bluuebunny/crossref_metadata_2025_split huggingface dataset:
C‐Alkylierung von Ketonen und verwandten Verbindungen durch Alkohole: übergangsmetallkatalysierte Dehydrierung
Authors: Huang Fei , Liu Zhuqing , Yu Zhengkun 
Published: December 2015

AbstractDie übergangsmetallkatalysierte C‐Alkylierung von Ketonen und sekundären Alkoholen mit Alkoholen umgeht den Einsatz von metallorganischen oder umweltschädlichen Alkylierungsreagentien über die Borrowing‐Hydrogen(BH)‐ oder Hydrogen‐Autotransfer(HA)‐Aktivierung der Alkoholsubstrate. Da Wasser als einziges Begleitprodukt entsteht, ist das BH‐Verfahren atomökonomisch und umweltfreundlich. Viele homogene und heterogene Übergangsmetallkatalysatoren, Ketone und Alkohole sind in dieser Reaktion einsetzbar, sodass das BH‐Verfahren aussichtsreich scheint, die derzeitigen Verfahren zu ersetzen, die herkömmliche Alkylierungsreagentien verwenden. Dieser Kurzaufsatz fasst die Fortschritte in der übergangsmetallkatalysierten α‐Alkylierung von Ketonen und β‐Alkylierung von sekundären Alkoholen mit Alkoholen mithilfe der BH‐Technik während der letzten fünf Jahre zusammen. Auch die Eignung der BH‐Strategie zur C‐C‐Bindungsbildung wird diskutiert.
Spectra Library: An Assumption‐Free In Situ Method to Access the Kinetics of Catechols Binding to Colloidal ZnO Quantum Dots
Authors: Lin Wei , Haderlein Michael , Walter Johannes , Peukert Wolfgang , Segets Doris 
Published: December 2015

AbstractAssumption‐free and in situ resolving of the kinetics of ligand binding to colloidal nanoparticles (NPs) with high time resolution is still a challenge in NP research. A unique concept of using spectra library and stopped‐flow together with a “search best‐match” Matlab algorithm to access the kinetics of ligand binding in colloidal systems is reported. Instead of deconvoluting superimposed spectra using assumptions, species absorbance contributions (ligand@ZnO NPs and ligand in solution) are obtained by offline experiments. Therefrom, a library of well‐defined targets with known ligand distribution between particle surface and solution is created. Finally, the evolution of bound ligand is derived by comparing in situ spectra recorded by stopped‐flow and the library spectra with the algorithm. Our concept is a widely applicable strategy for kinetic studies of ligand adsorption to colloidal NPs and a big step towards deep understanding of surface functionalization kinetics.
Light‐Induced Reversible Self‐Assembly of Gold Nanoparticles Surface‐Immobilized with Coumarin Ligands
Authors: He Huibin , Feng Miao , Chen Qidi , Zhang Xinqi , Zhan Hongbing 
Published: December 2015

AbstractA novel light‐induced reversible self‐assembly (LIRSA) system is based on the reversible photodimerization and photocleavage of coumarin groups on the surface of gold nanoparticles (AuNPs) in THF solution. Facilitated by coumarin groups, light irradiation at 365 nm triggers the stable assembly of monodisperse AuNPs; the resulting self‐assembly system can be disassembled back to the disassembled state by a relatively short exposure to benign UV light. The reversible self‐assembly cycle can be repeated 4 times. A specific concentration range of coumarin ligand and the THF solvent were identified to be the two predominant factors that contribute to the LIRSA of AuNPs. This is the first successful application of reversible photodimerization based on a coumarin derivative in the field of AuNP LIRSA. This LIRSA system may provide unique opportunities for the photoregulated synthesis of many adjustable nanostructures and devices.
Asymmetric Allylic Alkylation of β‐Ketoesters with Allylic Alcohols by a Nickel/Diphosphine Catalyst
Authors: Kita Yusuke , Kavthe Rahul D. , Oda Hiroaki , Mashima Kazushi 
Published: December 2015

AbstractAsymmetric allylic alkylation of β‐ketoesters with allylic alcohols catalyzed by [Ni(cod)2]/(S)‐H8‐BINAP was found to be a superior synthetic protocol for constructing quaternary chiral centers at the α‐position of β‐ketoesters. The reaction proceeded in high yield and with high enantioselectivity using various β‐ketoesters and allylic alcohols, without any additional activators. The versatility of this methodology for accessing useful and enantioenriched products was demonstrated.
Universelle Methode zur Herstellung von Aerogelen aus kolloidalen Nanopartikellösungen durch Einfrieren und anschließendes Gefriertrocknen
Authors: Freytag Axel , Sánchez‐Paradinas Sara , Naskar Suraj , Wendt Natalja , Colombo Massimo , Pugliese Giammarino , Poppe Jan , Demirci Cansunur , Kretschmer Imme , Bahnemann Detlef W. , Behrens Peter , Bigall Nadja C. 
Published: December 2015

