bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorescent Probes of the Apoptolidins and their Utility in Cellular Localization Studies
Authors: DeGuire Sean M. , Earl David C. , Du Yu , Crews Brenda A. , Jacobs Aaron T. , Ustione Alessandro , Daniel Cristina , Chong Katherine M. , Marnett Lawrence J. , Piston David W. , Bachmann Brian O. , Sulikowski Gary A. 
Published: November 2014

AbstractApoptolidin A has been described among the top 0.1 % most‐cell‐selective cytotoxic agents to be evaluated in the NCI 60 cell line panel. The molecular structure of apoptolidin A consists of a 20‐membered macrolide with mono‐ and disaccharide moieties. In contrast to apoptolidin A, the aglycone (apoptolidinone) shows no cytotoxicity (>10 μM) when evaluated against several tumor cell lines. Apoptolidin H, the C27 deglycosylated analogue of apoptolidin A, displayed sub‐micromolar activity against H292 lung carcinoma cells. Selective esterification of apoptolidins A and H with 5‐azidopentanoic acid afforded azido‐functionalized derivatives of potency equal to that of the parent macrolide. They also underwent strain‐promoted alkyne–azido cycloaddition reactions to provide access to fluorescent and biotin‐functionalized probes. Microscopy studies demonstrate apoptolidins A and H localize in the mitochondria of H292 human lung carcinoma cells.
Aufklärung der Solvatationsdynamik eines einzelnen Wassermoleküls durch Infrarotspektroskopie: Theorie und Experiment
Authors: Wohlgemuth Matthias , Miyazaki Mitsuhiko , Weiler Martin , Sakai Makoto , Dopfer Otto , Fujii Masaaki , Mitrić Roland 
Published: November 2014

AbstractDie Dynamik und Energetik von Wasser an Grenzflächen oder in biologischen Systemen spielt eine grundlegende Rolle bei allen Solvatations‐ und biologischen Phänomenen in wässrigen Lösungen. Insbesondere ist die Migration von Wassermolekülen der erste Schritt, der den Gesamtprozess in zeitlicher Hinsicht steuert. Es ist jedoch fast unmöglich, im Experiment die Dynamik individueller Wassermoleküle in der Lösung zu verfolgen, da sich die Signale der Moleküle in heterogenen Umgebungen überlagern. Auch wenn für Simulationen der Molekulardynamik diese Einschränkung nicht gilt, fehlt es an experimentellen Daten, um die berechnete Dynamik zu validieren. Im Folgenden zeigen wir eine neue Strategie auf, mithilfe derer die berechnete Dynamik durch die Messung zeitaufgelöster Infrarotspektren verifiziert wird. Die Koexistenz von schneller und langsamer Wassermolekül‐Migration um eine CONH‐Peptid‐Bindung wird anhand eines Modellsystems gezeigt, das einen Teil eines hydratisierten Peptids repräsentiert.
Metal‐Atom Impact on the Self‐Assembly of Cup‐and‐Ball Metalloporphyrin–Fullerene Conjugates
Authors: Moreira Luis , Calbo Joaquín , Illescas Beatriz M. , Aragó Juan , Nierengarten Iwona , Delavaux‐Nicot Béatrice , Ortí Enrique , Martín Nazario , Nierengarten Jean‐François 
Published: November 2014

AbstractA fullerene ammonium derivative has been combined with different metalloporphyrin–crown ether receptors to generate very stable supramolecules. The combination of fullerene–porphyrin and ammonium–crown ether interactions leads to a strong chelate effect as evidenced by a high effective molarity (3.16 M). The different parameters influencing the stability of the supramolecular ensembles, in particular the nature of the metal in the porphyrin moiety, have been rationalized with the help of theoretical calculations thus providing new insights into fullerene–porphyrin interactions.
Hydrolysis of a Lipid Membrane by Single Enzyme Molecules: Accurate Determination of Kinetic Parameters
Authors: Rabe Michael , Tabaei Seyed R. , Zetterberg Henrik , Zhdanov Vladimir P. , Höök Fredrik 
Published: November 2014

AbstractThe accurate determination of the maximum turnover number and Michaelis constant for membrane enzymes remains challenging. Here, this problem has been solved by observing in parallel the hydrolysis of thousands of individual fluorescently labeled immobilized liposomes each processed by a single phospholipase A2 molecule. The release of the reaction product was tracked using total internal reflection fluorescence microscopy. A statistical analysis of the hydrolysis kinetics was shown to provide the Michaelis–Menten parameters with an accuracy better than 20 % without variation of the initial substrate concentration. The combined single‐liposome and single‐enzyme mode of operation made it also possible to unravel a significant nanoscale dependence of these parameters on membrane curvature.
The Isothiocyanato Moiety: An Ideal Protecting Group for the Stereoselective Synthesis of Sialic Acid Glycosides and Subsequent Diversification
Authors: Mandhapati Appi Reddy , Rajender Salla , Shaw Jonathan , Crich David 
Published: November 2014

