bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ruthenium‐Catalyzed Reductive Methylation of Imines Using Carbon Dioxide and Molecular Hydrogen
Authors: Beydoun Kassem , Ghattas Ghazi , Thenert Katharina , Klankermayer Jürgen , Leitner Walter 
Published: August 2014

AbstractThe use of the well‐defined [Ru(triphos)(tmm)] catalyst, CO2 as C1 source, and H2 as reducing agent enabled the reductive methylation of isolated imines, as well as the direct coupling of amines with aldehydes and the subsequent reductive methylation of the in situ formed imines. The method, which afforded the corresponding N‐methyl amines in very good to excellent yields, was also used for the preparation of the antifungal agent butenafine in one step with no apparent waste, thus increasing the atom efficiency of its synthesis.
A Tetrameric Cage with D2h Symmetry through Alkyne Metathesis
Authors: Wang Qi , Zhang Chenxi , Noll Bruce C. , Long Hai , Jin Yinghua , Zhang Wei 
Published: August 2014

AbstractShape‐persistent covalent organic polyhedrons (COPs) with ethynylene linkers are usually prepared through kinetically controlled cross‐coupling reactions. The high‐yielding synthesis of ethynylene‐linked rigid tetrameric cages via one‐step alkyne metathesis from readily accessible triyne precursors is presented. The tetrameric cage contains two macrocyclic panels and exhibits D2h symmetry. The assembly of such a COP is a thermodynamically controlled process, which involves the initial formation of macrocycles as key intermediates followed by the connection of two macrocycles with ethynylene linkages. With a large internal cavity, the cage exhibits a high binding selectivity toward C70 (K=3.9×103 L mol−1) over C60 (no noticeable binding).
Asymmetric Alkynylation/Lactamization Cascade: An Expeditious Entry to Enantiomerically Enriched Isoindolinones
Authors: Bisai Vishnumaya , Suneja Arun , Singh Vinod K. 
Published: August 2014

AbstractAn unprecedented CuI–pybox‐diPh‐catalyzed highly enantioselective (up to >99 % ee) alkynylation/lactamization cascade has been developed as a general catalytic system for the synthesis of diversely substituted isoindolinones of immense biological importance. The cascade effects one CC and two CN bond‐forming events in one reaction vessel under operationally simple, additive‐free reaction conditions in good to excellent yields. The methodology was further extended to the synthesis of tetrahydroisoquinoline scaffolds common to several biologically active natural products in a two‐step sequence with remarkable selectivity (up to 94 % ee).
A Multitasking Vanadium‐Dependent Chloroperoxidase as an Inspiration for the Chemical Synthesis of the Merochlorins
Authors: Diethelm Stefan , Teufel Robin , Kaysser Leonard , Moore Bradley S. 
Published: August 2014

AbstractThe vanadium‐dependent chloroperoxidase Mcl24 was discovered to mediate a complex series of unprecedented transformations in the biosynthesis of the merochlorin meroterpenoid antibiotics. In particular, a site‐selective naphthol chlorination is followed by an oxidative dearomatization/terpene cyclization sequence to build up the stereochemically complex carbon framework of the merochlorins in one step. Inspired by the enzyme reactivity, a chemical chlorination protocol paralleling the biocatalytic process was developed. These chemical studies led to the identification of previously overlooked merochlorin natural products.
Synthesis and Self‐Assembly of Thermoresponsive Amphiphilic Biodegradable Polypeptide/Poly(ethyl ethylene phosphate) Block Copolymers
Authors: Wu Qiuhua , Zhou Dan , Kang Renyu , Tang Xiuping , Yang Qi , Song Ximing , Zhang Guolin 
Published: August 2014