AbstractIn dieser Zuschrift wird über eine universelle Methode zur Herstellung von selbsttragenden Aerogelen aus kolloidalen Nanopartikeln (NP) berichtet. Dafür werden die NP eingefroren und anschließend gefriergetrocknet. Das bedeutet, dass die kolloidalen NP ohne vorherige Gelierung (wie bisher bei herkömmlichen Aero‐ und Kryogel‐Verfahren üblich) direkt in trockene, aerogelähnliche monolithische Überstrukturen überführt werden können. Die Anordnung der NP zu einer Überstruktur ist ein rein physikalischer Prozess und dadurch vielfältig einsetzbar, was bedeutet, dass die Kryogelierung auf Edelmetall‐, Metalloxid‐ und Halbleiter‐NP angewendet werden kann. Die Kryogelierung beeinflusst die Oberflächenchemie oder die NP‐Form in der entstehenden Morphologie dabei nicht. Unter idealen Bedingungen sind auch die Volumina und die Formen von gefrorenem NP‐Kolloid und Aerogel gleich groß. Dies ermöglicht es, mit der Methode dünne, gleichmäßige Aerogelfilme und andere Geometrien von Aerogelmonolithen herzustellen. Abschließend werden die physikochemischen Eigenschaften der Aerogele diskutiert.
Dynamic Coupling at the Ångström Scale
Authors: Dey Krishna Kanti , Pong Frances Ying , Breffke Jens , Pavlick Ryan , Hatzakis Emmanuel , Pacheco Carlos , Sen Ayusman 
Published: December 2015

AbstractWhile momentum transfer from active particles to their immediate surroundings has been studied for both synthetic and biological micron‐scale systems, a similar phenomenon was presumed unlikely to exist at smaller length scales due to the dominance of viscosity in the ultralow Reynolds number regime. Using diffusion NMR spectroscopy, we studied the motion of two passive tracers—tetramethylsilane and benzene—dissolved in an organic solution of active Grubbs catalyst. Significant enhancements in diffusion were observed for both the tracers and the catalyst as a function of reaction rate. A similar behavior was also observed for the enzyme urease in aqueous solution. Surprisingly, momentum transfer at the molecular scale closely resembles that reported for microscale systems and appears to be independent of swimming mechanism. Our work provides new insight into the role of active particles on advection and mixing at the Ångström scale.
Chemical Synthesis of Proteins with Non‐Strategically Placed Cysteines Using Selenazolidine and Selective Deselenization
Authors: Reddy Post Sai , Dery Shahar , Metanis Norman 
Published: December 2015

AbstractAlthough native chemical ligation has enabled the synthesis of hundreds of proteins, not all proteins are accessible through typical ligation conditions. The challenging protein, 125‐residue human phosphohistidine phosphatase 1 (PHPT1), has three cysteines near the C‐terminus, which are not strategically placed for ligation. Herein, we report the first sequential native chemical ligation/deselenization reaction. PHPT1 was prepared from three unprotected peptide segments using two ligation reactions at cysteine and alanine junctions. Selenazolidine was utilized as a masked precursor for N‐terminal selenocysteine in the middle segment, and, following ligation, deselenization provided the native alanine residue. This approach was used to synthesize both the wild‐type PHPT1 and an analogue in which the active‐site histidine was substituted with the unnatural and isosteric amino acid β‐thienyl‐l‐alanine. The activity of both proteins was studied and compared, providing insights into the enzyme active site.
The Origin of the Reactivity of the Criegee Intermediate: Implications for Atmospheric Particle Growth
Authors: Miliordos Evangelos , Xantheas Sotiris S. 
Published: December 2015

AbstractThe electronic structure of the simplest Criegee intermediate, H2COO, is practically that of a closed shell. On the biradical scale (β), where 0 corresponds to the pure closed shell and 1 to a pure biradical, its β value is only 0.10, suggesting that its ground electronic state is best described as a H2C=Oδ+−Oδ− zwitterion. However, this picture of a nearly inert closed shell contradicts its rich reactivity in the atmosphere. It is shown that the mixing of its ground state with the first triplet excited state, which is a pure biradical state of the type H2C.−O−O., is responsible for the formation of strongly bound products during reactions inducing atmospheric particle growth.
[3,3]‐Sigmatropic Rearrangement/Allylboration/Cyclization Sequence: Enantioenriched Seven‐Membered‐Ring Carbamates and Ring Contraction to Pyrrolidines
Authors: Macé Aurélie , Touchet Sabrina , Andres Patricia , Cossío Fernando , Dorcet Vincent , Carreaux François , Carboni Bertrand 
Published: December 2015