AbstractThe preparation of a crystalline, peracetyl adamantanyl thiosialoside donor protected by an isothiocyanate group is described. On activation at −78 °C in the presence of typical carbohydrate acceptors, this donor gives high yields of the corresponding sialosides with exquisite α‐selectivity. The high selectivity extends to the 4‐O‐benzyl‐protected 3‐OH acceptors, which are typically less reactive and selective than galactose 3,4‐diols. Treatment of the α‐sialosides with tris(trimethylsilyl)silane or allyltris(trimethylsilyl)silane results in replacement of the C5N5 bond by a CH or a CC bond. The reaction of the isothiocyanate‐protected sialosides with thioacids generates amides, while reaction with an amine gives a thiourea, which can be converted into a guanidine. The very high α‐selectivities observed with the new donor and the rich chemistry of the isothiocyante function considerably extend the scope for optimization at the sialoside 5‐position.
An Alkyne‐Appended, Click‐Ready PtII Complex with an Unusual Arrangement in the Solid State
Authors: White Jonathan D. , Guzman Lindsay E. , Zakharov Lev N. , Haley Michael M. , DeRose Victoria J. 
Published: November 2014

AbstractTo better understand the range of cellular interactions of PtII‐based chemotherapeutics, robust and efficient methods to track and analyze Pt targets are needed. A powerful approach is to functionalize PtII compounds with alkyne or azide moieties for post‐treatment conjugation through the azide–alkyne cycloaddition (click) reaction. Herein, we report an alkyne‐appended cis‐diamine PtII compound, cis‐[Pt(2‐(5‐hexynyl)amido‐1,3‐propanediamine)Cl2] (1), the X‐ray crystal structure of which exhibits a combination of unusual radially distributed CH/π(CC) interactions, PtPt bonding, and NH:O/NH:Cl hydrogen bonds. In solution, 1 exhibits no Ptalkyne interactions and binds readily to DNA. Subsequent click reactivity with nonfluorescent dansyl azide results in a 70‐fold fluorescence increase. This result demonstrates the potential for this new class of alkyne‐modified Pt compound for the comprehensive detection and isolation of Pt‐bound biomolecules.
Intermolecular Dynamic Kinetic Resolution Cooperatively Catalyzed by an N‐Heterocyclic Carbene and a Lewis Acid
Authors: Wu Zijun , Li Fangyi , Wang Jian 
Published: November 2014

AbstractThe ubiquitous structure of δ‐lactones makes the development of new methods for their enantioselective and stereoselective synthesis an important ongoing challenge. The intermolecular dynamic kinetic resolution (DKR) of β‐halo‐α‐ketoesters cooperatively catalyzed by an N‐heterocyclic carbene and a Lewis acid generates two contiguous stereocenters with remarkable diastereoselectivity through an oxidation/lactonization sequence.
Tuning the Reactivity of Isocyano Group: Synthesis of Imidazoles and Imidazoliums from Propargylamines and Isonitriles in the Presence of Multiple Catalysts
Authors: Tong Shuo , Wang Qian , Wang Mei‐Xiang , Zhu Jieping 
Published: November 2014

AbstractThe reaction of propargyl amines with tert‐butylisonitrile in the presence of a catalytic amount of both Yb(OTf)3 and AgOTf afforded imidazoles, whereas the same reaction with primary and secondary alkylisonitriles, as well as arylisonitriles, in the presence of three metal salts [Yb(OTf)3/AgOTf/KOTf] resulted in the 1,3,4,5‐tetrasubstituted imidazoliums in excellent yields. Both chiral amines and chiral isonitriles can be used to provide corresponding chiral heterocycles without racemization. In this multiple catalytic system, Yb(OTf)3 catalyzed the insertion of isonitriles to the NH bond of amines, AgOTf catalyzed the 5‐exo‐dig cyclization of the resulting amidine nitrogen to the tethered triple bond, and KOTf promoted the salt metathesis, thus providing at the same time the counterion to the imidazolium. Against common knowledge, the isocyano group acted in these reactions as a polarized triple bond instead of conventional carbene‐like function.
Switchable Guest Molecular Dynamics in a Perovskite‐Like Coordination Polymer toward Sensitive Thermoresponsive Dielectric Materials
Authors: Du Zi‐Yi , Xu Ting‐Ting , Huang Bo , Su Yu‐Jun , Xue Wei , He Chun‐Ting , Zhang Wei‐Xiong , Chen Xiao‐Ming 
Published: November 2014

