bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Easy One‐Pot Synthesis of Diverse 2,5‐Di(2‐pyridyl)pyrroles: A Versatile Entry Point to Metal Complexes of Functionalised, Meridial and Tridentate 2,5‐Di(2‐pyridyl)pyrrolato Ligands
Authors: McSkimming Alex , Diachenko Vera , London Rachel , Olrich Kiara , Onie C. Jessica , Bhadbhade Mohan M. , Bucknall Martin P. , Read Roger W. , Colbran Stephen B. 
Published: July 2014

AbstractA wide variety of 2,5‐di(2‐pyridyl)pyrroles (dppHs) substituted at the C3 and C4 positions of the pyrrole core were obtained by direct condensation of a 2‐pyridylcarboxaldehyde (2 equiv), an α‐methylene ketone with at least one electron‐withdrawing substituent and ammonium acetate. A novel 2,5‐di(1,10‐phenanthrolin‐2‐yl)pyrrole was also characterised. The dppHs provide a direct, quick entry to dipyridylpyrrolato (dpp−)–metal complexes. The meridial tridentate dpp− ligand is a useful anionic analogue of the terpyridyl ligand. The first (dpp)Ru complexes are described; the 3,4‐substitution of the central pyrrole significantly perturbs the potentials of the redox processes of these complexes. A [(dpp)Ru(bpy)(MeCN)]+ (bpy=2,2′‐bipyridine) complex is an electrocatalyst for the reductive disproportionation of carbon dioxide to carbon monoxide and the carbonate ion.
Metal‐Substituted Zeolitic Imidazolate Framework ZIF‐108: Gas‐Sorption and Membrane‐Separation Properties
Authors: Ban Yujie , Li Yanshuo , Peng Yuan , Jin Hua , Jiao Wenmei , Liu Xinlei , Yang Weishen 
Published: July 2014

AbstractA series of dual‐metal zeolitic imidazolate framework (ZIF) crystals with SOD and RHO topologies was synthesised by metal substitution from ZIF‐108 (Zn(2‐nitroimidazolate)2, SOD topology) as the parent material. This was based on the concept that metal substitution of ZIF‐108 requires a much lower activation energy than homogenous nucleation owing to the metastability of ZIF‐108. In‐depth investigations of the formation processes of the daughter ZIFs indicated that the transformation of ZIF‐108 is a dissolution/heterogeneous nucleation process. Typical isostructural Co2+ substitution mainly occurs at the outer surface of ZIF‐108 and results in a core–shell structure. On the contrary, the Cu2+‐substituted ZIF has a RHO topology with a homogeneous distribution of Cu2+ ions in the structure. Substitution with Ni2+ resulted in a remarkable enhancement in adsorption selectivity toward CO2 over N2 by a factor of up to 227. With Co2+‐substituted nanoparticles as inorganic filler, a mixed matrix membrane based on polysulfone displayed greatly improved performance in the separation of H2/CH4, CO2/N2 and CO2/CH4.
Combining Topological and Steric Constraints for the Preparation of Heteroleptic Copper(I) Complexes
Authors: Mohankumar Meera , Monti Filippo , Holler Michel , Niess Frédéric , Delavaux‐Nicot Béatrice , Armaroli Nicola , Sauvage Jean‐Pierre , Nierengarten Jean‐François 
Published: July 2014

AbstractHeteroleptic copper(I) complexes have been prepared from a macrocyclic ligand incorporating a 2,9‐diphenyl‐1,10‐phenanthroline subunit (M30) and two bis‐phosphines, namely bis[(2‐diphenylphosphino)phenyl] ether (POP) and 1,3‐bis(diphenylphosphino)propane (dppp). In both cases, the diphenylphosphino moieties of the PP ligand are too bulky to pass through the 30‐membered ring of M30 during the coordination process, hence the formation of C2v‐symmetrical pseudo‐rotaxanes is prevented. When POP is used, X‐ray crystal structure analysis shows the formation of a highly distorted [Cu(M30)(POP)]+ complex in which the POP ligand is only partially threaded through the M30 unit. This compound is poorly stable as the CuI cation is not in a favorable coordination environment due to steric constraints. By contrast, in the case of dppp, the bis‐phosphine ligand undergoes both steric and topological constraints and adopts a nonchelating coordination mode to generate [Cu2(M30)2(μ‐dppp)](BF4)2. This compound exhibits metal‐to‐ligand charge transfer (MLCT) emission characterized by a very large Stokes’ shift (≈200 nm) that is not attributed to a dramatic structural distortion between the ground and the emitting states but to very weak MLCT absorption transitions at longer wavelengths. Accordingly, [Cu2(M30)2(μ‐dppp)](BF4)2 shows unusually high luminescence quantum yields for CuI complexes, both in solution and in the solid state (0.5 and 7 %, respectively).
Diastereo‐ and Enantioselective Construction of a Bispirooxindole Scaffold Containing a Tetrahydro‐β‐carboline Moiety through an Organocatalytic Asymmetric Cascade Reaction
Authors: Dai Wei , Lu Han , Li Xin , Shi Feng , Tu Shu‐Jiang 
Published: July 2014