AbstractThe combination of in situ generated α‐isocyanato allylboronic esters and aldehydes afforded seven‐membered‐ring enecarbamates with high levels of diastereo‐ and enantiocontrol. They were easily converted into diversely substituted 1,3‐oxazepan‐2‐ones. An unprecedented rearrangement of 5‐acetoxy‐7‐aryl or styryl derivatives led to tetrasubstituted pyrrolidines. A computational study provides evidence on the feasibility of the proposed mechanism of this unusual ring contraction.
Complementary Iron(II)‐Catalyzed Oxidative Transformations of Allenes with Different Oxidants
Authors: Sabbasani Venkata R. , Lee Hyunjin , Xia Yuanzhi , Lee Daesung 
Published: December 2015

AbstractSubstituent‐ and oxidant‐dependent transformations of allenes are described. Given the profound influence of the substituent on the reactivity of allenes, the subtle differences in allene structures are manifested in the formation of diverse products when reacted with different electrophiles/oxidants. In general, reactions of nonsilylated allenes involve an allylic cation intermediate by forming a C−O bond, at the sp‐hybridized C2, with either DDQ (2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone) or TBHP (tert‐butyl hydroperoxide), along with FeCl2⋅4 H2O (10 mol %). In contrast, silylated allenes favor the formation of propargylic cation intermediates by transferring the allenic hydride to the oxidant, thus generating 1,3‐enynes (E1 product) or propargylic THBP ethers (SN1 product). The formation of these different putative cationic intermediates from nonsilylated and silylated allenes is strongly supported by DFT calculations.
Versatile Aerogel Fabrication by Freezing and Subsequent Freeze‐Drying of Colloidal Nanoparticle Solutions
Authors: Freytag Axel , Sánchez‐Paradinas Sara , Naskar Suraj , Wendt Natalja , Colombo Massimo , Pugliese Giammarino , Poppe Jan , Demirci Cansunur , Kretschmer Imme , Bahnemann Detlef W. , Behrens Peter , Bigall Nadja C. 
Published: December 2015

AbstractA versatile method to fabricate self‐supported aerogels of nanoparticle (NP) building blocks is presented. This approach is based on freezing colloidal NPs and subsequent freeze drying. This means that the colloidal NPs are directly transferred into dry aerogel‐like monolithic superstructures without previous lyogelation as would be the case for conventional aerogel and cryogel fabrication methods. The assembly process, based on a physical concept, is highly versatile: cryogelation is applicable for noble metal, metal oxide, and semiconductor NPs, and no impact of the surface chemistry or NP shape on the resulting morphology is observed. Under optimized conditions the shape and volume of the liquid equal those of the resulting aerogels. Also, we show that thin and homogeneous films of the material can be obtained. Furthermore, the physical properties of the aerogels are discussed.
Flexible Hierarchical TiO2/Fe2O3 Composite Membrane with High Separation Efficiency for Surfactant‐Stabilized Oil‐Water Emulsions
Authors: Tan Benny Yong Liang , Juay Jermyn , Liu Zhaoyang , Sun Darren 
Published: December 2015

AbstractGlobally, efficient oil‐water separation for surfactant‐stabilized oil‐water emulsions has been in urgent demand. The current options available for separation are neither sustainable nor resistant to fouling. Herein, we introduce a hierarchically nanostructured TiO2/Fe2O3 composite membrane, which is capable of separating surfactant‐stabilized oil‐water emulsions with high separation efficiency. The high oil rejection rate is contributed by the acquisition of an interconnected delicate network and underwater superoleophobic interface. Meanwhile, its self‐cleaning function promote the facile recovery of the contaminated membrane. Furthermore, the mechanical flexible characteristic of the TiO2/Fe2O3 composite membrane widens its applicability in industrial employment. Thanks to these properties, this novel membrane can be considered as a practical option for treating surfactant‐stabilized oil‐water emulsions.
Polystyrene‐Core–Silica‐Shell Hybrid Particles Containing Gold and Magnetic Nanoparticles
Authors: Tian Jia , Vana Philipp 
Published: December 2015

