bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards Molecular Conductors with a Spin‐Crossover Phenomenon:Crystal Structures, Magnetic Properties and Mössbauer Spectra of[Fe(salten)Mepepy][M(dmit)2] Complexes
Authors: Faulmann Christophe , Dorbes Stéphane , Garreau de Bonneval Bénédicte , Molnár Gábor , Bousseksou Azzedine , Gomez‐Garcia Carlos J. , Coronado Eugenio , Valade Lydie 
Published: July 2005

AbstractThree new iron(III) compounds of formula [Fe(salten)Mepepy][M(dmit)2]·CH3CN (M = Ni, Pd, Pt; H2salten = 4‐azaheptamethylene‐1,7‐bis(salicylideneiminate); Mepepy = 1‐(pyridin‐4‐yl)‐2‐(N‐methylpyrrol‐2‐yl) ethane; dmit2– = 1,3‐dithiole‐2‐thione‐4,5‐dithiolato) have been synthesised and the crystal structure of each compound has been solved at different temperatures. The structures consist of alternating layers of [M(dmit)2]– units and [Fe(salten)Mepepy] cations. In the Ni compound photo‐isomerisation of the Mepepy ligand can be observed in dichloromethane solution. The temperature dependence of the magnetic susceptibility of the compounds reveals a gradual S = 5/2 blabla S = 1/2 spin crossover of the FeIII ions. This phenomenon is confirmed by Mössbauer spectroscopy for the Ni compound, which also reveals a magnetic component at 4.5 K with a hyperfine magnetic field, Hi, of 442(3) Oe. Theoretical analysis of the thermal variation of the high‐spin proportion allows us to calculate the thermodynamical parameters of the spin‐crossover behaviour in this compound: energy‐gap (Δ) = 1536 cm–1, entropy change (ΔS) = 33 J K–1 mol–1 and a cooperative interaction, J, of 0 cm–1 (non‐cooperative spin crossover). The fractional oxidation state complex [Fe(salten)Mepepy][Ni(dmit)2]3 has been obtained after electrooxidation of [Fe(salten)Mepepy][Ni(dmit)2] in acetonitrile. It exhibits a gradual spin conversion coupled with antiferromagnetic interactions. Its room temperature electrical conductivity is 0.1 S cm–1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Periodates of Tetravalent Titanium, Zirconium, Hafnium and Thorium: Synthesis, Characterisation and EXAFS Study
Authors: Hector Andrew L. , Levason William 
Published: July 2005

AbstractReaction of TiO(SO4)·xH2O with periodic acid in aqueous solution at pH = 2 yields a precipitate of Ti2O2HIO6·5H2O, while reaction of zirconyl, hafnyl or thorium nitrate with periodic acid in hot aqueous nitric acid solutions yields MHIO6·xH2O (M = Zr, Hf, Th; x = 4 or 5). The thorium periodate is soluble in aqueous KOH and KThIO6·4H2O can be precipitated from these solutions. The zirconium, hafnium and both thorium periodates are shown by EXAFS to consist of edge‐sharing chains of MO8 and IO6 units, IR and Raman studies indicate protonation of periodate in the MHIO6 modifications. The titanium periodate contains vertex‐sharing IO6 groups. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The Electronic Interaction Between Au55(PPh3)12Cl6 Monolayers Through SiO2 Films
Authors: Neumeier Stefan , Reuter Torsten , Schmid Günter 
Published: July 2005

AbstractAu55(PPh3)12Cl6 monolayers embedded between 5‐nm SiO2 barrier films have been successfully generated. The cluster monolayers were obtained by spin coating of very dilute solutions. The SiO2 films were prepared by means of a special anodic plasma arc technique. Systems of one up to eight cluster/SiO2 combinations on a gold surface have been generated and investigated. In the voltage region between –5 and +5 mV, all samples exhibited linear current‐voltage characteristics. Control samples with only SiO2 show very different I‐U behaviour. We interpret the behaviour observed as a result of electronic tunnelling from the cluster monolayers through the SiO2 barrier films. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Suzuki Reactions with Stable Organic Radicals – Synthesis of Biphenyls Substituted with Nitronyl‐Nitroxide Radicals
Authors: Stroh Christophe , Mayor Marcel , von Hänisch Carsten 
Published: July 2005