AbstractWe report the design and synthesis of new fully biodegradable thermoresponsive amphiphilic poly(γ‐benzyl L‐glutamate)/poly(ethyl ethylene phosphate) (PBLG‐b‐PEEP) block copolymers by ring‐opening polymerization of N‐carboxy‐γ‐benzyl L‐glutamate anhydride (BLGNCA) with amine‐terminated poly(ethyl ethylene phosphate) (H2NPEEP) as a macroinitiator. The fluorescence technique demonstrated that the block copolymers could form micelles composed of a hydrophobic core and a hydrophilic shell in aqueous solution. The morphology of the micelles as determined by transmission electron microscopy (TEM) was spherical. The size and critical micelle concentration (CMC) values of the micelles showed a decreasing trend as the PBLG segment increased. However, UV/Vis measurements showed that these block copolymers exhibited a reproducible temperature‐responsive behavior with a lower critical solution temperature (LCST) that could be tuned by the block composition and the concentration.
Efficient Red Electroluminescent Devices with Sterically Hindered Phosphorescent Platinum(II) Schiff Base Complexes and Iridium Complex Codopant
Authors: Zhou Liang , Kwong Chun‐Lam , Kwok Chi‐Chung , Cheng Gang , Zhang Hongjie , Che Chi‐Ming 
Published: August 2014

AbstractSterically hindered platinum(II) Schiff base complexes were prepared. Complex 4, which displays red emission with a quantum yield of 0.29 in a thin film and a self‐quenching rate constant of 1×10−7 dm3 mol−1 s−1, was used to fabricate organic light‐emitting diodes with single or double emissive layers (EMLs). An iridium(III) complex with a wide band gap was codoped into the electron‐dominant EML to act as a deep electron trapper, and red‐light‐emitting devices with the highest current, power, and external quantum efficiencies of 20.43 cd A−1 18.33 Lm W−1, and 11.7 %, respectively, were fabricated. A high current efficiency and EQE of up to 14.69 cd A−1 and 8.3 %, respectively, were achieved at a high brightness of 1000 cd m−2. The significant delay of efficiency roll‐off is attributed to the bulky 3D structure of the norbornene moiety at the periphery of the Schiff base ligand of 4 and to the new device design strategy. The fabricated device had a projected lifetime (LT50) of 18 000 h.
Chirality Control of Quadruple Helixes of Metal Strings by Peripheral Chiral Ligands
Authors: Yu Chung‐Han , Kuo Min‐Shiang , Chuang Ching‐Yi , Lee Gene‐Hsiang , Hua Shao‐An , Jin Bih‐Yaw , Peng Shie‐Ming 
Published: August 2014

AbstractChirality control of helixes with the Δ (P) or Λ (M) form is interesting in various fields such as extended metal atom chains (EMACs), in which the metal backbones are helically wrapped by four ligands. Herein, we report two EMACs, Δ‐[Ni5((−)camnpda)4] and Λ‐[Ni5((+)camnpda)4], whose chiralities are controlled by chiral ligands with naphthyridine and camphorsulfonyl groups. There is a large energy difference (108 kcal mol−1) between the two helical structures with one chiral ligand. Furthermore, the electron communication between [Ni2]3+ units is more pronounced than in [Ni5(bna)4Cl2]2+ (bna=binaphthyridylamido). The results demonstrate control of small‐scale helical structure and set the stage for future development of chiral controlled base and nanoelectronic devices.
Event‐triggered Control of Linear Systems with Saturated Inputs
Authors: Ni Wei , Zhao Ping , Wang Xiaoli , Wang Jinhuan 
Published: August 2014

AbstractThis paper investigates the event‐triggered control of linear systems with saturated state feedback and saturated observer‐based feedback, respectively. The problem of simultaneously deriving stabilizing event‐triggered controllers and tackling saturation nonlinearity is cast into a standard linear matrix inequalities problem. Key topics are studied, such as event‐triggered observer design and event‐triggered saturated observer‐based feedback synthesis. Important issues are touched on, including the existence of the positive lower bound for inter‐event times, and self‐triggered algorithms.
Pregnancy incidence and outcome before and after cervical intraepithelial neoplasia: a retrospective cohort study
Authors: Kalliala Ilkka , Anttila Ahti , Nieminen Pekka , Halttunen Mervi , Dyba Tadeusz 
Published: August 2014

