bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimentelle und theoretische Untersuchungen zur katalytischen asymmetrischen 4π‐Elektrocyclisierung von N‐Heterocyclen
Authors: Raja Sadiya , Nakajima Masaki , Rueping Magnus 
Published: December 2014

AbstractDie erste asymmetrische metallkatalysierte Nazarov‐Cyclisierung von N‐Heterocyclen wurde entwickelt. Die Verwendung eines chiralen Katalysators ermöglicht die enantioselektive Elektrocyclisierung unter milden Bedingungen, wobei die Produkte in guten Ausbeuten und mit exzellenten Selektivitäten erhalten werden. Mittels Dichtefunktionalrechnungen werden der Reaktionsmechanismus und die absolute Konfiguration der erhaltenen Produkte erklärt.
Insulating or Metallic: Coexistence of Different Electronic Phases in Zinc Clusters
Authors: Aguado Andrés , Vega Andrés , Lebon Alexandre , von Issendorff Bernd 
Published: December 2014

AbstractHow many of the several attributes of the bulk metallic state persist in a nanoparticle containing a finite number of atoms of a metallic element? Do all those attributes emerge suddenly at a well‐defined cluster size or do they rather evolve at different rates and in a broad size range? These fundamental questions have been addressed through a conjoint experimental/theoretical investigation of zinc clusters. We report the observation of novel coexistence phenomena involving different electronic phases: for some sizes, metallic and insulating electronic states coexist within a single, Janus‐like, nanoparticle; for the rest of sizes, we report the coexistence of two weakly interacting metallic phases with different dimensionalities, localized at the shell and the core of the nanoparticle. These fascinating features are due to an anomalously long core–shell separation that equips the shell and core regions with largely independent structural, vibrational, and thermal properties.
Experimental and Computational Study of the Catalytic Asymmetric 4π‐Electrocyclization of N‐Heterocycles
Authors: Raja Sadiya , Nakajima Masaki , Rueping Magnus 
Published: December 2014

AbstractThe first asymmetric metal‐catalyzed Nazarov cyclization of N‐heterocycles has been developed. The use of a chiral catalyst allows the enantioselective electrocyclization of N‐heterocycles under mild conditions and the corresponding products are obtained in good yields with excellent enantio‐ and diastereoselectivity. The reaction mechanism and the absolute configuration of the obtained products are explained by means of computational studies.
Regiodivergent Addition of Phenols to Allylic Oxides: Control of 1,2‐ and 1,4‐Additions for Cyclitol Synthesis
Authors: Moschitto Matthew J. , Vaccarello David N. , Lewis Chad A. 
Published: December 2014

AbstractControl of 1,2‐ and 1,4‐addition of substituted phenols to allylic oxides is achieved by intercepting palladium π‐allyl complexes. The interconversion of palladium complexes results in the total synthesis of MK 7607, cyathiformine B type, streptol, and a new cyclitol.
Biomechanical Implications of Intraspecific Shape Variation in Chimpanzee Crania: Moving Toward an Integration of Geometric Morphometrics and Finite Element Analysis
Authors: Smith Amanda L. , Benazzi Stefano , Ledogar Justin A. , Tamvada Kelli , Pryor Smith Leslie C. , Weber Gerhard W. , Spencer Mark A. , Dechow Paul C. , Grosse Ian R. , Ross Callum F. , Richmond Brian G. , Wright Barth W. , Wang Qian , Byron Craig , Slice Dennis E. , Strait David S. 
Published: December 2014

