bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ein enantiomerenreines metallosupramolekulares Pd4L8‐Aggregat mit neuartigem Strukturmotiv: Bildung durch einen Anionen‐Templateffekt
Authors: Klein Christoph , Gütz Christoph , Bogner Maximilian , Topić Filip , Rissanen Kari , Lützen Arne 
Published: March 2014

AbstractEin enantiomerenreiner Bis(3‐pyridyl)‐Ligand 1 auf der Basis eines BINOL‐Gerüsts bildet mit tetravalenten PdII‐Ionen einen homochiralen [Pd4(1)8]‐Komplex. Zwei Tetrafluoroborationen dienen dabei als Template für die Bildung dieses Aggegates und werden in zwei periphere Kavitäten eingeschlossen. Die dadurch resultierende Struktur repräsentiert ein neues Strukturmotiv für diese Sorte von metallosupramolekularen Assemblaten, in dem die vier Palladiumionen in einer verzerrt tetraedrischen Anordnung zu finden sind. Dies zwingt den Liganden 1, zwei verschiedene Konformationen in dem Aggregat einzunehmen. Beide Phänomene sind einzigartig und führen überdies zur Bildung einer dreidimensionalen Struktur, die noch über eine weitere, chirale und hydrophile zentrale Kavität verfügt.
Cationic Chains of Phosphanyl‐ and Arsanylboranes
Authors: Marquardt Christian , Thoms Christine , Stauber Andreas , Balázs Gábor , Bodensteiner Michael , Scheer Manfred 
Published: March 2014

AbstractWhilst catena‐phosphorus cations have been intensively studied in the last years, mixed Group 13/15 element cationic chains have not yet been reported. Reaction of the pnictogenboranes H2EBH2⋅NMe3 (E=P, As) with monohalideboranes lead to the cationic chain compounds [Me3N⋅BH2EH2BH2⋅NMe3][X] (E=P, As; X=AlCl4, I) and [Me3N⋅BH2PH2BH2PH2BH2⋅NMe3][X] (X=I, VCl4(thf)2), respectively. All of the compounds have been characterized by X‐ray structure analysis, NMR spectroscopy, IR spectroscopy, and mass spectrometry. DFT calculations elucidate the reaction pathway, the high thermodynamic stability, the charge distribution within the chain and confirm the observed solid‐state structures.
Highly Enantioselective Kinetic Resolution of Axially Chiral BINAM Derivatives Catalyzed by a Brønsted Acid
Authors: Cheng Dao‐Juan , Yan Liang , Tian Shi‐Kai , Wu Ming‐Yue , Wang Lu‐Xin , Fan Zi‐Li , Zheng Sheng‐Cai , Liu Xin‐Yuan , Tan Bin 
Published: March 2014

AbstractA highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid‐catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities.
Selective Host–Guest Interactions of a Transformable Coordination Capsule/Tube with Fullerenes
Authors: Kishi Norifumi , Akita Munetaka , Yoshizawa Michito 
Published: March 2014

AbstractAn M2L4 coordination capsule or an M2L2 coordination tube was selectively formed by the combination of HgII hinges and bent bispyridine ligands. The two structures reversibly interconvert at room temperature in response to modulation of the metal‐to‐ligand ratio and exhibit different host–guest interaction behavior. The capsule alone encapsulates large spherical molecules, fullerenes C60 and C70, and the bound guests are released upon capsule‐to‐tube transformation by the simple addition of metal ions.
Confining Phosphanes Derived from Cyclodextrins for Efficient Regio‐ and Enantioselective Hydroformylation
Authors: Jouffroy Matthieu , Gramage‐Doria Rafael , Armspach Dominique , Sémeril David , Oberhauser Werner , Matt Dominique , Toupet Loic 
Published: March 2014