AbstractThe synthesis of biphenyls substituted with nitronyl‐nitroxide organic radicals is described. To investigate the Suzuki‐type cross‐coupling reaction conditions in the presence of the radical, a model compound 1 was prepared. The successful coupling was extended to cyano‐functionalized, biphenylic, paramagnetic molecules. Both the ortho‐ and meta‐iodophenyl‐nitronyl‐nitroxide radicals were used to synthesize radicals 2 and 3. The characterizations of the spin‐labelled molecules obtained by this synthetic strategy include two X‐ray crystal structures and magnetic measurements. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Perylene–Oligothiophene–Perylene Triads for Photovoltaic Applications
Authors: Cremer Jens , Bäuerle Peter 
Published: July 2005

AbstractA series of novel acceptor–donor–acceptor triad systems, consisting of head‐to‐tail‐coupled oligo(3‐hexylthiophene)s integrated between two terminal perylenemonoimides are described. These hybrid molecules, which differ by the length of the oligothiophene units from a quaterthiophene up to a dodecithiophene were synthesized by an effective palladium‐catalyzed Ullmann‐type homo‐coupling reaction in good yields. The optical and electrochemical properties of these compounds were determined, and on the basis of this series structure‐property relationships have been established which provide vital information for the fabrication of the corresponding photovoltaic devices. Because the synthesized perylenyl‐oligothiophenes distinguish themselves by a high absorption between 300 and 550 nm and an almost complete fluorescence quenching of the perylene acceptor, they meet the requirements for organic solar cells. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Theoretical Study on the Reactivity and Regioselectivity of the Ene Reaction of 1Δg O2 with α,β‐Unsaturated Carbonyl Compounds
Authors: Maranzana Andrea , Canepa Carlo , Ghigo Giovanni , Tonachini Glauco 
Published: July 2005

AbstractThe ene reaction of singlet oxygen with α,β‐unsaturated carbonyl compounds gives unsaturated hydroperoxides and displays interesting features: Different reactivities of the s‐cis and s‐trans reactants and a marked regioselectivity, influenced to some extent by solvent polarity. All of these traits are accounted for by a polar diradical mechanism. A perepoxide intermediate is not a critical point on the reaction’s potential energy surface. Also, a trioxene intermediate is located too high in energy to be significantly populated. An alternative pathway leading to dioxetane is not as effective as the ene pathway giving the hydroperoxide. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Palladium‐Catalyzed C–S Bond Formation: Rate and Mechanism of the Coupling of Aryl or Vinyl Halides with a Thiol Derived from a Cysteine
Authors: Moreau Xavier , Campagne Jean Marc , Meyer Gilbert , Jutand Anny 
Published: July 2005

AbstractThe mechanism of the palladium‐catalyzed coupling reaction of aryl or vinyl halides with a thiol derived from a protected chiral cysteine 1 (RSH), leading to C–S bond formation, has been investigated in the context of catalytic reactions. All palladium complexes involved in the catalytic cycle have been characterized, successively, as PhPdI(dppf), PhPdI(SHR)(η1‐dppf) and PhPd(SR)(dppf). The oxidative addition reaction which generates PhPdI(dppf) is followed by the metallation of 1 whose mechanism has been investigated. In the case of the weakly acidic cysteine 1 (RSH) studied here, the anions RS– are not generated in detectable concentrations in the reaction with the NEt3 base. Even if the classical transmetallation reaction of PhPdI(dppf) by RS–, present at a very low concentration, cannot be entirely excluded, we propose that an alternative mechanism, complexation of the thiol, leads to the previously unreported PhPdI(SHR)(η1‐dppf) (observed by 31P NMR spectroscopy) after decomplexation of one of the phosphorus atoms of the dppf ligand, followed by the easier deprotonation of the coordinated RSH by the base, which generates PhPd(SR)(dppf). A classical reductive elimination reaction delivers the coupling product PhSR. The kinetics of all the steps have been investigated independently, one after the other, starting from Pd2(dba)3 and dppf, using the initial concentrations of the reagents used in the catalytic reaction. Under the experimental conditions used in the catalytic reaction involving phenyl iodide and NEt3 as the base, the reductive elimination reaction is the slowest step which mainly limits the rate of the catalytic cycle up to approximately 80 % conversion. The metallation reaction of RSH is very slow when propylene oxide was used as the probase. The reductive elimination is the slowest step in the cross‐coupling of a vinyl iodide. Diastereoisomers of the vinyl‐PdX(dppf) (X = I, SR) complexes were observed as a result of the atropisomerism induced by the bulkiness of the investigated vinyl group and the chiral center present on the vinyl or on the SR group. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Dithioacetals as Zwitterion Synthons
Authors: Luh Tien‐Yau , Lee Chin‐Fa 
Published: July 2005

