bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bifunctional Behavior of Unsaturated Intramolecular Phosphane–Borane Frustrated Lewis Pairs Derived from Uncatalyzed 1,4‐Hydrophosphination of a Dienylborane
Authors: Chen Guo‐Qiang , Kehr Gerald , Daniliuc Constantin G. , Wibbeling Birgit , Erker Gerhard 
Published: July 2015

AbstractThree unsaturated C4‐bridged phospane/borane frustrated Lewis pairs (P/B FLPs) are prepared by uncatalyzed hydrophosphination of a dienylborane. The systems are bifunctional. Consequently, two examples undergo clean hydroboration reactions with HB(C6F5)2 to yield B/B/P systems. The 1,4‐P/B system (C6F5)2BCH2CHCMeCH2PMes2 reacts with benzaldehyde initially by allylborane addition, followed by internal P/B FLP addition to the pendant CC double bond, to yield a bicyclic product. The corresponding reaction of (C6F5)2BCH2CHCMeCH2PtBu2 stops at the allylborane/benzaldehyde addition product. The related system (C6F5)2BCH2CHCMeCH2PPh2 shows a similar bifunctional reaction pattern, whereby allylborane addition to benzaldehyde is combined with P/B addition to a second aldehyde equivalent to form the eight‐membered heterocyclic 1:2 addition product.
Structure Evolution and Associated Catalytic Properties of PtSn Bimetallic Nanoparticles
Authors: Rong Hongpan , Niu Zhiqiang , Zhao Yafan , Cheng Hao , Li Zhi , Ma Lei , Li Jun , Wei Shiqiang , Li Yadong 
Published: July 2015

AbstractBimetallic nanoparticles (NPs) often show new catalytic properties that are different from those of the parent metals. Carefully exploring the structures of bimetallic NPs is a prerequisite for understanding the structure‐associated properties. Herein, binary PtSn NPs with tunable composition are prepared in a controllable manner. X‐ray characterizations reveal that their structures evolve from SnO2−x‐patched PtSn alloys to SnO2−x‐patched Pt clusters when more tin is incorporated. An obvious composition‐dependent catalytic performance is observed for the hydrogenation of α,β‐unsaturated aldehydes: the selectivity to unsaturated alcohol increases substantially at high tin content, whereas the reaction rate follows a volcano shape. Furthermore, Pt sites are responsible for hydrogen dissociation, whereas oxygen vacancy (Ovac) sites, provided by SnO2−x, drastically enhance the adsorption of carbonyl group.
Hydroxymethylated Dioxobilins in Senescent Arabidopsis thaliana Leaves: Sign of a Puzzling Biosynthetic Intermezzo of Chlorophyll Breakdown
Authors: Süssenbacher Iris , Kreutz Christoph R. , Christ Bastien , Hörtensteiner Stefan , Kräutler Bernhard 
Published: July 2015

Abstract1‐Formyl‐19‐oxobilin‐type tetrapyrroles are characteristic, abundant products of chlorophyll breakdown in senescent leaves. However, in some leaves, 1,19‐dioxobilin‐type chlorophyll catabolites (DCCs) lacking the formyl group accumulate instead. A P450 enzyme was identified in in vitro studies that removed the formyl group of a primary fluorescent chlorophyll catabolite (pFCC) and generated fluorescent DCCs. These DCCs are precursors of isomeric nonfluorescent DCCs (NDCCs). Here, we report a structural investigation of the NDCCs in senescent leaves of wild‐type Arabidopsis thaliana. Four new NDCCs were characterized, two of which carried a stereoselectively added hydroxymethyl group. Such formal DCC hydroxymethylations were previously found in DCCs in leaves of a mutant of A. thaliana. They are now indicated to be a feature of chlorophyll breakdown in A. thaliana, associated with the specific in vivo deformylation of pFCC en route to NDCCs.
Are Copper(I) Carbenes Capable Intermediates for Cyclopropanations? The Case for Ylide Intermediates
Authors: Aldajaei Jamal T. , Keeffe James R. , Swift Christopher A. , Gronert Scott 
Published: July 2015

AbstractA novel approach is used to synthesize a stable, ligated copper(I) carbene in the gas phase that is capable of typical metal carbenoid chemistry. However, it is shown that copper(I) carbenes generally undergo rapid unimolecular rearrangements including insertions into copper‐ligand bonds and Wolff rearrangements. The results indicate that most copper(I) carbenes are inherently unstable and would not be viable intermediates in condensed‐phase applications; an alternative intermediate that is less prone to rearrangements is required. Computational data suggest that ylides formed by the complexation of the carbene with solvent or other weak nucleophiles are viable intermediates in the reactions of copper(I) carbenes.
Chemical Synthesis of a Glycopeptide Derived from Skp1 for Probing Protein Specific Glycosylation
Authors: Chinoy Zoeisha S. , Schafer Christopher M. , West Christopher M. , Boons Geert‐Jan 
Published: July 2015