AbstractWe performed a retrospective cohort study of 3530 women treated for cervical intraepithelial neoplasia (CIN) in Helsinki University Central Hospital, Finland, to investigate whether CIN treatment itself affects pregnancy incidence and outcome. We estimated the incidence of live births, miscarriages, extrauterine pregnancies, molar pregnancies, and termination of pregnancies (TOPs) before and after CIN treatment using nationwide registers. Women were followed up until death, emigration, sterilization, or the end of 2004. The comparison of incidence of pregnancy outcomes before and after the treatment was estimated by calculating hazard ratios (HRs) with conditional Poisson regression. After 76,162 woman‐years of follow‐up, the incidence of any pregnancy remained constant over CIN‐treatment, HR 1.02 and 95% confidence interval (CI) 0.97–1.08, but the incidence of the first pregnancy was significantly elevated after treatment, HR 1.13, and 95% CI 1.03–1.23. The incidence of live births was significantly elevated after treatment, HR 1.08 and 95% CI 1.01–1.15. Incidence of miscarriages, TOPs, extrauterine pregnancies, and molar pregnancies was not elevated. TOPs was significantly increased in the first pregnancy, HR 1.40, 95% CI 1.15–1.72 and after treatment by the loop electrosurgical excision procedure (LEEP), HR 1.36, 95% CI 1.15–1.60. CIN treatment did not reduce pregnancy incidence and women had more live births after than before CIN treatment. TOPs was more common in the first pregnancy or after treatment by LEEP. We encourage research on the psychosocial consequences of CIN treatment also in other countries and settings.
Peptidyl Succinimidyl Peptides as Taspase 1 Inhibitors
Authors: van den Boom Johannes , Mamić Marija , Baccelliere Daniele , Zweerink Susanne , Kaschani Farnusch , Knauer Shirley , Bayer Peter , Kaiser Markus 
Published: August 2014

AbstractTaspase 1 is an N‐terminal threonine protease implicated in leukemia and other cancers. Despite intensive efforts in recent years, only a limited number of Taspase 1 inhibitors are currently available, and they lack general applicability. Here we present a novel class of Taspase 1 inhibitors based on a peptidyl succinimidyl peptide motif. These inhibitors were obtained from the substrate cleavage sequence and mechanistic considerations involving the previously proposed asparaginase‐type cleavage mechanism. We anticipate that this class of Taspase 1 inhibitor will find wide application in further biochemical and structural studies, for example for better investigating the molecular details of the unusual enzymatic cleavage mechanism of Taspase 1.
Heterologous Production of Glidobactins/Luminmycins in Escherichia coli Nissle Containing the Glidobactin Biosynthetic Gene Cluster from Burkholderia DSM7029
Authors: Bian Xiaoying , Huang Fan , Wang Hailong , Klefisch Thorsten , Müller Rolf , Zhang Youming 
Published: August 2014

AbstractNatural product peptide‐based proteasome inhibitors show great potential as anticancer drugs. Here we have cloned the biosynthetic gene cluster of a potent proteasome inhibitor—glidobactin from Burkholderia DSM7029—and successfully detected glidobactins/luminmycins in E. coli Nissle. We have also improved the yield of glidobactin A tenfold by promoter change in a heterologous host. In addition, two new biosynthetic intermediates were identified by comparative MS/MS fragmentation analysis. Identification of acyclic luminmycin E implies substrate specificity of the TE domain for cyclization. The establishment of a heterologous expression system for syrbactins provided the basis for the generation of new syrbactins as proteasome inhibitors by molecular engineering, but the TE domain's specificity cannot be ignored.
Pd/CeO2−x Nanorod Catalysts for CO Oxidation: Insights into the Origin of Their Regenerative Ability at Room Temperature
Authors: Zhou Yunyun , Lawrence Neil J. , Wu Tai‐Sing , Liu Jing , Kent Patrick , Soo Yun‐Liang , Cheung Chin Li 
Published: August 2014