AbstractA new perovskite‐like coordination polymer [(CH3)2NH2][Cd(N3)3] is reported which undergoes a reversible ferroelastic phase transition. This transition is due to varied modes of motion of the [(CH3)2NH2]+ guest accompanied by a synergistic deformation of the [Cd(N3)3]− framework. The unusual two‐staged switchable dielectric relaxation reveals the molecular dynamics of the polar cation guest, which are well controlled by the variable confined space of the host framework. As the material switches from the ferroelastic phase to the paraelastic phase, a remarkable increase of the rotational energy barrier is detected. As a result, upon heating at low temperature, this compound shows a notable change from a low to a high dielectric state in the ferroelastic phase. This thermoresponsive host–guest system may serve as a model compound for the development of sensitive thermoresponsive dielectric materials and may be key to understanding and modulating molecular/ionic dynamics of guest molecules in confined space.
Thiol–Ene “Click” Reaction Triggered by Neutral Ionic Liquid: The “Ambiphilic” Character of [hmim]Br in the Regioselective Nucleophilic Hydrothiolation
Authors: Kumar Rajesh , Saima  , Shard Amit , Andhare Nitin H. , Richa  , Sinha Arun K. 
Published: November 2014

AbstractThiol–ene “click” chemistry has emerged as a powerful strategy to construct carbon–heteroatom (CS) bonds, which generally results in the formation of two regioisomers. To this end, the neutral ionic liquid [hmim]Br has been explored as a solvent cum catalyst for the synthesis of linear thioethers from activated and inactivated styrene derivatives or secondary benzyl alcohols and thiols without the requirement of using a metal complex, base, or free radical initiator. Furthermore, detailed mechanistic investigations using 1H NMR spectroscopy and quadrupole time‐of‐flight electrospray ionization mass spectrometry (Q‐TOF ESI‐MS) revealed that the “ambiphilic” character of the ionic liquid promotes the nucleophilic addition of thiol to styrene through an anti‐Markovnikov pathway. The catalyst recyclability and the extension of the methodology for thiol–yne click chemistry are additional benefits. A competitive study among thiophenol, styrene, and phenyl acetylene revealed that the rate of reaction is in the order of thiol–yne>thiol–ene>dimerization of thiol in [hmim]Br.
An Allosteric Receptor by Simultaneous “Casting” and “Molding” in a Dynamic Combinatorial Library
Authors: Li Jianwei , Nowak Piotr , Otto Sijbren 
Published: November 2014

AbstractAllosteric synthetic receptors are difficult to access by design. Herein we report a dynamic combinatorial strategy towards such systems based on the simultaneous use of two different templates. Through a process of simultaneous casting (the assembly of a library member around a template) and molding (the assembly of a library member inside the binding pocket of a template), a Russian‐doll‐like termolecular complex was obtained with remarkable selectivity. Analysis of the stepwise formation of the complex indicates that binding of the two partners by the central macrocycle exhibits significant positive cooperativity. Such allosteric systems represent hubs that may have considerable potential in systems chemistry.
Molecular Chirality in Meteorites and Interstellar Ices, and the Chirality Experiment on Board the ESA Cometary Rosetta Mission
Authors: Myrgorodska Iuliia , Meinert Cornelia , Martins Zita , Le Sergeant d'Hendecourt Louis , Meierhenrich Uwe J. 
Published: November 2014

AbstractLife, as it is known to us, uses exclusively L‐amino acid and D‐sugar enantiomers for the molecular architecture of proteins and nucleic acids. This Minireview explores current models of the original symmetry‐breaking influence that led to the exogenic delivery to Earth of prebiotic molecules with a slight enantiomeric excess. We provide a short overview of enantiomeric enhancements detected in bodies of extraterrestrial origin, such as meteorites, and interstellar ices simulated in the laboratory. Data are interpreted from different points of view, namely, photochirogenesis, parity violation in the weak nuclear interaction, and enantioenrichment through phase transitions. Photochemically induced enantiomeric imbalances are discussed more specifically in the topical context of the “chirality module” on board the cometary Rosetta spacecraft of the ESA. This device will perform the first enantioselective in situ analyses of samples taken from a cometary nucleus.
Phase Behavior of a Designed Cyclopropyl Analogue of Monoolein: Implications for Low‐Temperature Membrane Protein Crystallization
Authors: Salvati Manni Livia , Zabara Alexandru , Osornio Yazmin M. , Schöppe Jendrik , Batyuk Alexander , Plückthun Andreas , Siegel Jay S. , Mezzenga Raffaele , Landau Ehud M. 
Published: November 2014