AbstractThis microreview highlights recent advances in the synthetic applications of dithioacetal functionality. Propargylic dithioacetals and related compounds have been shown to be useful, with the aid of thiophilic organolithium or organocopper reagents, for the synthesis of polysubstituted allenes, trisubstituted furans, and pyrroles. An extension of this annulation reaction to the bidirectional iterative synthesis of furan‐containing oligoaryls and to cyclophane synthesis is described. Alternatively, the convergent synthesis of such oligoaryls from propargylic dithioacetals is briefly discussed. Not only can the carbon–sulfur bonds in dithioacetals be readily displaced by carbon–carbon and/or carbon–heteroatom bonds, but in addition a range of reactions involving polarity inversion in neighboring carbon atoms can also take place. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
New Polymer‐Supported Organosilicon Reagents
Authors: Fauvel Anne , Deleuze Hervé , Landais Yannick 
Published: July 2005

AbstractNew polymer‐supported organosilanes have been prepared using two different strategies. These involved the synthesis of soluble and insoluble supports through the copolymerization of styrene and monomers containing a thiophene ring. Selective metallation of the thiophene ring followed by silylation allowed the introduction of various functionalized organosilanes onto the polymer with a high degree of substitution. These supports can be used for solid‐phase organic synthesis, the product being released through a Tamao–Fleming oxidation, which generates an additional hydroxy group during the cleavage along with the recycled support. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Restricted Rotation in (Phenylpyrrolidino)fullerene Derivatives
Authors: Ajamaa Fettah , Figueira Duarte Teresa M. , Bourgogne Cyril , Holler Michel , Fowler Patrick W. , Nierengarten Jean‐François 
Published: July 2005

AbstractA complete series of (phenylpyrrolidino)fullerene derivatives has been prepared. A detailed conformational analysis of these compounds has been carried out by variable‐temperature 1H NMR experiments and computational studies. In the case of (phenylpyrrolidino)fullerene derivatives without ortho substituents, dynamic phenomena arising from restricted rotation around the phenyl–pyrrolidine bond are observed. In contrast, as soon as one of the ortho positions of the phenyl ring is substituted, the rotational energy barrier is high enough to prevent observation under our experimental conditions (room temperature to 120 °C) of any dynamic exchange resulting from rotation of the phenyl substituent on the pyrrolidine ring. Whereas, in principle, two diastereoisomeric conformers can exist for the ortho‐substituted (phenylpyrrolidino)fullerenes, only the atropisomers in which the unsubstituted ortho position is located atop the fullerene sphere are obtained. We conclude that the reaction of the ortho‐substituted benzaldehyde derivatives with C60 is diastereoselective, affording only one of the two possible atropisomers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Microwave‐Assisted Organic Synthesis in Near‐Critical Water at 300 °C –A Proof‐of‐Concept Study
Authors: Kremsner Jennifer M. , Kappe C. Oliver 
Published: July 2005

AbstractMicrowave‐assisted organic synthesis in near‐critical water (NCW) in the 270–300 °C temperature range has been investigated in a dedicated multimode microwave reactor utilizing heavy‐walled quartz reaction vessels. Several different known transformations such as the hydrolysis of esters or amides, the hydration of alkynes, Diels–Alder cycloadditions, pinacol rearrangements, and the Fischer indole synthesis were successfully performed in microwave‐generated NCW without the addition of an acid or base catalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of a Novel Series of 6,6'‐Disubstituted 4,4'‐Bipyrimidines by Radical Anion Coupling: New π‐Accepting Ligands for Coordination Chemistry
Authors: Ioachim Elena , Medlycott Elaine A. , Polson Matthew I. J. , Hanan Garry S. 
Published: July 2005

