bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Segregated Lamello‐Columnar Mesophase Organizations and Fast Charge Carrier Mobility in New Discotic Donor–Acceptor Triads
Authors: Zhao Ke‐Qing , An Ling‐Ling , Zhang Xiao‐Bo , Yu Wen‐Hao , Hu Ping , Wang Bi‐Qin , Xu Jing , Zeng Qing‐Dao , Monobe Hirosato , Shimizu Yo , Heinrich Benoît , Donnio Bertrand 
Published: June 2015

AbstractFour new donor–acceptor triads (D–A–D) based on discotic and arylene mesogens have been synthesized by using Sonogashira coupling and cyclization reactions. This family of triads consists of two side‐on pending triphenylene mesogens, acting as the electron‐donating groups (D), laterally connected through short lipophilic spacers to a central perylenediimide (PI), benzo[ghi]perylenediimide (BI), or coronenediimide (CI) molecular unit, respectively, playing the role of the electron acceptor (A). All D–A–D triads self‐organize to form a lamello‐columnar oblique mesophase, with a highly segregated donor–acceptor (D–A) heterojunction organization, consequent to efficient molecular self‐sorting. The structure consists in the regular alternation of two disrupted rows of triphenylene columns and a continuous row of diimine species. High‐resolution STM images demonstrate that PI‐TP2 forms stable 2D self‐assembly nanostructures with some various degrees of regularity, whereas the other triads do not self‐organize into ordered architectures. The electron‐transport mobility of CI‐TP2, measured by time‐of‐flight at 200 °C in the mesophase, is one order of magnitude higher than the hole mobility. By means of this specific molecular designing idea, we realized and demonstrated for the first time the so‐called p–n heterojunction at the molecular level in which the electron‐rich triphenylene columns act as the hole transient pathways, and the coronenediimide stacks form the electron‐transport channels.
A Nitro‐Functionalized Metal–Organic Framework as a Reaction‐Based Fluorescence Turn‐On Probe for Rapid and Selective H2S Detection
Authors: Nagarkar Sanjog S. , Desai Aamod V. , Ghosh Sujit K. 
Published: June 2015

AbstractThe toxic gas H2S has recently emerged as one of the important signaling molecules in biological systems. Thus understanding the production, distribution, and mode of action of H2S in biological system is important, but the fleeting and reactive nature of H2S makes it a daunting task. Herein we report a biocompatible, nitro‐functionalized metal–organic framework as reaction‐based fluorescence turn‐on probe for fast and selective H2S detection. The selective turn‐on performance of MOF remains unaffected even in presence of competing biomolecules.
Visible‐Light‐Driven Intermolecular [2+2] Cycloadditions between Coumarin‐3‐Carboxylates and Acrylamide Analogs
Authors: Liu Qiang , Zhu Fu‐Ping , Jin Xiao‐Ling , Wang Xiao‐Ju , Chen Han , Wu Li‐Zhu 
Published: June 2015

AbstractThis paper reports a room temperature visible‐light‐driven protocol for the intermolecular [2+2] cycloadditions between coumarin‐3‐carboxylates and acrylamides analogs by an energy‐transfer process. Using an iridium complex FIrPic as a photosensitizer and a 3 W blue LED as a light source, an array of cyclobutabenzocypyranones were prepared in moderate to excellent yields.
Fluorescent Pyrene‐Based Bis‐azole Compounds: Synthesis and Photophysical Analysis
Authors: Ibáñez Susana , Guerrero Antonio , Poyatos Macarena , Peris Eduardo 
Published: June 2015

AbstractA rational synthetic procedure for the preparation of a series of pyrene‐based neutral and dicationic bis‐azole compounds is reported. The method allows the tailored design of pyrene‐based azoles with different substituents at the nitrogen atoms of the heterocycles, for which the relative conformation of the resulting bis‐azoles can be easily controlled. The bis‐azoliums were used for the preparation of the related diplatinum complexes by reaction with [{Pt(ppy)(μ‐Cl)2}2] (ppy=2‐phenylpyridinate). The X‐ray molecular structure of one of the resulting compounds, a diplatinum(II) bis(N‐heterocyclic carbene) complex, is described. Studies on the photophysical properties of all new species are described. The emission of the bis‐azole‐based compounds seems to be independent of their substitution patterns, which basically indicates that physical properties such as solubility, melting point, and viscosity can be fine‐tuned while maintaining the luminescence properties. Finally, the energies associated with the HOMO and LUMO levels suggest that this family provides versatility to match the energy levels of a wide range of host materials, which is important for the preparation of organic light‐emitting devices.
Silver‐Catalyzed Coupling of Two CH Groups and One‐Pot Synthesis of Tetrasubstituted Furans, Thiophenes, and Pyrroles
Authors: Mao Shuai , Zhu Xue‐Qing , Gao Ya‐Ru , Guo Dong‐Dong , Wang Yong‐Qiang 
Published: June 2015