ABSTRACTIn a broad range of evolutionary studies, an understanding of intraspecific variation is needed in order to contextualize and interpret the meaning of variation between species. However, mechanical analyses of primate crania using experimental or modeling methods typically encounter logistical constraints that force them to rely on data gathered from only one or a few individuals. This results in a lack of knowledge concerning the mechanical significance of intraspecific shape variation that limits our ability to infer the significance of interspecific differences. This study uses geometric morphometric methods (GM) and finite element analysis (FEA) to examine the biomechanical implications of shape variation in chimpanzee crania, thereby providing a comparative context in which to interpret shape‐related mechanical variation between hominin species. Six finite element models (FEMs) of chimpanzee crania were constructed from CT scans following shape‐space Principal Component Analysis (PCA) of a matrix of 709 Procrustes coordinates (digitized onto 21 specimens) to identify the individuals at the extremes of the first three principal components. The FEMs were assigned the material properties of bone and were loaded and constrained to simulate maximal bites on the P3 and M2. Resulting strains indicate that intraspecific cranial variation in morphology is associated with quantitatively high levels of variation in strain magnitudes, but qualitatively little variation in the distribution of strain concentrations. Thus, interspecific comparisons should include considerations of the spatial patterning of strains rather than focus only on their magnitudes. Anat Rec, 298:122–144, 2015. © 2014 Wiley Periodicals, Inc.
Three‐Dimensional Geometric Morphometric Analysis of the Nasopharyngeal Boundaries and Its Functional Integration with the Face and External Basicranium Among Extant Hominoids
Authors: Pagano Anthony S. , Laitman Jeffrey T. 
Published: December 2014

ABSTRACTThe nasopharynx is a centrally located but understudied upper respiratory tract component. This study tested hypotheses related to the functional integration of the nasopharyngeal boundaries with the facial skeleton and external basicranium over the course of development in humans and nonhuman hominoids. It was hypothesized that facial morphology (width, length, and kyphosis) is related to nasopharyngeal width and choanal morphology, whereas relative external basicranial proportions are related to nasopharyngeal depth. Human infants were used as models of extreme orthognathy and external basicranial retroflexion, whereas nonhuman hominoids were used to model greater relative prognathism and external basicranial retroflexion. Both of these groups were contrasted against adult humans, who exhibit both extreme orthognathy and external basicranial flexion. Three‐dimensional landmark coordinate data were collected from age‐graded series of Homo, Pan, Gorilla, Pongo, and Hylobates. Generalized Procrustes Analysis was performed, and multivariate shape differences were evaluated via principal components analysis. Additionally, linear measures were extracted from the Procrustes‐corrected sets of landmark data. Results indicate that human adults are indeed distinct from all groups in possessing a relatively shallow nasopharyngeal roof and shorter, more flexed external basicranial axis. Human adults and infants both exhibit greater relative choanal and nasopharyngeal width. Nonhuman hominoid faces tended to become airorhynch into adulthood, whereas humans exhibited the opposite trend. When pooling all the hominoids, facial width and palate length were strongly correlated with choanal and nasopharyngeal width, whereas facial kyphosis was strongly correlated with choanal orientation. The hypotheses were supported as the results indicated a morphologic relationship among nasopharyngeal boundaries, the facial skeleton, and the external basicranium. Anat Rec, 298:85–106, 2015. © 2014 Wiley Periodicals, Inc.
Brief Report: Methotrexate Prevents Wear Particle–Induced Inflammatory Osteolysis in Mice Via Activation of Adenosine A2A Receptor
Authors: Mediero Aránzazu , Perez‐Aso Miguel , Wilder Tuere , Cronstein Bruce N. 
Published: December 2014

ObjectiveAdenosine, acting at the A2A receptor, mediates the antiinflammatory effects of methotrexate (MTX) in models of inflammation. We previously reported that A2A receptor ligation diminishes wear particle–driven osteolysis. The aim of this study was to investigate whether MTX treatment could prevent bone resorption caused by inflammatory osteolysis.MethodsC57BL/6 mice (6–8 weeks old) received intraperitoneal injections of 1 mg/kg MTX (n = 20) or 0.9% saline (n = 10), starting 2 weeks prior to surgical implantation of 3 mg of wear particles (ultrahigh molecular weight polyethylene [UHMWPE] particles). The MTX‐treated mice received daily injections of vehicle or ZM241385 at the surgical site until they were killed, 14 days later. XenoLight RediJect Bone Probe 680 was injected intravenously, and fluorescence analysis of the calvaria using an IVIS imaging system was performed to assess bone formation. Micro–computed tomography (micro‐CT) and immunostaining for osteoclast and osteoblast markers were performed.ResultsImplantation of wear particles induced bone pitting and thinning, as shown by micro‐CT. MTX treatment markedly reduced osteolysis, and this effect was abrogated by treatment with the A2A receptor antagonist ZM241385. Implantation of UHMWPE reduced new bone formation, and MTX treatment restored new bone formation, an effect that was completely reversed by treatment with ZM241385. Histologic examination of particle‐exposed calvariae demonstrated that MTX prevented accumulation of an inflammatory infiltrate at the site of particle implantation, increased the number of osteoblasts, and reduced the number of osteoclasts at the site of inflammation, an effect that was reversed by treatment with ZM241385.ConclusionMTX reduces inflammatory osteolysis indirectly via stimulation of A2A receptor and may represent a novel approach to enhance orthopedic implant survival, delaying or eliminating the need for revision arthroplasty surgery.
Simultaneous Genotyping of Multiple Somatic Mutations by Using a Clamping PNA and PNA Detection Probes
Authors: Kim Yong‐Tae , Kim Jin Woo , Kim Sung Kee , Joe Goon Ho , Hong In Seok 
Published: December 2014