AbstractPolystyrene‐core–silica‐shell hybrid particles were synthesized by combining the self‐assembly of nanoparticles and the polymer with a silica coating strategy. The core–shell hybrid particles are composed of gold‐nanoparticle‐decorated polystyrene (PS‐AuNP) colloids as the core and silica particles as the shell. PS‐AuNP colloids were generated by the self‐assembly of the PS‐grafted AuNPs. The silica coating improved the thermal stability and dispersibility of the AuNPs. By removing the “free” PS of the core, hollow particles with a hydrophobic cage having a AuNP corona and an inert silica shell were obtained. Also, Fe3O4 nanoparticles were encapsulated in the core, which resulted in magnetic core–shell hybrid particles by the same strategy. These particles have potential applications in biomolecular separation and high‐temperature catalysis and as nanoreactors.
High throughput chromatography strategies for potential use in the formal process characterization of a monoclonal antibody
Authors: Petroff Matthew G. , Bao Haiying , Welsh John P. , van Beuningen – de Vaan Miranda , Pollard Jennifer M. , Roush David J. , Kandula Sunitha , Machielsen Peter , Tugcu Nihal , Linden Thomas O. 
Published: December 2015

ABSTRACTHigh throughput experimental strategies are central to the rapid optimization of biologics purification processes. In this work, we extend common high throughput technologies towards the characterization of a multi‐column chromatography process for a monoclonal antibody (mAb). Scale‐down strategies were first evaluated by comparing breakthrough, retention, and performance (yields and clearance of aggregates and host cell protein) across miniature and lab scale columns. The process operating space was then evaluated using several integrated formats, with batch experimentation to define process testing ranges, miniature columns to evaluate the operating space, and comparison to traditional scale columns to establish scale‐up correlations and verify the determined operating space. When compared to an independent characterization study at traditional lab column scale, the high throughput approach identified the same control parameters and similar process sensitivity. Importantly, the high throughput approach significantly decreased time and material needs while improving prediction robustness. Miniature columns and manufacturing scale centerpoint data comparisons support the validity of this approach, making the high throughput strategy an attractive and appropriate scale‐down tool for the formal characterization of biotherapeutic processes in the future if regulatory acceptance of the miniature column data can be achieved. Biotechnol. Bioeng. 2016;113: 1273–1283. © 2015 Wiley Periodicals, Inc.
Metal–Ligand Misfits: Facile Access to Rhenium–Oxo Corroles by Oxidative Metalation
Authors: Einrem Rune F. , Gagnon Kevin J. , Alemayehu Abraham B. , Ghosh Abhik 
Published: December 2015

AbstractWith the exception of a single accidental synthesis, rhenium corroles are unknown, but of great interest as catalysts and potential radiopharmaceuticals. Oxidative metalation of meso‐triarylcorroles with [Re2(CO)10] in refluxing decalin has provided a facile and relatively high‐yielding route to rhenium(V)–oxo corroles. The complexes synthesized could all be fully characterized by single‐crystal X‐ray structure analyses.
Oxydifluoromethylation of Alkenes by Photoredox Catalysis: Simple Synthesis of CF2H‐Containing Alcohols
Authors: Arai Yusuke , Tomita Ren , Ando Gaku , Koike Takashi , Akita Munetaka 
Published: December 2015

AbstractWe have developed a novel and simple protocol for the direct incorporation of a difluoromethyl (CF2H) group into alkenes by visible‐light‐driven photoredox catalysis. The use of fac‐[Ir(ppy)3] (ppy=2‐pyridylphenyl) photocatalyst and shelf‐stable Hu's reagent, N‐tosyl‐S‐difluoromethyl‐S‐phenylsulfoximine, as a CF2H source is the key to success. The well‐designed photoredox system achieves synthesis of not only β‐CF2H‐substituted alcohols but also ethers and an ester from alkenes through solvolytic processes. The present method allows a single‐step and regioselective formation of C(sp3)–CF2H and C(sp3)−O bonds from C=C moiety in alkenes, such as hydroxydifluoromethylation, regardless of terminal or internal alkenes. Moreover, this methodology tolerates a variety of functional groups.
Effects of Fostamatinib on the Pharmacokinetics of the CYP2C8 Substrate Pioglitazone: Results From In Vitro and Phase 1 Clinical Studies
Authors: Martin Paul , Gillen Michael , Millson David , Oliver Stuart , Brealey Clive , Surry Dominic , Sweeny David , Lau David , Leese Philip 
Published: December 2015