AbstractSilver‐catalyzed coupling of two CH groups to form 1,4‐diketones have been developed for the first time. The resultant ketones then undergo cyclization to synthesize tetrasubstituted furans, thiophenes, and pyrroles from benzyl ketone derivatives in a one‐pot reaction process. This highly‐efficient synthetic method, which utilizes air as the terminal oxidant and readily accessible starting materials, displays a wide substrate scope and broad functional‐group tolerance.
Highly Chemoselective Catalytic Coupling of Substituted Oxetanes and Carbon Dioxide
Authors: Rintjema Jeroen , Guo Wusheng , Martin Eddy , Escudero‐Adán Eduardo C. , Kleij Arjan W. 
Published: June 2015

AbstractThe chemoselective coupling of oxetanes and carbon dioxide to afford functional, heterocyclic organic compounds known as six‐membered cyclic carbonates remains a challenging topic. Here, an effective method for their synthesis relying on the use of Al catalysis is described. The catalytic reactions can be carried out with excellent selectivity for the cyclic carbonate product tolerating various (functional) groups present in the 2‐ and 3‐position(s) of the oxetane ring. The presented methodology is the first general approach towards the formation of six‐membered cyclic carbonates (6MCCs) through oxetane/CO2 coupling chemistry. Apart from a series of substituted six‐membered cyclic carbonates, also the unprecedented room‐temperature coupling of oxetanes and CO2 is disclosed giving, depending on the structural features of the substrate, a variety of five‐ and six‐membered heterocyclic products. A mechanistic rationale is presented for their formation and support for the intermediary presence of a carbonic acid derivative is given. The presented functional carbonates may hold great promise as building blocks in organic synthesis and the development of new, biodegradable polymers.
Synergistic Stereocontrol in the Enantioselective Ruthenium‐Catalyzed Sulfoxidation of Spirodithiolane‐Indolones
Authors: Zhong Fangrui , Pöthig Alexander , Bach Thorsten 
Published: June 2015

AbstractA chiral ruthenium catalyst was developed for the enantioselective sulfoxidation of the title compounds. The catalyst combines two elements of chirality, a chiral pybox ligand and a chiral bicylic lactam unit, to which the ligand is attached. The latter unit was shown to improve significantly the performance of the catalyst by exposing one of the two enantiotopic sulfur atoms to the active site via hydrogen‐bond mediated coordination. Ten differently substituted substrates were converted into the respective sulfoxides in yields of 52–71 % and with ≥90 % ee.
Dipeptide‐Derived Multifunctional Quaternary Phosphonium Salt Catalyzed Asymmetric Cyclizations via a Tandem Michael Addition/SN2 Sequence
Authors: Cao Dongdong , Zhang Jiaxing , Wang Hongyu , Zhao Gang 
Published: June 2015

AbstractA novel family of dipeptide‐based multifunctional quaternary phosphonium salts has been developed as chiral phase‐transfer catalysts, which feature ready accessibility and structure modularity, allowing easy fine‐tunings of activity. They demonstrated high efficiency in catalyzing the tandem asymmetric Michael addition/intramolecular SN2 reaction between 6 or 7‐substituted conjugate enones and malonates, providing synthetically important five or six‐membered carbocycles and heterocycles in good yields and with good to excellent enantioselectivities.
Metal–Organic Frameworks (MOFs) as Multivalent Materials: Size Control and Surface Functionalization by Monovalent Capping Ligands
Authors: Rijnaarts Timon , Mejia‐Ariza Raquel , Egberink Richard J. M. , van Roosmalen Wies , Huskens Jurriaan 
Published: June 2015