AbstractLipidic cubic phases (LCPs) are used in areas ranging from membrane biology to biodevices. Because some membrane proteins are notoriously unstable at room temperature, and available LCPs undergo transformation to lamellar phases at low temperatures, development of stable low‐temperature LCPs for biophysical studies of membrane proteins is called for. Monodihydrosterculin (MDS) is a designer lipid based on monoolein (MO) with a configurationally restricted cyclopropyl ring replacing the olefin. Small‐angle X‐ray scattering (SAXS) analyses revealed a phase diagram for MDS lacking the high‐temperature, highly curved reverse hexagonal phase typical for MO, and extending the cubic phase boundary to lower temperature, thereby establishing the relationship between lipid molecular structure and mesophase behavior. The use of MDS as a new material for LCP‐based membrane protein crystallization at low temperature was demonstrated by crystallizing bacteriorhodopsin at 20 °C as well as 4 °C.
An Alternative Mechanism for the Cobalt‐Catalyzed Isomerization of Terminal Alkenes to (Z)‐2‐Alkenes
Authors: Schmidt Anastasia , Nödling Alexander R. , Hilt Gerhard 
Published: November 2014

AbstractThe cobalt‐catalyzed selective isomerization of terminal alkenes to the thermodynamically less‐stable (Z)‐2‐alkenes at ambient temperatures takes place by a new mechanism involving the transfer of a hydrogen atom from a Ph2PH ligand to the starting material and the formation of a phosphenium complex, which recycles the Ph2PH complex through a 1,2‐H shift.
Access to Novel Graphene‐Like Sheet of Hydroboron: First‐Principles Investigation
Authors: Wu Yang‐Yang , Zhao Feng‐Qi , Xu Si‐Yu , Ju Xue‐Hai 
Published: November 2014

AbstractWe designed a cyclic borane (B6H12) molecule with a benzene‐like structure, in which the six B atoms are located in the same plane. Three methods of B3LYP, MP2, and CCSD with the 6‐311++G** basis were used to investigate its structure, electronic property, and stability. Next, we calculated the stability and electronic property of three hydroboron derivatives with fused rings of B10H18, B14H24, and B16H26. Finally, we investigated three types of novel two‐dimensional infinite hydroboron sheets with diborane as a building block. The results of the phonon spectra ensure the dynamic stability of these predicted structures. Furthermore, the three types of hydroboron sheets are shown to have different band gap energies of less than 3.0 eV. Some investigations on the optical properties have also been performed. The predicted sheets are candidates for semiconductors, whose band gap energy can be tuned by the positions of the bridge hydrogen atoms in the sheets.
A case of myositis of the deltoid muscle of the upper arm developing 1 week after influenza vaccination: case report
Authors: Urayoshi Shunsuke , Matsumoto Satohiro , Miyatani Hiroyuki , Yoshida Yukio 
Published: November 2014

Key Clinical MessageWe report a case of an elderly man who developed myositis of the deltoid muscle 8 days after influenza vaccination. Adverse reactions to influenza vaccine are generally immediate reactions. However, delayed‐type hypersensitivity reactions, although rare, can occur after routine influenza vaccination.
Submerged Membrane Bioreactor for Vegetable Oil Wastewater Treatment
Authors: Ma Zhun , Lei Ting , Ji Xiaosheng , Gao Xueli , Gao Congjie 
Published: November 2014

AbstractA bench‐scale submerged membrane bioreactor (SMBR) was employed to treat vegetable oil plant wastewater with complete sludge retention. Treatment performance and membrane fouling of the SMBR were investigated. The system stably removed high amounts of total organic carbon, oil, and ammonia from vegetable oil wastewater and reduced the chemical oxygen demand, demonstrating the great potential of the SMBR in removing pollutants. The membrane fouling layer was not only governed by deposition of organic substances composed of extracellular polymeric substances like proteins, polysaccharides etc., and oil substances but also by inorganic elements. Organic foulants coupled to inorganic precipitation enhanced the formation of a gel layer and triggered severe membrane fouling in the SMBR.
Predicting Power for a Scaled‐up Non‐Newtonian Biomass Slurry
Authors: Russ David C. , Thomas Jonathan M. D. , Miller Q. Sean , Berson R. Eric 
Published: November 2014

