bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visualizing the Stoichiometry of Industrial‐Style Co‐Mo‐S Catalysts with Single‐Atom Sensitivity
Authors: Zhu Yuanyuan , Ramasse Quentin M. , Brorson Michael , Moses Poul G. , Hansen Lars P. , Kisielowski Christian F. , Helveg Stig 
Published: July 2014

AbstractThe functional properties of transition metal dichalcogenides (TMDs) may be promoted by the inclusion of other elements. Here, we studied the local stoichiometry of single cobalt promoter atoms in an industrial‐style MoS2‐based hydrotreating catalyst. Aberration‐corrected scanning transmission electron microscopy and electron energy loss spectroscopy show that the Co atoms occupy sites at the (−100) S edge terminations of the graphite‐supported MoS2 nanocrystals in the catalyst. Specifically, each Co atom has four neighboring S atoms that are arranged in a reconstructed geometry, which reflects an equilibrium state. The structure agrees with complementary studies of catalysts that were prepared under vastly different conditions and on other supports. In contrast, a small amount of residual Fe in the graphite is found to compete for the S edge sites, so that promotion by Co is strongly sensitive to the purity of the raw materials. The present single‐atom‐sensitive analytical method therefore offers a guide for advancing preparative methods for promoted TMD nanomaterials.
Sequential Logic Operations with a Molecular Keypad Lock with Four Inputs and Dual Fluorescence Outputs
Authors: Jiang Xiong‐Jie , Ng Dennis K. P. 
Published: July 2014

AbstractA novel coumarin–rhodamine conjugate was prepared, and its metal binding properties were studied by UV/Vis and fluorescence spectroscopy. The conjugate serves as a ratiometric and highly selective fluorescent sensor for Hg2+ ions. Its metal‐responsive spectral properties were utilized to construct a molecular keypad lock with four inputs and dual fluorescence outputs. The complexity of this molecular logic network can greatly enhance the security level of this device.
Mathematical modeling of the extractables release from multi‐layered plastic films used in drug product containers
Authors: Jenke Dennis , Barge Vishal J. 
Published: July 2014

ABSTRACTThe release of extractables from multi‐layered plastic films such as those used in containers for liquid drug products has been investigated. Targeted extractables were chosen from the film's extractable profile, as elucidated by a controlled extraction study. The total available pool of targeted extractables was ascertained via exhaustive sequential extraction of the film and the film layer responsible for the target extractables was established. This information, along with the film's structure, was used to produce a mathematical migration model for each of these targets. The film was fashioned into pouches, filled with a simulating solvent and the release of the targeted extractables to the pouches' contents was measured. The measured and modeled concentrations were found to be very similar, establishing the model's ability to effectively mimic the experimental system. This result suggests that mathematical modeling, which is widely used in the food industry to assess the safety of food packaging, may be applicable to packaged pharmaceutical products. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41223.
Catalytic Glucose Isomerization by Porous Coordination Polymers with Open Metal Sites
Authors: Akiyama George , Matsuda Ryotaro , Sato Hiroshi , Kitagawa Susumu 
Published: July 2014

AbstractHighly efficient catalytic isomerization reactions from glucose to fructose in aqueous media using porous coordination polymers (PCPs) or metal–organic frameworks (MOFs) is reported for the first time. The catalytic activity of PCPs functionalized with NH2, (CH3)2, NO2, and SO3H groups on the pore surface is systematically tested. The catalytic activity can be tuned by the acidity of open metal sites (OMSs) by modifying the organic linkers with the functional groups. As a result, it is demonstrated that MIL‐101 functionalized with SO3H not only shows high conversion of glucose but also selectively produces fructose. Further, catalytic one‐pot conversion of amylose to fructose is achieved, thanks to the high stability of the framework in an acidic solution. These results show that MOF/PCP compounds having OMSs are promising materials for various useful heterogeneous catalytic reactions, in particular in the biomass field.
The association between lifetime smoking exposure and breast cancer mortality – results from a Norwegian cohort
Authors: Bjerkaas Eivind , Parajuli Ranjan , Engeland Anders , Maskarinec Gertraud , Weiderpass Elisabete , Gram Inger Torhild 
Published: July 2014