AbstractTwo confining phosphane ligands derived from either α‐ or β‐cyclodextrin produce singly PIII‐ligated metal complexes with unusual coordination spheres. High‐pressure NMR studies have revealed that rhodium hydride complexes of the same type are also formed under hydroformylation conditions. This unique feature strongly favors the formation of the branched aldehyde at the expense of the linear one with high enantioselectivity in the rhodium‐catalyzed hydroformylation of styrene.
Click‐Assembled, Oxygen‐Sensing Nanoconjugates for Depth‐Resolved, Near‐Infrared Imaging in a 3 D Cancer Model
Authors: Nichols Alexander J. , Roussakis Emmanuel , Klein Oliver J. , Evans Conor L. 
Published: March 2014

AbstractHypoxia is an important contributing factor to the development of drug‐resistant cancer, yet few nonperturbative tools exist for studying oxygenation in tissues. While progress has been made in the development of chemical probes for optical oxygen mapping, penetration of such molecules into poorly perfused or avascular tumor regions remains problematic. A click‐assembled oxygen‐sensing (CAOS) nanoconjugate is reported and its properties demonstrated in an in vitro 3D spheroid cancer model. The synthesis relies on the sequential click‐based ligation of poly(amidoamine)‐like subunits for rapid assembly. Near‐infrared confocal phosphorescence microscopy was used to demonstrate the ability of the CAOS nanoconjugates to penetrate hundreds of micrometers into spheroids within hours and to show their sensitivity to oxygen changes throughout the nodule. This proof‐of‐concept study demonstrates a modular approach that is readily extensible to a wide variety of oxygen and cellular sensors for depth‐resolved imaging in tissue and tissue models.
Research on the preparation and antibacterial properties of 2‐N‐thiosemicarbazide‐6‐O‐hydroxypropyl chitosan membranes with iodine
Authors: Sai Mingze , Zhong Shiliang , Tang Yang , Ma Wentao , Sun Yangang , Ding Derun 
Published: March 2014

ABSTRACTThe 2‐N‐thiosemicarbazide‐6‐O‐hydroxypropyl chitosan (ATU‐HPCS) was prepared by chitosan grafted hydroxypropyl and thiosemicarbazide through the method of “amino protection‐graft‐deprotection,” while the ATU‐HPCS gel membranes were obtained from gelatin and polyvinyl pyrrolidone as additives, and the ATU‐HPCS membranes with iodine (ATU‐HPCS‐I2‐M) were prepared by adding the ethanol solution of iodine in the ATU‐HPCS gel membranes. The ATU‐HPCS‐I2‐M were characterized to evaluate their potential applications as antibacterial materials. The iodine releasing rule of ATU‐HPCS‐I2‐M showed a sustained‐release effect of iodine, the maximum emission was approximately 0.80%. The inhibition zone diameters of ATU‐HPCS‐I2‐M against Staphylococcus aureus (as Gram‐positive bacteria) and Escherichia coli (as Gram‐negative bacteria) were both greater than 15 mm, it demonstrated significant antibacterial activity compared with the ATU‐HPCS gel membranes. The double effects of the biocompatibility of chitosan and the sustained‐release of iodine provided an ideal healing environment for wound surface. These properties have made ATU‐HPCS‐I2‐M highly potential as a novel natural macromolecule antimicrobial material preventing the bacteria from burns, surgery wounds, etc. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40535.
A novel adsorbent obtained by caging activated carbon by konjac glucomannan gel for elimination of organic compounds
Authors: Dai Yingjie , Yan Hong , Zhang Binbin , Wu Wenting , Yang Liqiong , Li Shufeng , Li Wenbin , Li Hongtao , Yan Lilong , Shan Dexin , Feng Yujie , Terui Norifumi , Tanaka Shunitz 
Published: March 2014