AbstractIt has been very difficult to detect and quantify multiple somatic mutations simultaneously in single‐tube qPCR. Here, a novel method for simultaneous detection of multiple mutations and a melting curve analysis was developed by using clamping PNA and detection PNA probes. Each PNA probe was designed to have a specific melting temperature by the introduction of γ‐PNA monomer. This technique was successfully applied to the detection of six genotypes in two different mutations of K‐RAS at the same time. Such simultaneous analysis of an amplified curve and a melting curve in qPCR can be widely used for the early diagnosis of cancer and determining the prognosis of drug treatments.
Influence of Design Parameters on Hydrodynamics and Heat Transfer of a Modularized Millireactor
Authors: Biessey Philip , Grünewald Marcus 
Published: December 2014

AbstractAn apparatus with rectangular product channels and static mixing elements for process intensification is investigated in terms of heat transfer and hydrodynamics. Herringbone‐like static mixing elements increase the overall heat transfer coefficient significantly, and the stall angle was found to have a major influence on hydrodynamics and heat transfer. The knowledge of structural parameters of the mixing elements is crucial for apparatus design and prediction of the apparatus performance. A method to derive mean structural parameters from experimental results is presented.
A Series of π‐Extended Thiadiazoles Fused with Electron‐Donating Heteroaromatic Moieties: Synthesis, Properties, and Polymorphic Crystals
Authors: Kato Shin‐ichiro , Furuya Takayuki , Nitani Masashi , Hasebe Naoya , Ie Yutaka , Aso Yoshio , Yoshihara Toshitada , Tobita Seiji , Nakamura Yosuke 
Published: December 2014

Abstractπ‐Extended thiadiazoles 4–8 fused with various electron‐donating heteroaromatic moieties have been designed and synthesized. Just like thiadiazoles 1–3 synthesized previously, 4–8 exhibit intramolecular charge‐transfer (CT) interactions, moderate‐to‐good fluorescence quantum yields of up to 0.78, and electrochemical amphoterism. In comparison with 1–3, the benzannulation in thiadiazoles 4–7 moderately extends the π conjugation and significantly increases the stability of the cationic species formed upon electrochemical oxidation. The fluorescence quantum yields increase remarkably from 3 to 6 and 7 due to the efficient suppression of nonradiative intersystem crossing resulting from the benzannulation. The properties of 4–8 strongly reflect the different species annulated to the pyrrole rings, namely benzothiophene, naphthalene, and benzofuran. Eleven crystals, including poly‐ and pseudopolymorphic crystals of 1 (1‐Crys.(Y) and 1‐Crys.(G)), 2 (2‐Crys.(O) and 2‐Crys.(G)), 4 (4‐Crys.(O) and 4‐Crys.(G)), and 6 (6‐Crys.(O) and 6‐Crys.(G)), were obtained and characterized by X‐ray crystallography. The fluorescence colors and efficiencies are distinct for each poly‐ and pseudopolymorph of 1, 2, 4, and 6. It has been suggested that both the extent of the electronic interactions in the π‐stacked dimers and the presence of excitonic interactions originating in the 1D face‐to‐face slipped columns affect the fluorescence wavelengths of the poly‐ and pseudopolymorphs.
Mechanism of [3+2] Cycloaddition of Alkynes to the [Mo3S4(acac)3(py)3][PF6] Cluster
Authors: Pino‐Chamorro Jose Ángel , Gushchin Artem L. , Fernández‐Trujillo M. Jesús , Hernández‐Molina Rita , Vicent Cristian , Algarra Andrés G. , Basallote Manuel G. 
Published: December 2014