AbstractControl over particle size and composition are pivotal to tune the properties of metal organic frameworks (MOFs), for example, for biomedical applications. Particle‐size control and functionalization of MIL‐88A were achieved by using stoichiometric replacement of a small fraction of the divalent fumarate by monovalent capping ligands. A fluorine‐capping ligand was used to quantify the surface coverage of capping ligand at the surface of MIL‐88A. Size control at the nanoscale was achieved by using a monovalent carboxylic acid‐functionalized poly(ethylene glycol) (PEG‐COOH) ligand at different concentrations. Finally, a biotin–carboxylic acid capping ligand was used to functionalize MIL‐88A to bind fluorescently labeled streptavidin as an example towards bioapplications.
Recent Advances in Stereoselective Drug Targeting
Authors: Zask Arie , Ellestad George A. 
Published: June 2015

AbstractReviewed here are some recent examples of medically important protein targets for which stereoselective drugs have been identified. These include heat shock protein 90 (Hsp90) inhibitors as anticancer agents; transient receptor potential vanilloid type 1 antagonists as new analgesics; stereospecific inhibition of human mutT homolog MTH1 for cancer treatment; the stereoselective binding of R‐ and S‐propranolol by the α1–acid glycoprotein transporter; metallohelical complexes that are nonpeptide α‐helical mimetics that enantioselectively target Aβ amyloid for the treatment of Alzheimer's disease; metallohelical assemblies with promising antimicrobial activity that enantioselectively target DNA of resistant bacteria; nonpeptide α‐helical metallohelices that target the DNA of cisplatin‐resistant cancer cells; diastereomeric selectivity of phenanthriplatin‐guanine adducts; and phenazine biosynthetic enzyme active sites that can host both enantiomers of a racemic ligand simultaneously. Chirality 27:589–597, 2015. © 2015 Wiley Periodicals, Inc.
Glycosaminoglycan and DNA Binding Induced Intra‐ and Intermolecular Exciton Coupling of the bis‐4‐Aminoquinoline Surfen
Authors: Zsila Ferenc 
Published: June 2015

AbstractDespite the diverse biological activities of the glycosaminoglycan (GAG) antagonist surfen, the molecular details of its interaction with biomacromolecules remain poorly understood. Therefore, heparin and DNA binding properties of surfen were studied by circular dichroism (CD) and UV absorption spectroscopy methods. High‐affinity (Ka ~ 107 M‐1) association of surfen to the chiral heparin chain gives rise to a characteristic biphasic CD pattern due to the conformational twist of the aminoquinoline moieties around the central urea bridge. At higher drug loading, intermolecular stacking of surfen molecules alters the induced CD profile and also provokes strong UV hypochromism. In contrast to the right‐handed heparin template, binding of surfen to the left‐helicity chondroitin sulfate chains produces inverted CD pattern. Large UV hypochromism as well as polyphasic induced ellipticity bands indicate that surfen intercalates between the base pairs of calf‐thymus DNA. Extensive CD spectroscopic changes observed at higher drug binding ratios refer to cooperative binding interactions between the intercalated drug molecules. The inherent conformational flexibility of surfen demonstrated here for the first time is important in its binding to distinct macromolecular targets and should be considered for rational drug design of novel GAG antagonists. Chirality 27:605–612, 2015. © 2015 Wiley Periodicals, Inc.
Sorting Semiconducting Single‐Walled Carbon Nanotubes by Water‐Soluble Polyfluorene Assisted Electrophoresis and Its Application in Field‐effect Transistors
Authors: Zhu Haoyun , Wang Weizhi 
Published: June 2015

AbstractWe report a considerably promising method based on agarose gel electrophoresis (AGE) to separate single‐walled carbon nanotubes by adding a water‐soluble polyfluorene (w‐PFO) as surfactant into the agarose gel. In this effective method, the AGE/w‐PFO gel network will trap more semiconducting single‐walled carbon nanotubes (SWNTs) with the assistance of w‐PFO, for the strong interaction between w‐PFO and semiconducting species. The optical absorbance, photoluminescence emission and resonant Raman scattering characterization were used to verify the separation effect. The purity of separated semiconducting species is as high as (98±1)%. The demonstrated field effect transistors give the on/off ratio and mobility about 27000 and 10.2 cm2·V−1·s−1, respectively.
A more accurate tuning‐matching technique for NMR probes using wobulation and variable phase shifter
Authors: Ferrand Guillaume , Luong Michel , Huber Gaspard , Desvaux Hervé 
Published: June 2015