AbstractHigh‐solids biomass slurries exhibit non‐Newtonian behavior with a yield stress and require high power input for mixing. The goals were to determine the effect of scale and geometry on power number P0, and estimate the power for mixing a pretreated biomass slurry in a 3.8 million L hydrolysis reactor of conventional design. A lab‐scale computational fluid dynamics model was validated against experimental data and then scaled up. A pitched‐blade turbine and A310 hydrofoil were tested for various geometric arrangements. Flow was transitional; laminar and turbulence models resulted in equivalent P0 which increased with scale. The ratio of impeller diameter to tank diameter affected P0 for both impellers, but impeller clearance to tank diameter affected P0 only for the A310. At least 2 MW is required to operate at this scale.
Environmentally Friendly Solvent‐ and Water‐Based Coatings for Mitigation of Crystallization Fouling
Authors: Al‐Janabi Abdullah , Malayeri M. Reza 
Published: November 2014

AbstractThe surface properties of solvent‐based (SB) and water‐based (WB) coatings and their impact on fouling during convective heat transfer of CaSO4 solutions were investigated. Experiments demonstrated that the SB coatings had generally better non‐adhesive characteristics, especially at higher values of the electron donor component since the deposits could easily be washed away. For the SB coatings, a longer induction period compared to those of untreated surfaces was observed and a significant reduction of the fouling rate could be achieved. Further analysis of surfaces revealed that SB coatings enhanced the acid‐base repulsive force and thus reduced the deposit/solid adhesion energy. For the WB coatings, the Liftshitz‐van der Waals attractive force plays a decisive role in the adhesion process due to the higher apolar component of the surface energy.
Electrically Switchable Magnetic Molecules: Inducing a Magnetic Coupling by Means of an External Electric Field in a Mixed‐Valence Polyoxovanadate Cluster
Authors: Cardona‐Serra Salvador , Clemente‐Juan Juan M. , Coronado Eugenio , Gaita‐Ariño Alejandro , Suaud Nicolas , Svoboda Ondrej , Bastardis Roland , Guihéry Nathalie , Palacios Juan J. 
Published: November 2014

AbstractHerein we evaluate the influence of an electric field on the coupling of two delocalized electrons in the mixed‐valence polyoxometalate (POM) [GeV14O40]8− (in short V14) by using both a t‐J model Hamiltonian and DFT calculations. In absence of an electric field the compound is paramagnetic, because the two electrons are localized on different parts of the POM. When an electric field is applied, an abrupt change of the magnetic coupling between the two delocalized electrons can be induced. Indeed, the field forces the two electrons to localize on nearest‐neighbors metal centers, leading to a very strong antiferromagnetic coupling. Both theoretical approaches have led to similar results, emphasizing that the sharp spin transition induced by the electric field in the V14 system is a robust phenomenon, intramolecular in nature, and barely influenced by small changes on the external structure.
Turn‐On Fluorescence and Unprecedented Encapsulation of Large Aromatic Molecules within a Manganese(II)–Triazole Metal–Organic Confined Space
Authors: Wang Ying , Yuan Bin , Xu Yao‐Yao , Wang Xiu‐Guang , Ding Bin , Zhao Xiao‐Jun 
Published: November 2014

AbstractFor the purpose of investigating the coordination behavior of sterically congested alkenes and exploring the possibility of cofacial complexation in the polycyclic aromatic system for the formation of extended polymeric networks, a new tetradentate ligand, 1,1,2,2‐tetrakis[4‐(1H‐1,2,4‐triazol‐1‐yl)phenyl]ethylene (TTPE), has been designed and synthesized. By using TTPE as a building block with regard to the self‐assembly with MnCl2⋅4 H2O, a novel two‐dimensional coordination framework {[Mn(TTPE)Cl2]⋅4 CHCl3}n(1) can be isolated. Anion‐exchange and organic‐group‐functionalized aromatic guest TTPE‐loaded host–guest complex experimental results indicate that coordinated Cl−anions in the 2D framework of1can be completely replaced with dissociative ClO4−groups in an irreversible single‐crystal‐to‐single‐crystal transformation fashion, as evidenced by the anion‐exchange products of {[Mn(TTPE)(H2O)2](ClO4)2⋅0.5 TTPE⋅5.25 H2O}n(2). Interestingly, TTPE, acting as an organic template, was encapsulated in the confined space of the 2D grid of2. To the best of our knowledge, such large organic molecules encapsulated in the reactive organic‐group‐functionalized aromatic‐guest‐loaded host–guest complex are unprecedented up to now. Luminescence measurements illustrate that1and2represent novel examples of sensing materials based on triazole derivatives. Further,2has been demonstrated by tuning the fluorescence response of porous metal–organic frameworks as a function of adsorbed small analytes.