AbstractSeveral recent cohort studies have found an association between smoking and breast cancer, but the association between lifetime smoking exposure and breast cancer mortality is less well described. We examined whether smoking before breast cancer diagnosis is a predictor of breast cancer mortality in a large cohort with more than 4.1 million years of follow‐up, with a special focus on women who initiated smoking before first childbirth. Information on smoking status was collected before breast cancer diagnosis and used to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of breast cancer mortality in a cohort of 302,865 Norwegian women with 1106 breast cancer deaths. Women were enrolled between 1974 and 2003 and followed up through linkages to national registries until 31 December 2007. We found that breast cancer mortality was slightly but significantly increased for current (HR = 1.15, 95% CI 1.01–1.32) and ever (HR = 1.15, 95% CI 1.02–1.30) smokers as compared to never smokers. No statistically significantly increased mortality was found for women who initiated smoking before first childbirth, and no dose‐response association was revealed for any of the different measures of smoking exposure. A large proportion of heavy smokers may have died from other causes than breast cancer during follow‐up, possibly diluting our results. This study found that lifetime smoking exposure had a significantly increased risk of breast cancer mortality compared with never smokers.
Ionic Liquid and Sulfonic Acid Based Bifunctional Periodic Mesoporous Organosilica (BPMO–IL–SO3H) as a Highly Efficient and Reusable Nanocatalyst for the Biginelli Reaction
Authors: Elhamifar Dawood , Nasr‐Esfahani Masoud , Karimi Babak , Moshkelgosha Ramin , Shábani Ahmad 
Published: July 2014

AbstractThe catalytic application of a novel ionic liquid and sulfonic acid based bifunctional periodic mesoporous organosilica (BPMO–IL–SO3H) in the one‐pot Biginelli reaction was developed. The BPMO–IL–SO3H catalyst was first prepared by hydrolysis and co‐condensation of tetramethoxysilane, 1,3‐bis(trimethoxysilylpropyl)‐imidazolium iodide and 3‐mercaptopropyl‐trimethoxysilane in the presence of surfactant template under acidic conditions followed by oxidation of SH groups in the presence of hydrogen peroxide. This catalyst was then characterized by thermal gravimetric analysis, transmission electron microscopy, small‐angle powder X‐ray diffraction, and nitrogen sorption analysis. The performance of the BPMO–IL–SO3H catalyst was investigated in the Biginelli condensation of a variety of different aldehydes with alkylacetoacetates and urea under solvent‐free conditions. The catalyst exhibited excellent activity and delivered corresponding Biginelli products in high to excellent yields and selectivities. Moreover, the reactivity, reusability, and stability of the BPMO–IL–SO3H were also investigated under the applied reaction conditions. Our study showed that the catalyst could be recovered and reused at least 10 times without any significant decrease in efficiency.
Efficient Catalytic Hydrogenation of N‐Unsubstituted Cyclic Imides to Cyclic Amines
Authors: Maj Anna M. , Suisse Isabelle , Pinault Nathalie , Robert Nicolas , Agbossou‐Niedercorn Francine 
Published: July 2014

AbstractThe hydrogenation of N‐unsubstituted cyclic imides to the corresponding cyclic amines has been performed selectively with heterogeneous catalysts obtained from rhodium and molybdenum carbonyl precursors. Various substrates were reduced in good to high yields and selectivities. Platinum‐based catalysts also proved to be efficient. Furthermore, gram‐scale experiments were performed and the catalysts could be recycled.
Catalytic Deoxygenation of Fatty Acids: Elucidation of the Inhibition Process
Authors: Hollak Stefan A. W. , de Jong Krijn P. , van Es Daan S. 
Published: July 2014