AbstractFostamatinib is a prodrug that undergoes gastrointestinal tract dephosphorylation to form the active metabolite, R406. Here we report its cytochrome P450–inducing potential. In vitro, R406 3 and 10 μM induced CYP2C8 to levels representing 53% and 75%, respectively, of the level achieved by the positive control, rifampicin. Induction of other enzymes was minor. The effect of fostamatinib (100 mg twice daily) on the pharmacokinetics of a single oral 30‐mg dose of the CYP2C8 substrate pioglitazone and its metabolite, hydroxy pioglitazone, was then investigated (open‐label, nonrandomized, 2‐period phase I study [n = 15]). Coadministration of fostamatinib and pioglitazone (vs pioglitazone alone) was associated with lower mean maximum plasma concentration values for pioglitazone (geometric least‐squares mean ratio, 82.8; 90% confidence interval, 64.2–106.8) and hydroxy pioglitazone (90.9; 78.6–105.1), an increase in pioglitazone AUC (117.8; 108.4–128.0), a decrease in hydroxy pioglitazone AUC(0–t) (89.7; 78.9–101.9), and an increase in pioglitazone geometric mean t1/2λz (9.4–12.8 hours). No tolerability concerns were identified upon coadministration. These data suggest that although clinical significance has not been formally evaluated, fostamatinib is unlikely to have a clinically significant effect on the pharmacokinetics of pioglitazone (which may be extrapolated to other CYP2C8 substrates). However, vigilance is advised should these agents be prescribed together.
Pharmacokinetics, Safety, and Tolerability of Fevipiprant (QAW039), a Novel CRTh2 Receptor Antagonist: Results From 2 Randomized, Phase 1, Placebo‐Controlled Studies in Healthy Volunteers
Authors: Erpenbeck Veit J. , Vets Eva , Gheyle Lien , Osuntokun Wande , Larbig Michael , Neelakantham Srikanth , Sandham David , Dubois Gerald , Elbast Walid , Goldsmith Paul , Weiss Markus 
Published: December 2015

AbstractWe evaluated the pharmacokinetics (PK), safety, and tolerability of a novel oral CRTh2 antagonist, fevipiprant (QAW039), in healthy subjects. Peak concentrations of fevipiprant in plasma were observed 1‒3 hours postdosing. Concentrations declined in a multiexponential manner, followed by an apparent terminal phase (t1/2, ∼20 hours). Steady state was achieved in 4 days with <2‐fold accumulation. Elimination was partly by renal excretion (≤30% of the dose) and glucuronidation. Food had minimal impact on the PK of fevipiprant, and it was well tolerated at single and multiple oral doses up to 500 mg/day. No dose‐dependent adverse events were observed, and all the events were mild or moderate in severity. Systemic concentrations were sufficiently high to achieve relevant target occupancy, considering in vitro pharmacology data. In summary, the data support further development as a once‐daily oral therapy for allergic diseases.
Strategies for the Controlled Electronic Doping of Colloidal Quantum Dot Solids
Authors: Stavrinadis Alexandros , Konstantatos Gerasimos 
Published: December 2015

AbstractOver the last several years tremendous progress has been made in incorporating colloidal quantum dot (CQD) solids as photoactive components in optoelectronic devices. A large part of this progress is associated with significant advancements made in controlling the electronic doping of CQD solids. Today, a variety of strategies exists towards that purpose; this Minireview aims to survey the major published works in this subject. Additional attention is given to the many challenges associated with the task of doping CQDs, as well as to the realization of optoelectronic functionalities and applications upon successful light and heavy electronic doping of CQD solids.
Properties of Apolar Solutes in Alkyl Imidazolium‐Based Ionic Liquids: The Importance of Local Interactions
Authors: Lesch Volker , Heuer Andreas , Holm Christian , Smiatek Jens 
Published: December 2015

AbstractThe solvation and the dynamic properties of apolar model solutes in alkyl imidazolium‐based ionic liquids (IL) are studied by using all‐atom molecular dynamics simulations. In regards to specific IL effects, we focused on the often used 1‐ethyl‐3‐methyl imidazolium cation in combination with the anions tetrafluoroborate, acetate, and bis(trifluoromethanesulfonyl)imide. Our findings reveal that the size of the anion crucially influences the accumulation behavior of the cations, which results in modified IL solvation properties. Deviations between the different alkyl imidazolium‐based IL combinations can be also observed with regard to the results for the radial distribution functions, the number of surrounding molecules, and the molecular orientation. The analysis of the van Hove function further shows pronounced differences in the dynamic behavior of the solutes. The simulations verify that the solute mobilities are mainly influenced by the composition of the local solvent shell and the properties of the underlying Lennard–Jones interactions. Additional simulations with regard to modified short‐range dispersion energies for alkyl imidazolium‐based ILs validate our conclusions.