AbstractThe first catalytic asymmetric construction of a new class of bispirooxindole scaffold‐containing tetrahydro‐β‐carboline moiety has been established through chiral phosphoric acid‐catalyzed three‐component cascade Michael/Pictet–Spengler reactions of isatin‐derived 3‐indolylmethanols, isatins, and amino‐ester, which afforded structurally complex and diverse bispirooxindoles with one quaternary and one tetrasubstituted stereogenic centers in excellent stereoselectivities (all >95:5 diastereomeric ratio (d.r.), up to 98:2 enantiomeric ratio (e.r.)). This intriguing class of chiral bispirooxindoles integrated the two important structures of tetrahydro‐β‐carboline and bispirooxindole, both of them possessing significant bioactivities. This approach also combined the merits of asymmetric organocatalysis and multicomponent tandem reaction, which provided a unique strategy for the preparation of structurally rigid bispiro‐architectures with concomitant creation of multiple quaternary stereogenic centers.
Design of Stereoelectronically Promoted Super Lewis Acids and Unprecedented Chemistry of Their Complexes
Authors: Foroutan‐Nejad Cina , Vicha Jan , Marek Radek 
Published: July 2014

AbstractA new family of stereoelectronically promoted aluminum and scandium super Lewis acids is introduced on the basis of state‐of‐the‐art computations. Structures of these molecules are designed to minimize resonance electron donation to central metal atoms in the Lewis acids. Acidity of these species is evaluated on the basis of their fluoride‐ion affinities relative to the antimony pentafluoride reference system. It is demonstrated that introduced changes in the stereochemistry of the designed ligands increase acidity considerably relative to Al and Sc complexes with analogous monodentate ligands. The high stability of fluoride complexes of these species makes them ideal candidates to be used as weakly coordinating anions in combination with highly reactive cations instead of conventional Lewis acid–fluoride complexes. Further, the interaction of all designed molecules with methane is investigated. All studied acids form stable pentavalent‐carbon complexes with methane. In addition, interactions of the strongest acid of this family with very weak bases, namely, H2, N2, carbon oxides, and noble gases were investigated; it is demonstrated that this compound can form considerably stable complexes with the aforementioned molecules. To the best of our knowledge, carbonyl and nitrogen complexes of this species are the first hypothetical four‐coordinated carbonyl and nitrogen complexes of aluminum. The nature of bonding in these systems is studied in detail by various bonding analysis approaches.
Efficient Asymmetric Synthesis of 1‐Cyano‐tetrahydroisoquinolines from Lipase Dual Activity and Opposite Enantioselectivities in α‐Aminonitrile Resolution
Authors: Sakulsombat Morakot , Vongvilai Pornrapee , Ramström Olof 
Published: July 2014

AbstractDual promiscuous racemization/amidation activities of lipases leading to efficient dynamic kinetic resolution protocols of racemic α‐aminonitrile compounds are described. α‐Amidonitrile products of high enantiomeric purity could be formed in high yields. Several lipases from different sources were shown to exhibit the dual catalytic activities, where opposite enantioselectivities could be recorded for certain substrates.
Amino‐Functionalized Pillar[5]arene
Authors: Strutt Nathan L. , Zhang Huacheng , Schneebeli Severin T. , Stoddart J. Fraser 
Published: July 2014

AbstractThe recently introduced pillar[n]arenes have provided chemists with receptors that, when incorporated into materials, confer unique properties upon them. The symmetrical rims and cylindrical shape of pillar[5]arene begs the question—can these pillar‐like receptors be linked covalently end‐to‐end in order to create tubular structures by a growth‐from‐template approach? In our efforts to produce these one‐dimensional extended structures, we have developed a new method of functionalizing pillar[5]arene in which one of the five hydroquinone units is converted into a diaminobenzoquinone analogue. The resulting diaminopillar[5]arene derivative, which undergoes a stereochemical inversion process that is slow on the 1H NMR timescale, can be chemically modified yet further in a direction that is orthogonal to the plane of its methylene bridging carbons through the formation of oxazole heterocycles. This strategy has been employed to create rigid oligomers that resemble one‐dimensional tubular arrays. As a proof‐of‐principle, a rigid pillar[5]arene dimer has been isolated and characterized in the solution state as a 1:1 complex with an extended viologen for which it acts as a receptor.
Development of a Small Molecule Probe Capable of Discriminating Cysteine, Homocysteine, and Glutathione with Three Distinct Turn‐On Fluorescent Outputs
Authors: Wang Feiyi , Guo Zhiqian , Li Xia , Li Xiuai , Zhao Chunchang 
Published: July 2014