AbstractCatalytic deoxygenation of unsaturated fatty acids in the absence of H2is known to suffer from significant catalyst inhibition. Thus far, no conclusive results have been reported on the cause of deactivation. Here we show that CC double bonds present in the feed or the products dramatically reduce the deoxygenation activity of supported palladium catalysts. In the case of stearic acid deoxygenation the addition of 0.1 equivalents of a mono‐unsaturated fatty acid or olefin already reduces the catalytic deoxygenation activity by 60 %. This effect becomes more pronounced with an increasing number of double bonds. The inhibition is shown to be reversible in H2atmosphere, indicating no significant contribution from irreversibly deposited hard coke. Furthermore, the type of support material has no apparent effect on catalyst inhibition. Hence we propose that initial catalyst inhibition proceeds through reversible adsorption of CC double bonds on the palladium active sites.
Corrosive Degeneration of Autoclaves for the Ammonothermal Synthesis: Experimental Approach and First Results
Authors: Hertweck Benjamin , Steigerwald Thomas G. , Alt Nicolas S. A. , Schluecker Eberhard 
Published: July 2014

AbstractThe ammonothermal growth of different bulk group III nitride materials enables cost‐efficient production of high‐quality single crystals. Despite its advantages this process is limited due to the corrosive ammonothermal environment. This environment consists of supercritical ammonia with acidic or basic additives at high temperatures and pressures in high‐pressure cells made of a nickel‐base alloy. As a consequence of corrosion, large amounts of metallic impurities are detectable in the grown crystals. The mechanisms of corrosion are not well understood. A method is presented to investigate corroded autoclaves, caused by the interaction with supercritical fluid, together with first results regarding the degeneration of autoclave material.
Combustion of Lithium Particles: Optical Measurement Methodology and Initial Results
Authors: Schiemann Martin , Fischer Peter , Scherer Viktor , Schmid Günter , Taroata Dan 
Published: July 2014

AbstractCombustion examinations on the single‐grain level were carried out in order to get further fundamental insight into the ignition and combustion of lithium particles. Combustion of solid lithium particles in a defined size fraction was analyzed in a laminar‐flow reactor. The exhaust gases of a methane‐air flame provided the reactants O2, CO2, N2, and H2O for the lithium conversion. Two different atmospheres at various temperatures were investigated. A high‐speed camera system measured size and radiation intensity of burning particles. The results indicate that two different combustion phenomena occurred in lithium combustion. The first was identified as a homogeneously enveloping flame around the lithium particle and the second as a reaction zone next to the particle surface.
Effect of Water Flow Rate on Decontamination Efficiency of Emergency Safety Showers
Authors: Brock Thomas , Heil Volker , Philipp Hermann , Seifert Ulrich , Steffens Wilfried , Timm Kurt 
Published: July 2014

AbstractStandards for overhead emergency safety showers used for decontamination in laboratories and production sites specify the spray pattern and the water flow rate. Up to now, there has not been a scientific basis for these requirements. The decontamination of water‐soluble contaminants has been investigated using 15 customary shower heads at different water flow rates. A general relationship between water flow rate and decontamination effectiveness could not be established: At a low flow rate, the wash‐off time in general did not exceed the time observed at considerably higher flow rates. The shortest decontamination time has been found with a spray pattern that does not fulfil current standards.
Toward a Consistent Interpretation of the QTAIM: Tortuous Link between Chemical Bonds, Interactions, and Bond/Line Paths
Authors: Foroutan‐Nejad Cina , Shahbazian Shant , Marek Radek 
Published: July 2014

AbstractCurrently, bonding analysis of molecules based on the Quantum Theory of Atoms in Molecules (QTAIM) is popular; however, “misinterpretations” of the QTAIM analysis are also very frequent. In this contribution the chemical relevance of the bond path as one of the key topological entities emerging from the QTAIM’s topological analysis of the one‐electron density is reconsidered. The role of nuclear vibrations on the topological analysis is investigated demonstrating that the bond paths are not indicators of chemical bonds. Also, it is argued that the detection of the bond paths is not necessary for the “interaction” to be present between two atoms in a molecule. The conceptual disentanglement of chemical bonds/interactions from the bonds paths, which are alternatively termed “line paths” in this contribution, dismisses many superficial inconsistencies. Such inconsistencies emerge from the presence/absence of the line paths in places of a molecule in which chemical intuition or alternative bonding analysis does not support the presence/absence of a chemical bond. Moreover, computational QTAIM studies have been performed on some “problematic” molecules, which were considered previously by other authors, and the role of nuclear vibrations on presence/absence of the line paths is studied demonstrating that a bonding pattern consistent with other theoretical schemes appears after a careful QTAIM analysis and a new “interpretation” of data is performed.
Self‐Assembly of Decoupled Borazines on Metal Surfaces: The Role of the Peripheral Groups
Authors: Kalashnyk Nataliya , Ganesh Nagaswaran Praveen , Kervyn Simon , Riello Massimo , Moreton Ben , Jones Tim S. , De Vita Alessandro , Bonifazi Davide , Costantini Giovanni 
Published: July 2014