ABSTRACTIn this study, the adsorptive ability of the konjac glucomannan gel containing activated carbon (KGMG–AC) was investigated by measuring the removal of several organic compounds with different charges, such as nitrobenzene (NB), methylene blue (MB), and rose bengale (RB). The physical and chemical properties, adsorption dynamics, adsorption isotherms, and the effect of pH of the adsorbents were compared with those of a commercially available powdered activated carbon (AC). The results of the present study indicate that the removal ratio of NB, MB, and RB onto KGMG–AC was slightly higher than that of the AC. The adsorption equilibrium constant (KL) value (0.02 L/mg) of KGMG–AC for NB was similar to that of AC (0.03 L/mg). However, the saturated adsorption amount (Q0) of KGMG–AC (368 mg/g) for NB was slightly larger than that of AC (354 mg/g). The saturated adsorption amounts of MB and RB on KGMG–AC were 302 and 259 mg/g, respectively. On the other hand, a high molecular weight humic acid was not adsorbed by KGMG–AC. Thus, entrapping AC into KGMG resulted in the selective adsorption. Therefore, this study could show that KGMG–AC was a new environmental friendly adsorbent that can be easily prepared, used, and recovered in environments. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2014,131, 40542.
Recent advances on polymer‐stabilized blue phase liquid crystal materials and devices
Authors: Chen Yuan , Wu Shin‐Tson 
Published: March 2014

ABSTRACTPolymer‐stabilized blue phase liquid crystals (PS‐BPLC) have become an increasingly important technology trend for information display and photonics applications. BPLCs exhibit several attractive features, such as reasonably wide temperature range, submillisecond gray‐to‐gray response time, no need for alignment layer, optically isotropic voltage‐off state, and large cell gap tolerance. However, some bottlenecks such as high operation voltage, hysteresis, residual birefringence, charging issues due to the large capacitance, and relatively low transmittance remain to be overcome before their widespread applications can be realized. Recent progress on BPLC materials and devices has shown great promise. To realize the electro‐optic effect of PS‐BPLC, two driving modes: in‐plane switching and vertical field switching mode, have been developed. The material system of PS‐BPLC, including nematic LC host, chiral dopant, and polymer network, are discussed. Each component plays an essential role affecting the stability and electro‐optic properties of PS‐BPLC. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40556.
Vicinal Difunctionalization of Alkenes with Iodine(III) Reagents and Catalysts
Authors: Romero R. Martín , Wöste Thorsten H. , Muñiz Kilian 
Published: March 2014

AbstractHypervalent iodine(III) reagents have been known for over a century, and their reaction profile is still actively investigated. Recent years have seen impressive improvements in the area of alkene difunctionalization reactions, where new methodologies have become available. Especially chiral non‐racemic hypervalent iodine(III) reagents and catalysts have emerged as versatile tools for the realization of important enantioselective transformations.
Druckstrebentragfähigkeit von vorgespannten UHPFRC‐Hohlkästen unter Torsion und kombinierter Beanspruchung
Authors: Oettel Vincent , Empelmann Martin 
Published: March 2014

AbstractAufgrund der hohen Druckfestigkeit von ultrahochfestem Faserbeton (UHPFRC) lassen sich sehr dünnwandige und innovative Bauelemente herstellen. Durch eine Vorfabrikation von transportgerechten und gewichtsoptimierten Segmenten, die später auf der Baustelle zu komplexen Bauteilen, wie z.B. Segmentbrücken, Fertigteiltürmen oder Fertigteilmasten zusammengespannt werden, könnten neue Anwendungsfelder für Betonbauteile erschlossen werden. Neben der Einwirkung aus Biegung und Querkraft treten in der späteren Nutzung auch Torsionsbeanspruchungen auf. Am iBMB, Fachgebiet Massivbau der TU Braunschweig, wurden experimentelle und theoretische Untersuchungen zur Druckstrebentragfähigkeit von monolithischen und segmentären extern vorgespannten Balken mit Hohlkastenquerschnitten aus UHPFRC unter Torsion sowie unter kombinierter Biege‐, Querkraft‐ und Torsionsbeanspruchung durchgeführt. Auf Basis der Versuchsergebnisse und unter Beachtung der Rechenansätze für normal‐ und hochfeste Betone wurden bestehende Bemessungsmodelle zur Beschreibung der Druckstrebentragfähigkeit für UHPFRC erweitert.Bearing capacity of the compression strut of prestressed UHPFRC box girders under torsion and combined loadingDue to the high compressive strength of ultra‐high performance fiber reinforced concrete (UHPFRC) thin‐walled and innovative components can be produced. In order to gain new fields of application for concrete elements it would be useful to prefabricate weight‐optimized and transportable segments, which could be mounted to complex components such as segmental bridges, precast towers or precast poles directly on site. As such components are not only stressed by bending and shear, but also torsion, the iBMB, Department of Concrete Structures of the TU Braunschweig, has conducted experimental and theoretical research works on the bearing capacity of the concrete compression strut of monolithic and segmental externally prestressed UHPFRC box girders under torsion and combined loading of bending, shear and torsion. Based on the experimental results and the approaches of normal‐ and high‐strength concrete the existing design models have been extended to describe the bearing capacity of UHPFRC compression struts.
Tailoring the Cooperative Acid–Base Effects in Silica‐Supported Amine Catalysts: Applications in the Continuous Gas‐Phase Self‐Condensation of n‐Butanal
Authors: Shylesh Sankaranarayanapillai , Hanna David , Gomes Joseph , Krishna Siddarth , Canlas Christian G. , Head‐Gordon Martin , Bell Alexis T. 
Published: March 2014