AbstractSkp1 is a cytoplasmic and nuclear protein, best known as an adaptor of the SCF family of E3‐ubiquitin ligases that label proteins for their degradation. Skp1 in Dictyostelium is posttranslationally modified on a specific hydroxyproline (Hyp) residue by a pentasaccharide, which consists of a Fucα1,2‐Galβ‐1,3‐GlcNAcα core, decorated with two α‐linked Gal residues. A glycopeptide derived form Skp1 was prepared to characterize the α‐galactosyltransferase (AgtA) that mediates the addition of the α‐Gal moieties, and to develop antibodies suitable for tracking the trisaccharide isoform of Skp1 in cells. A strategy was developed for the synthesis of the core trisaccharide‐Hyp based on the use of 2‐naphthylmethyl (Nap) ethers as permanent protecting groups to allow late stage installation of the Hyp moiety. Tuning of glycosyl donor and acceptor reactivities was critical for achieving high yields and anomeric selectivities of glycosylations. The trisaccharide‐Hyp moiety was employed for the preparation of the glycopeptide using microwave‐assisted solid phase peptide synthesis. Enzyme kinetic studies revealed that trisaccharide‐Hyp and trisaccharide‐peptide are poorly recognized by AgtA, indicating the importance of context provided by the native Skp1 protein for engagement with the active site. The trisaccharide‐peptide was a potent immunogen capable of generating a rabbit antiserum that was highly selective toward the trisaccharide isoform of full‐length Skp1.
Sequential Synthesis of 3 d–3 d, 3 d–4 d, and 3 d–5 d Hybrid Polyoxometalates and Application to the Electrocatalytic Oxygen Reduction Reactions
Authors: Rousseau Guillaume , Zhang Shuangshuang , Oms Olivier , Dolbecq Anne , Marrot Jérôme , Liu Rongji , Shang Xinke , Zhang Guangjin , Keita Bineta , Mialane Pierre 
Published: July 2015

AbstractThe Co7(AlePy)2 polyoxometalate, which encloses a {(PW9)2CoII7} core covalently bound to two free aminopyridine groups through bisphosphonate ligands (AlePy), has been isolated. It can be used as a precursor, allowing the synthesis of heterometallic hybrid compounds, as illustrated by the characterization of cobalt/zinc (Co7(AlePyZn)2), cobalt/palladium (Co7(AlePyPd)2), and cobalt/platinum (Co7(AlePyPt)2) species. A composite based on the water‐insoluble precious metal‐free Co7(AlePyZn)2 compound and the low‐cost carbon material Vulcan XC‐72 has been selected as a cathode material (Co7Zn/C) for oxygen reduction reaction studies. The electrocatalytic performances of the Co7Zn/C hybrids were assessed at neutral and basic pH, showing that Co7Zn/C exhibits high selectivity for the four‐electron reduction of O2. Moreover, its durability is superior to that of a commercial Pt/C catalyst with 20 % loading. Also, comparative studies performed in the presence of methanol have indicated that Co7Zn/C has a much better tolerance to the crossover effect than Pt/C. Altogether, these results indicate for the first time that, even in neutral media, polyoxometalate/carbon composites can represent low‐cost oxygen reduction catalysts that can function stably, for a long time, and with high performance.
Host–Guest‐Mediated DNA Templation of Polycationic Supramolecules for Hierarchical Nanocondensation and the Delivery of Gene Material
Authors: Gallego‐Yerga Laura , Blanco‐Fernández Laura , Urbiola Koldo , Carmona Thais , Marcelo Gema , Benito Juan M. , Mendicuti Francisco , Tros de Ilarduya Conchita , Ortiz Mellet Carmen , García Fernández José M. 
Published: July 2015