AbstractTwo borazine derivatives have been synthesised to investigate their self‐assembly behaviour on Au(111) and Cu(111) surfaces by scanning tunnelling microscopy (STM) and theoretical simulations. Both borazines form extended 2D networks upon adsorption on both substrates at room temperature. Whereas the more compact triphenyl borazine 1 arranges into close‐packed ordered molecular islands with an extremely low density of defects on both substrates, the tris(phenyl‐4‐phenylethynyl) derivative 2 assembles into porous molecular networks due to its longer lateral substituents. For both species, the steric hindrance between the phenyl and mesityl substituents results in an effective decoupling of the central borazine core from the surface. For borazine 1, this is enough to weaken the molecule–substrate interaction, so that the assemblies are only driven by attractive van der Waals intermolecular forces. For the longer and more flexible borazine 2, a stronger molecule–substrate interaction becomes possible through its peripheral substituents on the more reactive copper surface.
One‐Pot Asymmetric Synthesis of Quaternary Pyrroloindolones through a Multicatalytic N‐Allylation/Hydroacylation Sequence
Authors: Lu Hong , Lin Jun‐Bing , Liu Jin‐Yu , Xu Peng‐Fei 
Published: July 2014

AbstractAn intramolecular, quaternary carbon center forming hydroacylation of α‐substituted acrylates has been discovered. This interesting transformation can be readily incorporated into a multicatalytic tandem process enabled by a combination of nucleophilic tertiary amine and N‐heterocyclic carbene catalysis. With no additional stoichiometric base required, this transformation affords the quaternary pyrroloindolones with high levels of enantioselectivity.
Anion Recognition with Hydrogen‐Bonding Cyclodiphosphazanes
Authors: Klare Helge , Hanft Sebastian , Neudörfl Jörg M. , Schlörer Nils E. , Griesbeck Axel , Goldfuss Bernd 
Published: July 2014

AbstractModular cyclodiphosph(V)azanes are synthesised and their affinity for chloride and actetate anions were compared to those of a bisaryl urea derivative (1). The diamidocyclodiphosph(V)azanes cis‐[{ArNHP(O)(μ‐tBu)}2] [Ar=Ph (2) and Ar=m‐(CF3)2Ph (3)] were synthesised by reaction of [{ClP(μ‐NtBu)}2] (4) with the respective anilines and subsequent oxidation with H2O2. Phosphazanes 2 and 3 were obtained as the cis isomers and were characterised by multinuclear NMR spectroscopy, FTIR spectroscopy, HRMS and single‐crystal X‐ray diffraction. The cyclodiphosphazanes 2 and 3 readily co‐crystallise with donor solvents such as MeOH, EtOH and DMSO through bidentate hydrogen bonding, as shown in the X‐ray analyses. Cyclodiphosphazane 3 showed a remarkably high affinity (log[K]=5.42) for chloride compared with the bisaryl urea derivative 1 (log[K]=4.25). The affinities for acetate (AcO−) are in the same range (3: log[K]=6.72, 1: log[K]=6.91). Cyclodiphosphazane 2, which does not contain CF3 groups, exhibits weaker binding to chloride (log[K]=3.95) and acetate (log[K]=4.49). DFT computations and X‐ray analyses indicate that a squaramide‐like hydrogen‐bond directionality and CαH interactions account for the efficiency of 3 as an anion receptor. The CαH groups stabilise the Z,Z‐3 conformation, which is necessary for bidentate hydrogen bonding, as well as coordinating with the anion.
Silyl Ligand Mediated Reversible β‐Hydrogen Elimination and Hydrometalation at Palladium
Authors: Takaya Jun , Iwasawa Nobuharu 
Published: July 2014