AbstractA study, involving kinetic measurements on the stopped‐flow and conventional UV/Vis timescales, ESI‐MS, NMR spectroscopy and DFT calculations, has been carried out to understand the mechanism of the reaction of [Mo3S4(acac)3(py)3][PF6] ([1]PF6; acac=acetylacetonate, py=pyridine) with two RCCR alkynes (R=CH2OH (btd), COOH (adc)) in CH3CN. Both reactions show polyphasic kinetics, but experimental and computational data indicate that alkyne activation occurs in a single kinetic step through a concerted mechanism similar to that of organic [3+2] cycloaddition reactions, in this case through the interaction with one Mo(μ‐S)2 moiety of [1]+. The rate of this step is three orders of magnitude faster for adc than that for btd, and the products initially formed evolve in subsequent steps into compounds that result from substitution of py ligands or from reorganization to give species with different structures. Activation strain analysis of the [3+2] cycloaddition step reveals that the deformation of the two reactants has a small contribution to the difference in the computed activation barriers, which is mainly associated with the change in the extent of their interaction at the transition‐state structures. Subsequent frontier molecular orbital analysis shows that the carboxylic acid substituents on adc stabilize its HOMO and LUMO orbitals with respect to those on btd due to better electron‐withdrawing properties. As a result, the frontier molecular orbitals of the cluster and alkyne become closer in energy; this allows a stronger interaction.
Functionalization of Hydride‐Terminated Photoluminescent Silicon Nanocrystals with Organolithium Reagents
Authors: Höhlein Ignaz M. D. , Angı Arzu , Sinelnikov Regina , Veinot Jonathan G. C. , Rieger Bernhard 
Published: December 2014

AbstractHydride‐terminated photoluminescent silicon nanocrystals (SiNCs) were functionalized with organolithium compounds. The reaction is proposed to proceed through cleavage of SiSi bonds and formation of a SiLi surface species. The method yields colloidally stabilized SiNCs at room temperature with short reaction times. SiNCs with mixed surface functionalities can be prepared in an easy two‐step reaction by this method by quenching of the SiLi group with electrophiles or by addressing free SiH groups on the surface with a hydrosilylation reaction.
Quantum Size Effects in the Size–Temperature Phase Diagram of Gallium: Structural Characterization of Shape‐Shifting Clusters
Authors: Steenbergen Krista G. , Gaston Nicola 
Published: December 2014

AbstractFinite temperature analysis of cluster structures is used to identify signatures of the low‐temperature polymorphs of gallium, based on the results of first‐principle Born–Oppenheimer molecular dynamics simulations. Pre‐melting structural transitions proceed from either the β‐ and/or the δ‐phase to the γ‐ or δ‐phase, with a size‐ dependent phase progression. We relate the stability of each isomer to the electronic structures of the different phases, giving new insight into the origin of polymorphism in this complicated element.
Single Crystal‐to‐Single Crystal Site‐Selective Postsynthetic Metal Exchange in a Zn–MOF Based on Semi‐Rigid Tricarboxylic Acid and Access to Bimetallic MOFs
Authors: Bajpai Alankriti , Chandrasekhar Pujari , Govardhan Savitha , Banerjee Rahul , Moorthy Jarugu Narasimha 
Published: December 2014