AbstractThe decrease in the activity of a catalyst after use is a persistent challenge in the chemical industry. We report that palladium‐decorated ceria (Pd/CeO2−x, in which 0≤x<0.5) nanorod catalysts demonstrate regenerative ability for carbon monoxide oxidation at room temperature. Pd/CeO2−x catalysts with 75 % decreased catalytic activity can be regenerated and restored almost 100 % of their original catalytic activity by exposing them to ambient conditions for 24 h. X‐ray spectroscopy studies of the atomic structures and oxidation states of palladium in the catalyst found that the formation of disordered palladium oxide is partly accountable for its observed regenerative catalytic property.
Aqueous Phase Hydrogenation of Quinoline to Decahydroquinoline Catalyzed by Ruthenium Nanoparticles Supported on Glucose‐Derived Carbon Spheres
Authors: Zhu Deming , Jiang Hongbin , Zhang Lei , Zheng Xueli , Fu Haiyan , Yuan Maolin , Chen Hua , Li Ruixiang 
Published: August 2014

AbstractA new ruthenium catalyst supported on glucose‐derived carbon spheres was prepared by using the impregnation method and then characterized by X‐ray photoelectron spectroscopy, XRD, TEM, SEM, FTIR, and solid‐state 13C MAS NMR techniques. With water as the environmentally friendly solvent, the conversion of quinoline and the selectivity toward decahydroquinoline could reach 98.2 and 95.2 %, respectively, under mild conditions (reaction temperature=393 K and H2 pressure=2.0 MPa). The catalyst could be recycled thrice without decrease in activity and selectivity. The excellent catalytic performance of this catalyst may be attributed to the hydrogen bond between the hydroxyl group of the support surface and the nitrogen atom in quinoline as well as to the π–π interaction between the organic support and quinoline.
Coupled Electrokinetic Transport and Electron Transfer at Annular Nanoband Electrodes Embedded in Cylindrical Nanopores
Authors: Zaino Lawrence P. , Contento Nicholas M. , Branagan Sean P. , Bohn Paul W. 
Published: August 2014

AbstractConvective mass transport is achieved in nanopore arrays containing embedded annular nanoband electrodes (EANEs) by using both two‐ and three‐electrode systems. In the two‐electrode configuration, the potential drop between the EANE and a counter/quasi‐reference electrode (CE/QRE) controls the electro‐osmotic flow (EOF). EOF enhances the rate of electron‐transfer reactions at an EANE array. Three‐electrode configurations, in which the EANE is placed between the CE/QRE and a second working electrode (WE2), are also studied. In the three‐electrode configuration, the position and magnitude of the current peaks are dependent on the WE2 potential. These shifts, which are characteristic of strong coupling between the EOF caused by WE2 and the faradaic processes monitored at the EANE, are explained by a combination of EOF and the concentration of analyte in the nanochannel. EOF is dictated collectively by the EANE and the WE2, because the potential at both electrodes is modified by substantial iR drops in the high‐resistance nanopores.
Photo‐bioelectrochemical Cells for Energy Conversion, Sensing, and Optoelectronic Applications
Authors: Tel‐Vered Ran , Willner Itamar 
Published: August 2014

AbstractThe native photosynthetic reaction centers photosystem I (PSI) and photosystem II (PSII) act as functional nanostructures for the assembly of photo‐biofuel cells. By electrical wiring of PSI and/or PSII with electrodes, the conversion of light energy into electrical power has been demonstrated. Different methodologies to electrically contact the photosystems with the electrodes have been developed, including the reconstitution of the photosystems on relay units, the application of redox‐active polymers as charge‐transport matrices, and the use of metallic nanoparticles or nanoclusters as electron‐transfer relays. Electrical contact of the photosystems with the electrodes facilitates charge separation of the redox intermediates generated upon illumination of the assemblies, thus retarding destructive back electron‐transfer reactions and enhancing the conversion of light energy into electrical power. Recent advances to fabricate electrically wired PSI and/or PSII electrodes are surveyed, and different approaches to assemble photo‐bioelectrochemical cells are discussed. The limitations and future perspectives of the systems will also be presented.
A Highly Stable and Active Hybrid Cathode for Low‐Temperature Solid Oxide Fuel Cells
Authors: Liang Fengli , Zhou Wei , Zhu Zhonghua 
Published: August 2014

