or alternative regiochemical pathways. In contrast to related cases, these cascade reactions do not require the use of protic solvents and excess amounts of halide additives, and they proceed effectively under either PdCl2 catalysis in the presence of substoichiometric amounts of added KI or PdI2 catalysis without any additive.
Hydrogenation of Aliphatic and Aromatic Nitriles Using a Defined Ruthenium PNP Pincer Catalyst
Authors: Neumann Jacob , Bornschein Christoph , Jiao Haijun , Junge Kathrin , Beller Matthias 
Published: August 2015

AbstractSelective catalytic reductions of nitriles are presented using the commercially available Ru‐Macho‐BH complex. A variety of aliphatic, aromatic and (hetero)cyclic nitriles including industrially important adipodinitrile are hydrogenated to the corresponding primary amines. Modelling suggests the reaction follows an outer sphere hydrogenation mechanism.
A Facile Graphene Nanosheets‐based Electrochemical Sensor for Sensitive Detection of Honokiol in Traditional Chinese Medicine
Authors: Zhang Yang , Zhang Meiqin , Zhu Yu , Wei Qianhui , Li Xiaolong , Ou Yunyun , Ao Ning , Zhang Xueji 
Published: August 2015

AbstractThe sensitive detection of honokiol was performed using a graphene nanosheets‐based electrochemical sensor by cyclic voltammogram and a differential pulse anodic stripping voltammogram. Several important parameters such as deposition cycle of reduced graphene oxide, the acidity of the running buffer, accumulation potential and accumulation time were investigated to acquire the optimum conditions. The sensor was further applied to quantification of honokiol in the concentration range from 0.005 to 10 µM with a low detection limit of 1.7 nM. Finally, the sensor successfully determined the content of honokiol in Ageratum Liquid with a satisfied recovery of 98.2 %∼99.1 %.
Modification of the Electrode Surface by Ag Nanoparticles Decorated Nano Diamond‐graphite for Voltammetric Determination of Ceftizoxime
Authors: Shahrokhian Saeed , Ranjbar Saba , Ghalkhani Masoumeh 
Published: August 2015

AbstractA modified glassy carbon electrode with a film of nano diamondgraphite nano mixture decorated with Ag nanoparticles (AgNPsNDG/GCE) was constructed and used for sensitive voltammetric determination of ceftizoxime (CFX). Morphology of AgNPsNDG/GCE has been examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Experimental variables such as deposited amount of the modifier suspension, pH of the supporting electrolyte and accumulation potential and time were optimized by monitoring of CV and LSV responses of CFX. The results illustrate that AgNPsNDG/GCE exhibits an excellent electrocatalytic effect in the electro‐oxidation of CFX that leads to a considerable improvement in the corresponding anodic peak current. This also allows the development of a highly sensitive voltammetric sensor for the determination of CFX in pharmaceutical and clinical samples. Under the optimum conditions, the modified electrode showed a linear response to the concentration of CFX in the range of 0.02–7 µM with detection limit of 6 nM. The prepared modified electrode has some remarkable electrochemical properties such as simple preparation, high sensitivity, excellent repeatability and reproducibility and long‐term stability.