AbstractA highly efficient solid‐base organocatalyst for the gas‐phase aldol self‐condensation of n‐butanal to 2‐ethylhexenal was developed by grafting site‐isolated amines on tailored silica surfaces. The catalytic activity depends largely on the nature of amine species, the surface concentration of amine and silanol groups, and the spatial separation between the silanol and amine groups. In situ FTIR measurements demonstrated that the formation of nucleophilic enamines leads to the enhanced catalytic activity of secondary amine catalysts, whereas the formation of imines (stable up to 473 K) leads to the low activity observed for silica‐supported primary amines. Blocking the silanol groups on the silica support by silylation or cofeeding water into the reaction stream drastically decreased the reaction rates, demonstrating that weaker acidic silanol groups participate cooperatively with the amine groups to catalyze the condensation reaction. This work demonstrates that the spatial separation of the weakly acidic silanols and amines can be tuned by the controlled dehydration of the supporting silica and by varying the linker length of the amine organosilane precursor used to graft the amine to the support surface. A mechanism for aldol condensation was proposed and then analyzed by DFT calculations. DFT analysis of the reaction pathway suggested that the rate‐limiting step in aldol condensation is carboncarbon bond formation, which is consistent with the observed kinetics. The calculated apparent activation barrier agrees reasonably with that measured experimentally.
Electrostatic and Non‐covalent Interactions in Dicationic Imidazolium–Sulfonium Salts with Mixed Anions
Authors: Fei Zhaofu , Zhu Dun‐Ru , Yan Ning , Scopelliti Rosario , Katsuba Sergey A. , Laurenczy Gabor , Chisholm Danielle M. , McIndoe J. Scott , Seddon Kenneth R. , Dyson Paul J. 
Published: March 2014

AbstractA series of thioether‐functionalised imidazolium salts have been prepared and characterized. Subsequent reaction of the thioether‐functionalised imidazolium salts with iodomethane affords imidazolium–sulfonium salts composed of doubly charged cations and two different anions. Imidazolium–sulfonium salts containing a single anion type are obtained either by a solvent extraction method or by anion exchange. The imidazolium–sulfonium salts undergo a methyl‐transfer reaction on exposure to water, giving rise to a new, singly charged imidazolium salt with iodide introduced at the 2‐position of the imidazolium ring. Crystal structures of some of the imidazolium–sulfonium salts were determined by X‐ray crystallography providing the topology of the interactions between the dications and the anions. Electrospray ionization mass spectrometry and quantum‐chemical calculations were used to rationalise the relative strength of these interactions.
Solvent‐Dependent Self‐Assembly Behaviour and Speciation Control of Pd6L8 Metallo‐supramolecular Cages
Authors: Henkelis James J. , Fisher Julie , Warriner Stuart L. , Hardie Michaele J. 
Published: March 2014