AbstractImproving the sluggish oxygen reduction reaction (ORR) is vital to enable the commercialization of some high‐temperature clean‐energy devices. Silver (Ag) is usually decorated onto the surface of electrodes to enhance ORR activity. However, the thermal instability of Ag causes the deactivation of ORR on coarsened particles under operating conditions. Here, we introduce a SrSc0.175Nb0.025Co0.8O3−δ (SSNC) perovskite hybrid cathode decorated with Ag@CeO2 core–shell spheres, which shows an extremely high performance for the ORR. Its area‐specific resistance is just 0.24 Ω cm2 at 500 °C, and it works stably under a cathodic polarization at 600 °C for over 110 h, without detectable performance deterioration. Electron microscopy reveals that the Ag cores remain isolated even after heating the catalyst to 800 °C. The design concept in this work can be extended to prevent the aggregation of other metallic electrocatalysts working at high temperatures.
Molecular Function of Counting the Numbers 1 and 2 Exhibited by a Sulfoneamidohelicene Tetramer
Authors: Shigeno Masanori , Kushida Yo , Kobayashi Yuta , Yamaguchi Masahiko 
Published: August 2014

AbstractThe sulfoneamidohelicene tetramer in solution exhibits different molecular responses to the same cooling stimulus delivered once and twice under thermal hysteresis conditions. Its random‐coil state at a high temperature was cooled and maintained at a given temperature for which its molecules remained in a random coil (first cooling); the resulting solution was heated and cooled, after which a helix dimer formed (second cooling). Such a property can be regarded as a molecular function of counting the numbers 1 and 2.
Dimers and Trimers of Diphosphenes: A Wealth of Cyclo‐Phosphanes
Authors: Bresien Jonas , Hering Christian , Schulz Axel , Villinger Alexander 
Published: August 2014

AbstractVarious new P‐based ring systems were synthesised by transferring established reaction routes from NP chemistry to the analogous PP compounds. Due to the different electronic situations of phosphorus and nitrogen with respect to s and p character of the lone pair, different reactivity of the phosphorus compounds was observed, especially with regard to the specificity of the reactions and the stability of the products. Whereas Mes*NPCl (Mes*=2,4,6‐tri‐tert‐butylphenyl) is stable in the solid state and in solution, the formal phosphorus congener Mes*PPCl is highly reactive and could not be observed. Instead, several formal dimers and trimers of Mes*PPCl could be isolated, which constitute an intriguing variety of three‐ and four‐membered ring systems.
Synthesis and Photophysical Properties of Multichromophoric Carbonyl‐Bridged Triarylamines
Authors: Haedler Andreas T. , Beyer Sebastian R. , Hammer Natalie , Hildner Richard , Kivala Milan , Köhler Jürgen , Schmidt Hans‐Werner 
Published: August 2014

AbstractThe synthesis and photophysical properties of two novel multichromophoric compounds is presented. Their molecular design comprises a carbonyl‐bridged triarylamine core and either naphthalimides or 4‐(5‐hexyl‐2,2′‐bithiophene)naphthalimides as second chromophore in the periphery. The lateral chromophores are attached to the core via an amide linkage and a short alkyl spacer. The synthetic approach demonstrates a straightforward functionalization strategy for carbonyl‐bridged triarylamines. Steady‐state and time‐resolved spectroscopic investigations of these compounds, in combination with three reference compounds, provide clear evidence for energy transfer in both multichromophoric compounds. The direction of the energy transfer depends on the lateral chromophore used. Furthermore, the compound bearing the lateral 4‐(bithiophene)naphthaimides is capable of forming fluorescent gels at very low concentrations in the sub‐millimolar regime whilst retaining its energy transfer properties.
Development of a Mild and Versatile Directed Cycloaddition Approach to Pyridines
Authors: Bachollet Sylvestre P. J. T. , Vivat Jérôme F. , Cocker Dean C. , Adams Harry , Harrity Joseph P. A. 
Published: August 2014