AbstractThe metal ions in a neutral Zn–MOF constructed from tritopic triacid H3L with inherent concave features, rigid core, and peripheral flexibility are found to exist in two distinct SBUs, that is, 0D and 1D. This has allowed site‐selective postsynthetic metal exchange (PSME) to be investigated and reactivities of the metal ions in two different environments in coordination polymers to be contrasted for the first time. Site‐selective transmetalation of Zn ions in the discrete environment is shown to occur in a single crystal‐to‐single crystal (SCSC) fashion, with metal ions such as Fe3+, Ru3+, Cu2+, Co2+, etc., whereas those that are part of 1D SBU sustain structural integrity, leading to novel bimetallic MOFs, which are inaccessible by conventional approaches. To the best of our knowledge, site‐selective postsynthetic exchange of an intraframework metal ion in a MOF that contains metal ions in discrete as well as polymeric SBUs is heretofore unprecedented.
A Facile Route to Backbone‐Tethered N‐Heterocyclic Carbene (NHC) Ligands via NHC to aNHC Rearrangement in NHC Silicon Halide Adducts
Authors: Schneider Heidi , Schmidt David , Radius Udo 
Published: December 2014

AbstractThe reaction of 1,3‐diisopropylimidazolin‐2‐ylidene (iPr2Im) with diphenyldichlorosilane (Ph2SiCl2) leads to the adduct (iPr2Im)SiCl2Ph2 1. Prolonged heating of isolated 1 at 66 °C in THF affords the backbone‐tethered bis(imidazolium) salt [(aHiPr2Im)2SiPh2]2+ 2 Cl− 2 (“a” denotes “abnormal” coordination of the NHC), which can be synthesized in high yields in one step starting from two equivalents of iPr2Im and Ph2SiCl2. Imidazolium salt 2 can be deprotonated in THF at room temperature using sodium hydride as a base and catalytic amounts of sodium tert‐butoxide to give the stable N‐heterocyclic dicarbene (aiPr2Im)2SiPh2 3, in which two NHCs are backbone‐tethered with a SiPh2 group. This easy‐to‐synthesize dicarbene 3 can be used as a novel ligand type in transition metal chemistry for the preparation of dinuclear NHC complexes, as exemplified by the synthesis of the homodinuclear copper(I) complex [{a(ClCuiPr2Im)}2SiPh2] 4.
ChemInform Abstract: An Azide‐Bridged Copper(II) Complex: Poly[piperazine‐1,4‐dium [Tetra‐μ3‐azido‐ϰ12N1:N 1:N1‐hexa‐μ2‐azido‐ϰ 12N1:N1‐di‐μ2 ‐azido‐ϰ4N1:N3‐pentacopper(II)] Tetrahydrate].
Authors: Liu Hou‐Ting , Lu Jing 
Published: December 2014

AbstractCrystals of the title compound {(H2pip) [Cu5(N3)12] ·4H2O}n (pip: piperazine) are synthesized by slow diffusion between an aq.
ChemInform Abstract: Bi2Pt(hP9) by Low‐Temperature Reduction of Bi13Pt3I7: Reinvestigation of the Crystal Structure and Chemical Bonding Analysis.
Authors: Kaiser Martin , Baranov Alexey I. , Ruck Michael 
Published: December 2014

AbstractBi2Pt(hP9) or γ‐Bi2Pt is a high‐temperature modification which is metastable below 420 °C.
ChemInform Abstract: Synthesis, Crystal and Electronic Structure of the Sulfido Ferrate Oxide, Cs11[Fe5S8]2[O].
Authors: Schwarz Michael , Roehr Caroline 
Published: December 2014

AbstractCs11[Fe5S8]2[O] is prepared by heating a mixture of Fe, Cs2S2, and CsO2 or Fe2O3 as O source (corundum crucible, 1170 K, 12 h; cooling rate of 20 K/h).
ChemInform Abstract: Dihydrogen Tetrametaphosphate, [P4O12H2]2—: Synthesis, Solubilization in Organic Media, Preparation of Its Anhydride [P4O11]2— and Acidic Methyl Ester, and Conversion to Tetrametaphosphate Metal Complexes via Protonolysis.
Authors: Jiang Yanfeng , Chakarawet Khetpakorn , Kohout Andrea Laura , Nava Matthew , Marino Nadia , Cummins Christopher C. 
Published: December 2014

AbstractThe strong Broensted acid [P4O12H2]2‐ serves as precursor to numerous derivatives.
ChemInform Abstract: First Polymeric Polyphosphide via Solution Chemistry — Synthesis and Crystal Structure of CsP7.
Authors: Meier Martin , Faupel Victoria , Korber Nikolaus 
Published: December 2014