AbstractOnly a few examples of monodisperse molecular entities that can compact exogenous nucleic acids into nanocomplexes, protect the cargo from the biological environment, facilitate cell internalization, and promote safe transfection have been reported up to date. Although these species open new venues for fundamental studies on the structural requirements that govern the intervening processes and their application in nonviral gene‐vector design, the synthesis of these moieties generally requires a relatively sophisticated chemistry, which hampers further development in gene therapy. Herein, we report an original strategy for the reversible complexation and delivery of DNA based on the supramolecular preorganization of a β‐cyclodextrin‐scaffolded polycationic cluster facilitated by bisadamantane guests. The resulting gemini‐type, dual‐cluster supramolecules can then undergo DNA‐templated self‐assembly at neutral pH value by bridging parallel DNA oligonucleotide fragments. This hierarchical DNA condensation mechanism affords transfectious nanoparticles with buffering capabilities, thus facilitating endosomal escape following cell internalization. Protonation also destabilizes the supramolecular dimers and consequently the whole supramolecular edifice, thus assisting DNA release. Our advanced hypotheses are supported by isothermal titration calorimetry, NMR and circular dichroism spectroscopic analysis, gel electrophoresis, dynamic light scattering, TEM, molecular mechanics, molecular dynamics, and transfection studies conducted in vitro and in vivo.
Synthesis of New Phosphahelicene Scaffolds and Development of Gold(I)‐Catalyzed Enantioselective Allenene Cyclizations
Authors: Aillard Paul , Retailleau Pascal , Voituriez Arnaud , Marinetti Angela 
Published: July 2015

AbstractThis paper reports on the development of an efficient synthesis of enantiopure phospha[6]helicenes through a [2+2+2] alkyne cyclotrimerization reaction. The corresponding gold complexes proved to be highly efficient both in terms of catalytic activity and enantioselectivity in [2+2] and [4+2] cycloaddition reactions. Furthermore, in the presence of an external nucleophile, such as water or alcohols, the tandem cyclization/addition reactions take place in high yields and excellent diastereo‐ and enantioselectivities.
Metal‐Chelating N,N′‐Bis(4‐dimethylaminophenyl)acetamidinyl Radical: A New Chromophore for the Near‐Infrared Region
Authors: Ehret Fabian , Bubrin Martina , Záliš Stanislav , Kaim Wolfgang 
Published: July 2015

AbstractA new non‐innocent ligand redox system, N,N′‐bis(4‐dimethylaminophenyl) substituted acetamidinato/acetamidinyl, has been designed and described by example of structurally and spectroscopically characterized ruthenium complexes. The hitherto unreported ligand is responsible for rather intense and narrow absorptions in the near‐infrared region of the one‐ and two‐electron oxidized forms. The spectroscopic, computational, and first structural characterization of an amidinyl radical complex adds to the list of established N‐based radical ligands.
A Stable Seven‐Membered Heterocycle, Containing B, C, N, O, and P Atoms, inside a Smaragdyrin Macrocycle
Authors: Kalita Hemanta , Lee Way‐Zen , Theophall Gregory G. , Lakshmi K. V. , Ravikanth M. 
Published: July 2015

AbstractUnprecedented examples of smaragdyrin macrocycles containing seven membered heterocyclic rings were synthesized under simple reaction conditions in high yields. The heterocycle formed inside smaragdyrin macrocycle is rare example of heterocycle containing five different atoms, such as B, C, N, O, and P atoms. The mixed BIII and PV complexes of smaragdyrin macrocycles showed new structural, spectral, and electrochemical properties.
Dynamic Covalent Organocatalysts Discovered from Catalytic Systems through Rapid Deconvolution Screening
Authors: Schaufelberger Fredrik , Ramström Olof 
Published: July 2015

AbstractThe first example of a bifunctional organocatalyst assembled through dynamic covalent chemistry (DCC) is described. The catalyst is based on reversible imine chemistry and can catalyze the Morita–Baylis–Hillman (MBH) reaction of enones with aldehydes or N‐tosyl imines. Furthermore, these dynamic catalysts were shown to be optimizable through a systemic screening approach, in which large mixtures of catalyst structures were generated, and the optimal catalyst could be directly identified by using dynamic deconvolution. This strategy allowed one‐pot synthesis and in situ evaluation of several potential catalysts without the need to separate, characterize, and purify each individual structure. The systems were furthermore shown to catalyze and re‐equilibrate their own formation through a previously unknown thiourea‐catalyzed transimination process.
Drug Delivery Nanocarriers from a Fully Degradable PEG‐Conjugated Polyester with a Reduction‐Responsive Backbone
Authors: Yameen Basit , Vilos Cristian , Choi Won Il , Whyte Andrew , Huang Jining , Pollit Lori , Farokhzad Omid C. 
Published: July 2015