ABSTRACTFor optimizing sensitivity and RF excitation, high resolution NMR probes have to be tuned at the Larmor frequency and matched to 50 Ω‐transmission lines to which they are connected. For achieving this setting, one usually resorts to the wobulation function which consists in sweeping the frequency of the power source while monitoring and minimizing the reflected power taken from a directional coupler through adjusting the tuning and matching capacitors. However, the presence of a transmission‐reception switch between the directional coupler and the probe leads to the appearance of extra loss and reactance, and affects the determined values of the previous mentioned capacitors. Even if this situation is usually satisfactory, the true tuning‐matching condition is required for optimal NMR sensitivity and for reliable spectra analyses when nonlinear effects are present (radiation damping, spin‐noise experiments, etc.). To circumvent the need of network analyzer directly attached to the probe for finding this optimal tuning‐matching condition, in the current work, we report a procedure which combines wobulation and choice of a transmission‐line phase shift obtained by a variable phase shifter inserted between the probe and the switch. The technique was successfully validated with help of a network analyzer. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 45B: 59–68, 2015
Ultra‐small Palladium Nanoparticle Decorated Carbon Nanotubes: Conductivity and Reactivity
Authors: Li Xiuting , Batchelor‐McAuley Christopher , Tschulik Kristina , Shao Lidong , Compton Richard G. 
Published: June 2015

AbstractCarbon nanotubes decorated with ultra‐small metal nanoparticles are of great value in catalysis. We report that individual multiwalled carbon nanotubes decorated with ultra‐small palladium nanoparticles can be detected by using the nano‐impacts method. The high conductivity and reactivity of each decorated carbon nanotube is directly evidenced; this is achieved through studying the proton‐reduction reaction for the underpotential deposition of hydrogen onto the nanoparticles decorated on the carbon nanotube walls. The reductive spikes from current amplification are analyzed to estimate the approximate length of the decorated carbon nanotubes, revealing that the decorated carbon nanotubes are electroactive along its entire length of several micrometers.
A new parallel ZVS converter with less power switches and low current stress components
Authors: Lin Bor‐Ren , Chu Chung‐Wei 
Published: June 2015

SummaryA new direct current (DC)/DC converter with parallel circuits is presented for medium voltage and power applications. There are five pulse‐width modulation circuits in the proposed converter to reduce current stress at low voltage side for high output current applications. These five circuits share the same power switches in order to reduce switch counts. To reduce the converter size, conduction loss, and voltage stress of power semiconductors, the series connections of power metal‐oxide‐semiconductor field‐effect transistor (MOSFET) with high switching frequency instead of insulated gate bipolar transistor (IGBT) with low switching frequency are adopted. Thus, the voltage stress of MOSFETs is clamped at half of input voltage. The switched capacitor circuit is adopted to balance input split capacitor voltages. Asymmetric pulse‐width modulation scheme is adopted to generate the necessary switching signals of MOSFETs and regulate output voltage. Based on the resonant behavior at the transition interval of power switches, all MOSFETs are turned on under zero voltage switching from 50% load to 100% load. The circuit configuration, operation principle, converter performance, and design example are discussed in detail. Finally, experimental verifications with a 1.92 kW prototype are provided to verify the performance of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd.
Detectability of landscape effects on recolonization increases with regional population density
Authors: Liman Anna‐Sara , Dalin Peter , Björkman Christer 
Published: June 2015

AbstractVariation in population size over time can influence our ability to identify landscape‐moderated differences in community assembly. To date, however, most studies at the landscape scale only cover snapshots in time, thereby overlooking the temporal dynamics of populations and communities. In this paper, we present data that illustrate how temporal variation in population density at a regional scale can influence landscape‐moderated variation in recolonization and population buildup in disturbed habitat patches. Four common insect species, two omnivores and two herbivores, were monitored over 8 years in 10 willow short‐rotation coppice bio‐energy stands with a four‐year disturbance regime (coppice cycle). The population densities in these regularly disturbed stands were compared to densities in 17 undisturbed natural Salix cinerea (grey willow) stands in the same region. A time series approach was used, utilizing the natural variation between years to statistically model recolonization as a function of landscape composition under two different levels of regional density. Landscape composition, i.e. relative amount of forest vs. open agricultural habitats, largely determined the density of re‐colonizing populations following willow coppicing in three of the four species. However, the impact of landscape composition was not detectable in years with low regional density. Our results illustrate that landscape‐moderated recolonization can change over time and that considering the temporal dynamics of populations may be crucial when designing and evaluating studies at landscape level.
Reconciling actual and perceived rates of predation by domestic cats
Authors: McDonald Jennifer L. , Maclean Mairead , Evans Matthew R. , Hodgson Dave J. 
Published: June 2015