AbstractCsP7 is prepared via a solution reaction of Cs3P11 and Te (molar ratio of 2:1) in liquid NH3 (195 K, storage for several weeks at 235 K).
ChemInform Abstract: An Acentric Calcium Borate Ca2[B5O9]·(OH)·H2O: Synthesis, Structure, and Nonliner Optical Property.
Authors: Wei Qi , Cheng Jian‐Wen , He Chao , Yang Guo‐Yu 
Published: December 2014

AbstractThe title compound is solvothermally synthesized from mixtures of Ca(OH)2, H3BO3, and Li2CO3 using pyridine and water as mixed solvent (autoclave, 230 °C, 6 d, 80% yield).
ChemInform Abstract: All‐Inorganic Networks and Tetramer Based on Tin(II)‐Containing Polyoxometalates: Tuning Structural and Spectral Properties with Lone‐Pairs.
Authors: Zhao Chongchao , Glass Elliot N. , Chica Bryant , Musaev Djamaladdin G. , Sumliner Jordan M. , Dyer R. Brian , Lian Tianquan , Hill Craig L. 
Published: December 2014

AbstractStructural and spectral features of Sn(II)‐containing polyoxometalate networks (IVa, b) and the molecular compound (VI) are investigated by XRD, Raman and UV/VIS spectroscopy, electrochemical measurements, and DFT calculations.
ChemInform Abstract: Chlorosulfonamide Salts Are Superior Electrophilic Chlorine Precursors for the Organocatalytic Asymmetric Chlorocyclization of Unsaturated Amides.
Authors: Jaganathan Arvind , Borhan Babak 
Published: December 2014

AbstractChloramine‐T is used as an inexpensive precursor of electrophilic chloride to produce asymmetric chlorocyclization of N‐allylic substituted aroylamides.
ChemInform Abstract: Catalytic, Formal Homo‐Nazarov‐Type Cyclizations of Alkylidene Cyclopropane‐1,1‐ketoesters: Access to Functionalized Arenes and Heteroaromatics.
Authors: Aponte‐Guzman Joel , Taylor J. Evans , Tillman Elayna , France Stefan 
Published: December 2014

AbstractThe outcome of the title reaction depends on the alkylidene substituents of the substrates.
ChemInform Abstract: The Reaction of Cyanamidium Salts with Ylidenecyanamide Derivatives.
Authors: Abu‐El‐Halawa Rajab , Zabin Sami A. , Al‐Refai Mahmoud , Ibrahim Mohammad , Kaimari Tawfeq , Mueller Thomas J. J. 
Published: December 2014

AbstractConjugated iminium salts (III) and (V) are obtained by ene reaction of cyanamidium salt (I) with ylidenecyanamide derivatives (II) and (IV), respectively.
ChemInform Abstract: CuI‐Catalyzed Cross‐Coupling of Terminal Alkynes with Dialkoxycarbenes: A General Method for the Synthesis of Unsymmetrical Propargylic Acetals.
Authors: Xiao Tiebo , Zhang Ping , Xie Yang , Wang Jun , Zhou Lei 
Published: December 2014

AbstractOxadiazolines (I) can be generally employed as a source of dialkoxycarbenes generated by thermal decomposition.
ChemInform Abstract: Synthesis of N‐(α‐Fluorovinyl)azoles by the Reaction of Difluoroalkenes with Azoles.
Authors: Xiong Yang , Zhang Xuxue , Huang Tao , Cao Song 
Published: December 2014

AbstractA slight excess (1.2 equiv.) of difluoroalkene reacts with various N‐heterocycles to afford monosubstituted (E)‐configurated products.
ChemInform Abstract: Cinchona—Diaminomethylenemalononitrile Organocatalyst for Asymmetric Conjugate Addition of 1,3‐Diketone to Nitroalkene.
Authors: Miura Tsuyoshi , et al. et al. 
Published: December 2014

AbstractThe conjugate addition of acetylacetone to various nitroalkenes in the presence of a diaminomethylenemalononitrile substituted cinchona catalyst gives the corresponding addition products in good to excellent yields with up to 89% ee.