AbstractThe simultaneous discrimination of Cys, Hcy, and GSH by a single probe is still an unmet challenge. The design and synthesis of a small molecule probe MeO‐BODIPY‐Cl (BODIPY=boron dipyrromethene) is presented, which can allow Cys, Hcy, and GSH to be simultaneously discriminated on the basis of three distinct fluorescence turn‐on responses. The probe reacts with these thiols to form sulfenyl‐substituted BODIPY, which is followed by intramolecular displacement to yield amino‐substituted BODIPY. The kinetic rate of the intramolecular displacement reaction determines the observed different sensing behavior. Therefore, the probe responds to Cys, Hcy, and GSH with fluorescence turn‐on colors of yellow, yellow and red, and red, respectively. With this promising feature in hand, the probe was successfully used in imaging of Cys, Hcy and GSH in living cells.
Plasmonic Activation of a Fluorescent Carbazole–Oxazine Switch
Authors: Garcia‐Amorós Jaume , Swaminathan Subramani , Sortino Salvatore , Raymo Françisco M. 
Published: July 2014

AbstractThe covalent attachment of a carbazole fluorophore to an oxazine photochrome permits the reversible activation of fluorescence under optical control. Ultraviolet irradiation with a pulsed laser opens the oxazine ring to shift bathochromically the absorption of the carbazole component. Concomitant visible illumination excites selectively the carbazole fluorophore of the photochemical product to produce fluorescence. The photogenerated and fluorescent species reverts spontaneously on a submicrosecond timescale to the initial nonemissive state of the carbazole–oxazine dyad. The photochemical and photophysical properties engineered into this particular molecular switch allow the convenient monitoring of plasmonic effects on photochemical reactions with fluorescence measurements. In close proximity to silver nanoparticles, visible illumination with a continuous‐wave laser also results in fluorescence activation. The metallic nanostructures enable the two‐photon excitation of the oxazine component to induce the photochromic transformation and then facilitate the one‐photon excitation of the photochemical product to generate fluorescence. Thus, these operating principles offer the opportunity to avoid altogether the need of pulsed ultraviolet irradiation to trigger the photochromic transformation and, instead, allow fluorescence activation with a single visible source operating at low illumination power.
Vectorial Diffusion for Facile Solution‐Processed Self‐Assembly of Insoluble Semiconductors: A Case Study on Metal Phthalocyanines
Authors: Wang Chengliang , Fang Yaoguo , Wen Liaoyong , Zhou Min , Xu Yang , Zhao Huaping , De Cola Luisa , Hu Wenping , Lei Yong 
Published: July 2014

AbstractSolution processibility is one of the most intriguing properties of organic semiconductors. However, it is difficult to find a suitable solvent and solution process for most semiconductors. For example, metal phthalocyanines (MPcs) are only soluble in non‐volatile solvents, which prevent their applications from solution process. For the first time, vectorial diffusion is utilized for solution processing of MPcs. The obtained large F16CuPc and α‐phase CuPc crystals and the efficient phase separation of them suggest the vectorial diffusion process is as slow as a self‐assembly process, which is helpful to yield large crystals and purify the semiconductors. This method, which only uses common commercial solvents without any complex and expensive instruments and high‐temperature operation, provides a facile approach for purification of organic semiconductors and growth of their crystals in large quantities.
Evaluation of spectral, spectral‐element and finite‐element methods for the solution of the pellet equation
Authors: Solsvik Jannike , Jakobsen Hugo A. 
Published: July 2014