AbstractThe mechanism and origin of the facile β‐hydrogen elimination and hydrometalation of a palladium complex bearing a phenylene‐bridged PSiP pincer ligand are clarified. Experimental and theoretical studies demonstrate a new mechanism for β‐hydrogen elimination and hydrometalation mediated by a silyl ligand at palladium, which enables direct interconversion between an ethylpalladium(II) complex and an η2‐(Si‐H)palladium(0) complex without formation of a square‐planar palladium(II) hydride intermediate. The flexibility of the PSiP pincer ligand enables it to act as an efficient scaffold to deliver the hydrogen atom as a hydride ligand.
Gold(I)‐Catalysed Direct Thioetherifications Using Allylic Alcohols: an Experimental and Computational Study
Authors: Herkert Lorena , Green Samantha L. J. , Barker Graeme , Johnson David G. , Young Paul C. , Macgregor Stuart A. , Lee Ai‐Lan 
Published: July 2014

AbstractA gold(I)‐catalysed direct thioetherification reaction between allylic alcohols and thiols is presented. The reaction is generally highly regioselective (SN2′). This dehydrative allylation procedure is very mild and atom economical, producing only water as the by‐product and avoiding any unnecessary waste/steps associated with installing a leaving or activating group on the substrate. Computational studies are presented to gain insight into the mechanism of the reaction. Calculations indicate that the regioselectivity is under equilibrium control and is ultimately dictated by the thermodynamic stability of the products.
Dual Catalysis with Copper and Rhenium for Trifluoromethylation of Propargylic Alcohols: Efficient Synthesis of α‐Trifluoromethylated Enones
Authors: Egami Hiromichi , Ide Takafumi , Fujita Masashi , Tojo Toshifumi , Hamashima Yoshitaka , Sodeoka Mikiko 
Published: July 2014

AbstractTrifluoromethylation of propargylic alcohols to provide (Z)‐α‐trifluoromethylated enones and β‐unsubstituted α‐trifluoromethylated enones proceeded with high yield and selectivity in the presence of CuI/Re2O7. The Z isomer was formed under kinetic control, though it is less stable than the E isomer in terms of steric repulsion.
Volatile Times for the Very First Ionic Liquid: Understanding the Vapor Pressures and Enthalpies of Vaporization of Ethylammonium Nitrate
Authors: Emel'yanenko Vladimir N. , Boeck Gisela , Verevkin Sergey P. , Ludwig Ralf 
Published: July 2014

AbstractA hundred years ago, Paul Walden studied ethyl ammonium nitrate (EAN), which became the first widely known ionic liquid. Although EAN has been investigated extensively, some important issues still have not been addressed; they are now tackled in this communication. By combining experimental thermogravimetric analysis with time of flight mass spectrometry (TGA‐ToF‐MS) and transpiration method with theoretical methods, we clarify the volatilisation of EAN from ambient to elevated temperatures. It was observed that up to 419 K, EAN evaporates as contact‐ion pairs leading to very low vapour pressures of a few Pascal. Starting from 419 K, the decomposition to nitric acid and ethylamine becomes more thermodynamically favourable than proton transfer. This finding was supported by DFT calculations, which provide the free energies of all possible gas‐phase species, and show that neutral molecules dominate over ion pairs above 500 K, an observation that is in nearly prefect agreement with the experimental boiling point of 513 K. This result is crucial for the ongoing practical applications of protic ionic liquids such as electrolytes for batteries and fuel cells because, in contrast to high‐boiling conventional solvents, EAN exhibits no significant vapour pressure below 419 K and this property fulfils the requirements for the thermal behaviour of safe electrolytes. Overall, EAN shows the same barely measurable vapour pressures as typical aprotic ionic liquids at temperatures only 70 K lower.