AbstractThe predation of wildlife by domestic cats (Felis catus) is a complex problem: Cats are popular companion animals in modern society but are also acknowledged predators of birds, herpetofauna, invertebrates, and small mammals. A comprehensive understanding of this conservation issue demands an understanding of both the ecological consequence of owning a domestic cat and the attitudes of cat owners. Here, we determine whether cat owners are aware of the predatory behavior of their cats, using data collected from 86 cats in two UK villages. We examine whether the amount of prey their cat returns influences the attitudes of 45 cat owners toward the broader issue of domestic cat predation. We also contribute to the wider understanding of physiological, spatial, and behavioral drivers of prey returns among cats. We find an association between actual prey returns and owner predictions at the coarse scale of predatory/nonpredatory behavior, but no correlation between the observed and predicted prey‐return rates among predatory cats. Cat owners generally disagreed with the statement that cats are harmful to wildlife, and disfavored all mitigation options apart from neutering. These attitudes were uncorrelated with the predatory behavior of their cats. Cat owners failed to perceive the magnitude of their cats' impacts on wildlife and were not influenced by ecological information. Management options for the mitigation of cat predation appear unlikely to work if they focus on “predation awareness” campaigns or restrictions of cat freedom.
Ruthenium Carboxylate Complexes as Efficient Catalysts for the Addition of Carboxylic Acids to Propargylic Alcohols
Authors: Jeschke Janine , Gäbler Christian , Korb Marcus , Rüffer Tobias , Lang Heinrich 
Published: June 2015

AbstractInvited for the cover of this issue is the group of Heinrich Lang at the Technische Universität Chemnitz, Germany. The cover image shows the atom‐economical and highly selective addition of carboxylic acids to propargylic alcohols to give β‐oxopropyl esters. This conversion is catalyzed by ruthenium complexes, represented by the skater in our picture.
A Theoretical Probe of Mechanistic Trichotomy in RhIII‐Catalyzed Annulation with Alkyne MIDA Boronates: Roles of Salt, Solvent, and Coupling Partner
Authors: Zhao Liu , Fang De‐Cai 
Published: June 2015

AbstractA theoretical study of the role of added salts, solvent effects, and substrate scope for the RhIII‐catalyzed C–H activation and annulation of N‐(pivaloyloxy)benzamide and alkyne MIDA boronates has been performed by means of DFT calculations. Computationally, the high reactivity of terminal alkynyl MIDA boronates originates from the electronic stability of the sp3‐hybridized boronate. The critical role of Cu(OAc)2 as additive is such that it can be viewed as an intermediate catalyst, assisting the removal of the directing group and facilitating the conversion of RhI into RhIII in the intramolecular oxidative addition process. In contrast, AgOAc seems to have an opposite effect because it increases the activation free‐energy barrier for the migratory insertion step, retarding the chemical transformation and reducing the product yield. Solvent selectivity, regioselectivity and substituent effects have also been investigated.
Biosorption of cadmium metal ions on raw and chemically modified walnut shells
Authors: Gondhalekar Sachin C. , Shukla Sanjeev R. 
Published: June 2015

The abundantly available agricultural waste product walnut shells were treated with alkali for enhancement in adsorptive capacity for Cd(II) ions. The raw walnut shells (RWS) and alkali treated walnut shells (AWS) were characterized for functional groups and morphological changes using FTIR and SEM analysis. The adsorption increased drastically between pH 2 and 6. The Langmuir isotherm model provided a better fit with the experimental data than Freundlich by giving high correlation coefficients. The biosorption capacity of RWS and AWS for Cd(II) ions was found to be 4.20 and 14.29 mg g−1, respectively. Dubinin–Radushkevich (D‐R) isotherm model was used to find out the mean adsorption energy. The adsorption followed pseudo‐second order kinetics, suggesting monolayer coverage and a chemisorption process. The thermodynamic parameters including change in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were derived. Negative value of ΔG confirmed spontaneity of biosorption. Desorption efficiency showed no significant decrease till third cycle. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1613–1619, 2015