AbstractSeveral numerical methods (orthogonal collocation, Galerkin, tau, least‐squares and least‐squares with a direct minimization algorithm) are applied to solve a linear diffusion–reaction problem. The spectral, finite‐element and spectral‐element frameworks are employed to investigate the methods. Overall, the Galerkin and tau methods are considered the most universal methods.Spectral framework: With sufficient diffusion limitations, the least‐squares method suffers in general from significantly lower accuracy than the Galerkin, tau and orthogonal collocation methods. On the other hand, the least‐squares method with a direct minimization algorithm provides favourable lower system matrix condition numbers than the conventional least‐squares approach. Hence, for higher diffusion limitations, the least‐squares direct minimization formulation provides higher numerical accuracy than the conventional least‐squares method, but is still not as accurate as the Galerkin, tau and orthogonal collocation techniques. The accuracy of the least‐squares solution can compete with the other methods only in cases with low gradients in the solution.Element framework: For a highly diffusion limited problem, the element framework is considered favourable as compared to the spectral framework. On the other hand, the element approach is not as efficient as the spectral solution for small Thiele modulus solutions.
Singly Modified Amikacin and Tobramycin Derivatives Show Increased rRNA A‐Site Binding and Higher Potency against Resistant Bacteria
Authors: Fair Richard J. , McCoy Lisa S. , Hensler Mary E. , Aguilar Bernice , Nizet Victor , Tor Yitzhak 
Published: July 2014

AbstractSemisynthetic derivatives of the clinically useful aminoglycosides tobramycin and amikacin were prepared by selectively modifying their 6′′ positions with a variety of hydrogen bond donors and acceptors. Their binding to the rRNA A‐site was probed using an in vitro FRET‐based assay, and their antibacterial activities against several resistant strains (e.g., Pseudomonas aeruginosa, Klebsiella pneumonia, MRSA) were quantified by determining minimum inhibitory concentrations (MICs). The most potent derivatives were evaluated for their eukaryotic cytotoxicity. Most analogues displayed higher affinity for the bacterial A‐site than the parent compounds. Although most tobramycin analogues exhibited no improvement in antibacterial activity, several amikacin analogues showed potent and broad‐spectrum antibacterial activity against resistant bacteria. Derivatives tested for eukaryotic cytotoxicity exhibited minimal toxicity, similar to the parent compounds.
The role of SOX11 immunostaining in confirming the diagnosis of mantle cell lymphoma on fine‐needle aspiration samples
Authors: Zhang Y. Helen , Liu Joe , Dawlett Marilyn , Guo Ming , Sun Xiaoping , Gong Yun 
Published: July 2014

BACKGROUNDMantle cell lymphoma (MCL) demonstrates cytologic features that overlap with those of other types of B‐cell non‐Hodgkin lymphomas (B‐cell NHLs) containing small to medium‐sized cells. The accurate diagnosis of MCL is important because MCL has relatively more aggressive biologic behavior and thus requires specific treatment regimens. Fine‐needle aspiration (FNA) is used for diagnosing or staging lymphoma, often with the help of immunophenotyping by flow cytometry. However, the cellularity of an FNA sample may not be high enough for flow cytometry, leading to diagnostic difficulty. SOX11 immunostaining is helpful in the diagnosis of MCL in histologic sections. However, to the authors' knowledge, its diagnostic value for FNA samples has not been studied to date.METHODSImmunostains for SOX11 were performed on 69 FNA cases with final diagnoses of MCL (13 cases, including 10 classic type and 3 blastoid variant), marginal zone lymphoma (8 cases), follicular lymphoma (10 cases), small lymphocytic lymphoma (12 cases), Burkitt lymphoma (9 cases), plasma cell myeloma (7 cases), and benign lymph nodes (10 cases). Preparation types included cytospin slides (65 cases), direct smears (2 cases), and cell block sections (2 cases). The percentage of positive cells (defined as nuclear staining) and staining intensity were recorded.RESULTSAll 13 cases of MCL were positive for SOX11 staining, with 12 cases demonstrating diffuse positivity. All other types of B‐cell NHL cases, plasma cell myelomas, and benign lymph nodes were found to have negative results. Weak staining was found in 1 MCL case of blastoid variant.CONCLUSIONSSOX11 immunostaining on FNA samples is highly sensitive and specific for MCL and can be used as a reliable adjunct to confirm MCL, especially in a recurrent setting. Cancer (Cancer Cytopathol) 2014;122:892–897. © 2014 American Cancer Society.
Dynamic malicious node detection with semi‐supervised multivariate classification in cognitive wireless sensor networks
Authors: Dai Hongjun , Liu Huabo , Jia Zhiping 
Published: July 2014