AbstractThe C3‐symmetric chiral propylated host‐type ligands (±)‐tris(isonicotinoyl)‐tris(propyl)‐cyclotricatechylene (L1) and (±)‐tris(4‐pyridyl‐4‐benzoxy)‐tris(propyl)‐cyclotricatechylene (L2) self‐assemble with PdII into [Pd6L8]12+ metallo‐cages that resemble a stella octangula. The self‐assembly of the [Pd6(L1)8]12+ cage is solvent‐dependent; broad NMR resonances and a disordered crystal structure indicate no chiral self‐sorting of the ligand enantiomers in DMSO solution, but sharp NMR resonances occur in MeCN or MeNO2. The [Pd6(L1)8]12+ cage is observed to be less favourable in the presence of additional ligand, than is its counterpart, where L=(±)‐tris(isonicotinoyl)cyclotriguaiacylene (L1 a). The stoichiometry of reactant mixtures and chemical triggers can be used to control formation of mixtures of homoleptic or heteroleptic [Pd6L8]12+ metallo‐cages where L=L1 and L1 a.
SiO2/TiO2 Hollow Nanoparticles Decorated with Ag Nanoparticles: Enhanced Visible Light Absorption and Improved Light Scattering in Dye‐Sensitized Solar Cells
Authors: Hwang Sun Hye , Shin Dong Hoon , Yun Juyoung , Kim Chanhoi , Choi Moonjung , Jang Jyongsik 
Published: March 2014

AbstractHollow SiO2/TiO2 nanoparticles decorated with Ag nanoparticles (NPs) of controlled size (Ag@HNPs) were fabricated in order to enhance visible‐light absorption and improve light scattering in dye‐sensitized solar cells (DSSCs). They exhibited localized surface plasmon resonance (LSPR) and the LSPR effects were significantly influenced by the size of the Ag NPs. The absorption peak of the LSPR band dramatically increased with increasing Ag NP size. The LSPR of the large Ag NPs mainly increased the light absorption at short wavelengths, whereas the scattering from the SiO2/TiO2 HNPs improved the light absorption at long wavelengths. This enabled the working electrode to use the full solar spectrum. Furthermore, the SiO2 layer thickness was adjusted to maximize the LSPR from the Ag NPs and avoid corrosion of the Ag NPs by the electrolyte. Importantly, the power conversion efficiency (PCE) increased from 7.1 % with purely TiO2‐based DSSCs to 8.1 % with HNP‐based DSSCs, which is an approximately 12 % enhancement and can be attributed to greater light scattering. Furthermore, the PCEs of Ag@HNP‐based DSSCs were 11 % higher (8.1 vs. 9.0 %) than the bare‐HNP‐based DSSCs, which can be attributed to LSPR. Together, the PCE of Ag@HNP‐based DSSCs improved by a total of 27 %, from 7.1 to 9.0 %, due to these two effects. This comparative research will offer guidance in the design of multifunctional nanomaterials and the optimization of solar‐cell performance.
Acetylcholine‐Triggered Cargo Release from Supramolecular Nanovalves Based on Different Macrocyclic Receptors
Authors: Zhou Yue , Tan Li‐Li , Li Qing‐Lan , Qiu Xi‐Long , Qi Ai‐Di , Tao Yanchun , Yang Ying‐Wei 
Published: March 2014

AbstractAcetylcholine (ACh), a neurotransmitter located in cholinergic synapses, can trigger cargo release from mesoporous silica nanoparticles equipped with calixarene‐ or pillarene‐based nanovalves by removing macrocycles from the stalk components. The amount and speed of cargo release can be controlled by varying the concentration of ACh in solution or changing the type of gating macrocycle. Although this proof‐of‐concept study is far from a real‐life application, it provides a possible route to treat diseases related to the central nervous system.
Synthesis of Indazoles and Azaindazoles by Intramolecular Aerobic Oxidative CN Coupling under Transition‐Metal‐Free Conditions
Authors: Hu Jiantao , Xu Huacheng , Nie Pengju , Xie Xiaobo , Nie Zongxiu , Rao Yu 
Published: March 2014