AbstractThe remarkably high intracellular concentration of reducing agents is an excellent endogenous stimulus for designing nanocarriers programmed for intracellular delivery of therapeutic agents. However, despite their excellent biodegradability profiles, aliphatic polyesters that are fully degradable in response to the intracellular reducing environment are rare. Herein, a reduction‐responsive drug delivery nanocarrier derived from a linear polyester bearing disulfide bonds is reported. The reduction‐responsive polyester is synthesized via a convenient polycondensation process. After conjugation of terminal carboxylic acid groups of polyester to polyethylene glycol (PEG), the resulting polymer self‐assembles into nanoparticles that are capable of encapsulating dye and anticancer drug molecules. The reduction‐responsive nanoparticles display a fast payload release rate in response to the intracellular reducing environment, which translates into superior anticancer activity towards PC‐3 cells.
Total Synthesis of cis‐Clavicipitic Acid from Asparagine via Ir‐Catalyzed CH bond Activation as a Key Step
Authors: Tahara Yu‐ki , Ito Mamoru , Kanyiva Kyalo Stephen , Shibata Takanori 
Published: July 2015

Abstract4‐Substituted tryptophan derivatives and the total synthesis of cis‐clavicipitic acid were achieved in reactions in which Ir‐catalyzed CH bond activation was a key step. The starting material for these reactions is asparagine, which is a cheap natural amino acid. The reductive amination step from the 4‐substituted tryptophan derivative gave cis‐clavicipitic acid with perfect diastereoselectivity.
A Versatile Approach to CF3‐Containing 2‐Pyrrolidones by Tandem Michael Addition–Cyclization: Exemplification in the Synthesis of Amidine Class BACE1 Inhibitors
Authors: Mateu Natalia , Ciordia Myriam , Delgado Oscar , Sánchez‐Roselló María , Trabanco Andrés A. , Van Gool Michiel , Tresadern Gary , Pérez‐Benito Laura , Fustero Santos 
Published: July 2015

AbstractThe groups of Santos Fustero at the University of Valencia (Spain) and Oscar Delgado at Janssen Research and Development (Spain) have been invited for the front cover of this issue. The image depicts the docking of one of the β‐secretase 1 (BACE1) inhibitors encapsulated in a sketch of the human brain. Read the full text of the article at 10.1002/chem.201501662.
Effects of melatonin on physical fatigue and other symptoms in patients with advanced cancer receiving palliative care: A double‐blind placebo‐controlled crossover trial
Authors: Lund Rasmussen Charlotte , Klee Olsen Marc , Thit Johnsen Anna , Aagaard Petersen Morten , Lindholm Helena , Andersen Line , Villadsen Birgit , Groenvold Mogens , Pedersen Lise 
Published: July 2015

BACKGROUNDPatients with advanced cancer often experience fatigue and other symptoms that negatively impact their quality of life. The current trial investigated the effect of melatonin on fatigue and other symptoms in patients with advanced cancer.METHODSPatients who were aged ≥18 years, had a histologically confirmed stage IV cancer (TNM Classification), and who reported feeling significantly tired were recruited from the palliative care unit at the study institution. The study was a double‐blind, randomized, placebo‐controlled crossover trial. Patients received 1 week of melatonin at a dose of 20 mg or a placebo orally each night, before crossing over and receiving the opposite treatment for 1 week. Between the 2 periods, a washout period of 2 days was implemented. Outcomes were measured using the Multidimensional Fatigue Inventory (MFI‐20) and The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire. Physical fatigue from the MFI‐20 was the primary outcome. The primary analysis was a complete complier analysis (ie, it included only those patients who had consumed at least 5 capsules per week and who had answered the MFI‐20 on days 1, 7, 10, and 17). Sensitivity analysis using multiple imputations including all randomized patients and all patients completing the intervention were conducted.RESULTSA total of 72 patients were randomized. Fifty patients completed the intervention and 44 patients were complete compliers. No significant differences between the placebo and melatonin periods were found for physical fatigue, secondary outcomes, or explorative outcomes.CONCLUSIONSIn the current study, oral melatonin at a dose of 20 mg was not found to improve fatigue or other symptoms in patients with advanced cancer. Cancer 2015;121:3727–3736. © 2015 American Cancer Society.
Switch from distress to well‐being by strong emotions: Speculations on three clinical vignettes
Authors: Calanchini Carlo 
Published: July 2015

ABSTRACTStarting from three clinical vignettes representing two mental disorders and different approaches to their treatment, we ask whether and how an unexpected event occurring at a particular time in a person's life could provoke such strong emotions as to determine a sudden transition from a state of severe distress to one of well‐being.In this transition, we postulate that a major role is played by biological tendencies and brain plasticity under the influence of psychotherapy and positive emotions, emotions—especially trust, the sense of being cared for, and falling in love—that are awakened by openness to novelty and to the Other. Neurobiologically, a sudden improvement could be ascribed to an oxytocinergic action that, combined with dopaminergic circuits, can restore a state of well‐being, safe attachment, and gratification. J. Comp. Neurol. 524:1687–1694, 2016. © 2015 Wiley Periodicals, Inc.
FACE‐IT: A science gateway for food security research
Authors: Montella Raffaele , Kelly David , Xiong Wei , Brizius Alison , Elliott Joshua , Madduri Ravi , Maheshwari Ketan , Porter Cheryl , Vilter Peter , Wilde Michael , Zhang Meng , Foster Ian 
Published: July 2015