AbstractThe aza‐Diels–Alder cycloaddition of 1,2,4‐triazines with alkynes offers a rapid and convenient method for the synthesis of highly substituted pyridines, but often requires harsh conditions and long reaction times. The present study offers a solution to these limitations by use of a temporary tether established by a Lewis acid–base complexation of in situ generated alkynylboranes and triazines bearing a Lewis basic donor. The cycloaddition reactions take place within 20 min at 40 °C and provide direct access to a broad range of pyridines with complete and predictable regiocontrol. The carbonboron bond can be further functionalised by cross‐coupling allowing further functionality to be introduced after cycloaddition.
Iridium(III)‐Catalyzed CH Amidation of Arylphosphoryls Leading to a P‐Stereogenic Center
Authors: Gwon Donghyeon , Lee Donggun , Kim Jiyu , Park Sehoon , Chang Sukbok 
Published: August 2014

AbstractDirect CH amidation of arylphosphoryl compounds has been developed by using an IrIII catalyst system under mild conditions. A wide range of substrates could be employed with high functional‐group tolerance. This procedure was successfully applied for the first time to the asymmetric reaction giving rise to a P‐chirogenic center with a high diastereomeric ratio of up to 19:1 (90 % de).
Activation of SO2 and CO2 by Trivalent Uranium Leading to Sulfite/Dithionite and Carbonate/Oxalate Complexes
Authors: Schmidt Anna‐Corina , Heinemann Frank W. , Kefalidis Christos E. , Maron Laurent , Roesky Peter W. , Meyer Karsten 
Published: August 2014

AbstractThe first sulfite [{((nP,MeArO)3tacn)UIV}2(μ‐κ1:κ2‐SO3)] (tacn=triazacyclononane) and dithionite [{((nP,MeArO)3tacn)UIV}2(μ‐κ2:κ2‐S2O4)] complexes of uranium from reaction with gaseous SO2 have been prepared. Additionally, the reductive activation of CO2 was investigated with respect to the rare oxalate [{((nP,MeArO)3tacn)UIV}2(μ‐κ2:κ2‐C2O4)] formation. This ultimately provides the unique S2O42−/C2O42− and SO32−/CO32− complex pairs. All new complexes were characterized by a combination of single‐crystal X‐ray diffraction, elemental analysis, UV/Vis/NIR electronic absorption, IR vibrational, and 1H NMR spectroscopy, as well as magnetization (VT SQUID) studies. Moreover, density functional theory (DFT) calculations were carried out to gain further insight into the reaction mechanisms. All observations, together with DFT, support the assumption that SO2 and CO2 show similar (dithionite/oxalate) to analogous (sulfite/carbonate) activation behavior with uranium complexes.
ChemInform Abstract: Synthesis, Characterization and Optical Properties of NH4Dy(PO3)4.
Authors: Chemingui S. , Ferhi M. , Horchani‐Naifer K. , Ferid M. 
Published: August 2014

AbstractPolycrystalline NH4Dy(PO3)4 is grown from a mixture of Dy2O3 and excess (NH4)2HPO4 acting as reactive flux (350 °C, 2 d) and further transformed to Dy(PO3)3 by calcination (800 °C, 2 h).
ChemInform Abstract: Stabilization by Si Substitution of the Pseudobinary Compound Gd2(Co3‐xSix) with Magnetocaloric Properties Around Room Temperature.
Authors: Tence Sophie , Caballero Flores Rafael , Chable Johann , Gorsse Stephane , Chevalier Bernard , Gaudin Etienne 
Published: August 2014

AbstractThe new solid solution Gd2(Co3‐xSix) (0.29 < x < 0.50) is obtained by arc‐melting of the elements.
ChemInform Abstract: Synthesis of Metastable SiIIX2 Solutions (X: F, Cl). A Novel Binary Halide for Synthesis.
Authors: Uhlemann Fabian , Koeppe Ralf , Schnepf Andreas 
Published: August 2014

AbstractSiF2 (I) as well as SiCl2 (II) are prepared in the gas phase from Si and SiF4 (SiCl4) at 1510 °C (I) resp.