SummaryUsually, wireless sensor networks are distributed massively with a number of nodes in an open large‐scale environment, and they are vulnerable to malicious attacks because the communications change dynamically and unpredictably. In this paper, we present a detection method based on multivariate classification to find out the malicious sensor nodes. It learns the features of a few type‐known node, classifies them with dynamical multivariate classification, and then establishes the sample space of all sensor nodes in the network activities to deduce the malicious nodes. The experiment results show that as long as the value of sensor node preferences and the number of active sensor nodes is stable, the false detection rate is stabilized below 0.5%. This proves that the algorithm can be used to the cognitive wireless sensor networks widely. Copyright © 2014 John Wiley & Sons, Ltd.
A game‐based incentive model for service cooperation in VANETs
Authors: Mao Yuxin , Zhu Ping , Wei Guiyi , Hassan Mohammad Mehedi , Hossain M. Anwar 
Published: July 2014

SummaryBecause of the highly dynamic topology and the unstable service status of nodes, services in vehicular ad hoc networks (VANETs) are not always reliable enough for users. Nodes in such a VANET incline to be selfish, which will even enhance this situation. In this work, we present an incentive model for VANETs to support more reliable services in network. We model the situation of service request and response in VANETs by using game theory. We consider the competitive and cooperative relationship between the nodes to formulate the game for VANETs. A contribution measurement is given in order to encourage cooperation during the game. Nodes are encouraged to provide more services to their neighbors in order to acquire more services from other nodes in our model. We also conduct a simulation for the proposed model and give detailed analysis in this work. From the results of the simulation, we argue that we could enable a VANET to support more reliable service by configuring suitable parameters for it. Copyright © 2014 John Wiley & Sons, Ltd.
A Pulse Radiolysis Study of the Dynamics of Ascorbic Acid Free Radicals within a Liposomal Environment
Authors: Kobayashi Kazuo , Seike Yumiko , Saeki Akinori , Kozawa Takahiro , Takeuchi Fusako , Tsubaki Motonari 
Published: July 2014

AbstractThe dynamics of free‐radical species in a model cellular system are examined by measuring the formation and decay of ascorbate radicals within a liposome with pulse radiolysis techniques. Upon pulse radiolysis of an N2O‐saturated aqueous solution containing ascorbate‐loaded liposome vesicles, ascorbate radicals are formed by the reaction of OH. radicals with ascorbate in unilamellar vesicles exclusively, irrespective of the presence of vesicle lipids. The radicals are found to decay rapidly compared with the decay kinetics in an aqueous solution. The distinct radical reaction kinetics in the vesicles and in bulk solution are characterized, and the kinetic data are analyzed.
High‐Yielding Synthesis of a Hetero‐Pacman Compound and the Characterization of Intermediates and Side‐Products
Authors: Schwalbe Matthias , Wrzolek Pierre , Lal Garima , Braun Beatrice 
Published: July 2014

AbstractThrough an optimized synthetic procedure, metalloligand 5, which features a hetero‐Pacman scaffold comprising a porphyrin and a terpyridine moiety, has been assembled by a double Suzuki reaction. In a subsequent step, a ruthenium‐bipyridine fragment was introduced at the terpyridine coordination site of metalloligand 5 to form complex 6, which was fully characterized and its potential application in water oxidation catalysis tested. A number of side‐products were isolated and characterized during the two‐step synthesis procedure, including a hydroxylated version of the boronic acid substituted precursor molecule derived by a base‐assisted rearrangement. The compounds described herein extend the Pacman concept to the assembly of different metal combinations with different coordination spheres and their interactions in the activation of small molecules.
Inclusion of an Iodine Molecule in a Tiara‐Like Octanuclear Palladium Thiolate Complex
Authors: Yamashina Yukari , Kataoka Yasutaka , Ura Yasuyuki 
Published: July 2014

AbstractAn iodine molecule was successfully inserted into the inner cavity of a tiara‐like octanuclear palladium thiolate complex, [Pd(μ‐SCH2CO2Me)2]8. The included iodine molecule coordinated weakly to six palladium atoms in both linear and bent modes, as confirmed by X‐ray crystallography and DFT calculations. The inclusion complex reacted with an excess amount of I2 to produce a disulfide, which was accompanied by decomposition of the tiara ring.
2,5‐Diamide‐Substituted Five‐Membered Heterocycles: Challenging Molecular Synthons
Authors: Fabbro Chiara , Armani Simone , Carloni Laure‐Elie , De Leo Federica , Wouters Johan , Bonifazi Davide 
Published: July 2014

AbstractWe describe synthetic routes for preparing previously unknown 2,5‐diamide‐substituted five‐membered heterocycles based on the thiophene, pyrrole, and furan ring systems by exploiting Curtius‐like rearrangement reactions. Conformation analysis of the 2,5‐diamidothiophene derivatives identified a “closed” conformation, in which the two carbonyl O atoms are in close contact with the thiophene S atom.