AbstractA transition‐metal‐free oxidative CN coupling method has been developed for the synthesis of 1H‐azaindazoles and 1H‐indazoles from easily accessible hydrazones. The procedure uses TEMPO, a basic additive, and dioxygen gas as the terminal oxidant. This reaction demonstrates better reactivity, functional group tolerance, and broader scope than comparable metal catalyzed reactions.
HPLC‐Fluorescence Method for the Enantioselective Analysis of Propranolol in Rat Serum Using Immobilized Polysaccharide‐Based Chiral Stationary Phase
Authors: Alanazi Amer M. , Hefnawy Mohamed M. , AL‐Majed Abdulrahman A. , AL‐ Suwailem Aymen K. , Kassem Mohamed G. , Mostafa Gamal A. , Attia Sabry M. , Khedr Mohammed M. 
Published: March 2014

ABSTRACTA stereoselective high‐performance liquid chromatographic (HPLC) method was developed and validated to determine S‐(−)‐ and R‐(+)‐propranolol in rat serum. Enantiomeric resolution was achieved on cellulose tris(3,5‐dimethylphenylcarbamate) immobilized onto spherical porous silica chiral stationary phase (CSP) known as Chiralpak IB. A simple analytical method was validated using a mobile phase consisted of n‐hexane‐ethanol‐triethylamine (95:5:0.4%, v/v/v) at a flow rate of 0.6 mL min‐1 and fluorescence detection set at excitation/emission wavelengths 290/375 nm. The calibration curves were linear over the range of 10–400 ng mL‐1 (R = 0.999) for each enantiomer with a detection limit of 3 ng mL‐1. The proposed method was validated in compliance with ICH guidelines in terms of linearity, accuracy, precision, limits of detection and quantitation, and other aspects of analytical validation. Actual quantification could be made for propranolol isomers in serum obtained from rats that had been intraperitoneally (i.p.) administered a single dose of the drug. The proposed method established in this study is simple and sensitive enough to be adopted in the fields of clinical and forensic toxicology. Molecular modeling studies including energy minimization and docking studies were first performed to illustrate the mechanism by which the active enantiomer binds to the β‐adrenergic receptor and second to find a suitable interpretation of how both enantiomers are interacting with cellulose tris(3,5‐dimethylphenylcarbamate) CSP during the process of resolution. The latter interaction was demonstrated by calculating the binding affinities and interaction distances between propranolol enantiomers and chiral selector. Chirality 26:194–199, 2014. © 2014 Wiley Periodicals, Inc.
Development and Screening of a Series of Antibody‐Conjugated and Silica‐Coated Iron Oxide Nanoparticles for Targeting the Prostate‐Specific Membrane Antigen
Authors: Mukherjee Amarnath , Darlington Thomas , Baldwin Richard , Holz Charles , Olson Sage , Kulkarni Prakash , DeWeese Theodore L. , Getzenberg Robert H. , Ivkov Robert , Lupold Shawn E. 
Published: March 2014

AbstractThe prostate‐specific membrane antigen (PSMA) is an established target for the delivery of cancer therapeutic and imaging agents due to its high expression on the surface of prostate cancer cells and within the neovasculature of other solid tumors. Here, we describe the synthesis and screening of antibody‐conjugated silica‐coated iron oxide nanoparticles for PSMA‐specific cell targeting. The humanized anti‐PSMA antibody, HuJ591, was conjugated to a series of nanoparticles with varying densities of polyethylene glycol and primary amine groups. Customized assays utilizing iron spectral absorbance and enzyme‐linked immunoassay (ELISA) were developed to screen microgram quantities of nanoparticle formulations for immunoreactivity and cell targeting ability. Antibody and PSMA‐specific targeting of the optimized nanoparticle was evaluated using an isogenic PSMA‐positive and PSMA‐negative cell line pair. Specific nanoparticle targeting was confirmed by iron quantification with inductively coupled plasma mass spectrometry (ICP‐MS). These methods and nanoparticles support the promise of targeted theranostic agents for future treatment of prostate and other cancers.