SummaryProgress in sustainability science is hindered by challenges in creating and managing complex data acquisition, processing, simulation, post‐processing, and intercomparison pipelines. To address these challenges, we developed the Framework to Advance Climate, Economic, and Impact Investigations with Information Technology (FACE‐IT) for crop and climate impact assessments. This integrated data processing and simulation framework enables data ingest from geospatial archives; data regridding, aggregation, and other processing prior to simulation; large‐scale climate impact simulations with agricultural and other models, leveraging high‐performance and cloud computing; and post‐processing to produce aggregated yields and ensemble variables needed for statistics, for model intercomparison, and to connect biophysical models to global and regional economic models. FACE‐IT leverages the capabilities of the Globus Galaxies platform to enable the capture of workflows and outputs in well‐defined, reusable, and comparable forms. We describe FACE‐IT and applications within the Agricultural Model Intercomparison and Improvement Project and the Center for Robust Decision‐making on Climate and Energy Policy. Copyright © 2015 John Wiley & Sons, Ltd.
Insight into the Binding Mode of Agonists of the Nicotinic Acetylcholine Receptor from Calculated Electron Densities
Authors: Beck Michael E. , Gutbrod Oliver , Matthiesen Svend 
Published: July 2015

AbstractInsect nicotinic acetylcholine receptors (nAChRs) are among the most prominent and most economically important insecticide targets. Thus, an understanding of the modes of binding of respective agonists is important for the design of specific compounds with favorable vertebrate profiles. In the case ofnAChRs, the lack of available high‐resolution X‐ray structures leaves theoretical considerations as the only viable option. Starting from classical homology and docking approaches, binding mode hypotheses are created for five agonists of thenAChR, covering insecticides in the main group 4 of the Insecticide Resistance Action Committee (IRAC) mode of action (MoA) classification, namely, neonicotinoids, nicotine, sulfoxaflor, and butenolides. To better understand these binding modes, the topologies of calculated electron densities of small‐model systems are analyzed in the framework of the quantum theory of atoms in molecules. The theoretically obtained modes of binding are very much in line with the biology‐driven IRAC MoA classification of the investigated ligands.
Real‐Time Band‐Selective Homonuclear Proton Decoupling for Improving Sensitivity and Resolution in Phase‐Sensitive J‐Resolved Spectroscopy
Authors: Verma Ajay , Baishya Bikash 
Published: July 2015

AbstractReal‐time band‐selective homonuclear 1H decoupling during data acquisition of z‐filtered J‐resolved spectroscopy produces 1H‐decoupled 1H NMR spectra and leads to sensitivity enhancement and improved resolution, and thus aids the measurement of J couplings and residual dipolar couplings in crowded regions of 1H NMR spectrum. High quality spectra from peptides, organic molecules, and also from enantiomers dissolved in weakly aligned chiral media are reported.
Vibrational Dephasing in Ionic Liquids as a Signature of Hydrogen Bonding
Authors: Chatzipapadopoulos Susana , Zentel Tobias , Ludwig Ralf , Lütgens Matthias , Lochbrunner Stefan , Kühn Oliver 
Published: July 2015

AbstractUnderstanding both structure and dynamics is crucial for producing tailor‐made ionic liquids (ILs). We studied the vibrational and structural dynamics of medium versus weakly hydrogen‐bonded CH groups of the imidazolium ring in ILs of the type [1‐alkyl‐3‐methylimidazolium][bis(trifluoromethanesulfonyl)imide] ([Cnmim][NTf2]), with n=1, 2, and 8, by time‐resolved coherent anti‐Stokes Raman scattering (CARS) and quantum‐classical hybrid (QCH) simulations. From the time series of the CARS spectra, dephasing times were extracted by modeling the full nonlinear response. From the QCH calculations, pure dephasing times were obtained by analyzing the distribution of transition frequencies. Experiments and calculations reveal larger dephasing rates for the vibrational stretching modes of C(2)H compared with the more weakly hydrogen‐bonded C(4,5)H. This finding can be understood in terms of different H‐bonding motifs and the fast interconversion between them. Differences in population relaxation rates are attributed to Fermi resonance interactions.