AbstractA new family of 6,6'‐disubstituted 4,4'‐bipyrimidine ligands has been prepared and characterized. The reduction potentials of the new ligands, as determined by cyclic voltammetry, indicate that these new ligands are considerably better π‐acceptors than the ubiquitous 2,2'‐bipyridine ligand, and are even superior to the parent unsubstituted 4,4'‐bipyrimidine ligand. The substituents in 6,6' positions of the 4,4'‐bipyrimidine also cause a red‐shift in the π→π* and n→π* absorptions throughout the UV region. The X‐ray crystal structure of one member of the family of bipyrimidines demonstrates that the aryl substituents may lie coplanar with the pyrimidine rings in the solid state. The additional electron delocalization afforded by the aryl substituents on the pyrimidine rings contribute to the better π‐accepting ability of these compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The reality of unreal situations: Caveats and insights
Authors: Alkin Marvin C. , Christie Christina A. , Greene Jennifer C. , Henry Gary T. , Donaldson Stewart I. , King Jean A. 
Published: July 2005

AbstractThe editors give each of the theorists a chance to respond to questions posed about the context of the situation in relation to their own experience in the field, exploring how the exercise had an impact on their evaluation designs.
Sol‐gel‐modified titanium with hydroxyapatite thin films and effect on osteoblast‐like cell responses
Authors: Kim Hae‐Won , Kim Hyoun‐Ee , Salih Vehid , Knowles Jonathan C. 
Published: July 2005

AbstractTitanium (Ti) surface was coated with hydroxyapatite (HA) films via the sol‐gel method. The coating properties, such as crystallinity and surface roughness, were controlled and their effects on the osteoblast‐like cell responses were investigated. The film crystallinity was controlled with different heat treatment temperatures (400, 500, and 600°C): Also the surface roughness was changed by using different heating rates (1 and 50°C/min). The obtained sol‐gel films had a dense and homogeneous structure with a thickness about 1 μm. The film heat‐treated at higher temperature had enhanced crystallinity (600 > 500 ≫ 400°C), while retaining similar surface roughness. When heat‐treated rapidly (50°C/min), the film became quite rough, with roughness parameters being much higher (4–6 times) than that obtained at a low heating rate (1°C/min). The dissolution rate of the film decreased with increasing crystallinity (400 ≫ 500 > 600°C), and the rougher film had slightly higher dissolution rate. The attachment, proliferation, and differentiation behaviors of human osteosarcoma HOS TE85 cells were affected by the properties of the films. On the films with higher crystallinity (heat treated over 500°C), the cells attached and proliferated well and expressed alkaline phosphatase (ALP) and osteocalcin (OC) to a higher degree as compared to the poorly crystallized film (heat treated at 400°C). On the rough film, the cell attachment was enhanced, but the ALP and OC expression levels were similar as compared to the smooth films. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Novel chitosan‐based hyaluronan hybrid polymer fibers as a scaffold in ligament tissue engineering
Authors: Funakoshi Tadanao , Majima Tokifumi , Iwasaki Norimasa , Yamane Shintaro , Masuko Tatsuya , Minami Akio , Harada Kazuo , Tamura Hiroshi , Tokura Seiichi , Nishimura Shin‐Ichiro 
Published: July 2005

AbstractTo clarify the feasibility of using novel chitosan‐based hyaluronan hybrid polymer fibers as a scaffold in ligament tissue engineering, their mechanical properties and ability to promote cellular adhesion, proliferation, and extracellular matrix production were studied in vitro. Chitosan fibers and chitosan‐based 0.05% and 0.1% hyaluronan hybrid fibers were developed by the wet spinning method. Hyaluronan coating significantly increased mechanical properties, compared to the chitosan fibers. Rabbit fibroblasts adhesion onto hybrid fibers was significantly greater than for the control and chitosan fibers. For analysis of cell proliferation and extracellular matrix production, a three‐dimensional scaffold was created by simply piling up each fiber. At 1 day after cultivation, the DNA content in the hybrid scaffolds was higher than that in the chitosan scaffold. Scanning electron microscopy showed that the fibroblasts had produced collagen fibers after 14 days of culture. Immunostaining for type I collagen was clearly predominant in the hybrid scaffolds, and the mRNA level of type I collagen in the hybrid scaffolds were significantly greater than that in the chitosan scaffold. The present study revealed that hyaluronan hybridization with chitosan fibers enhanced fiber mechanical properties and in vitro biological effects on the cultured fibroblasts. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Estrogen provides neuroprotection against activated microglia‐induced dopaminergic neuronal injury through both estrogen receptor‐α and estrogen receptor‐β in microglia
Authors: Liu Xuan , Fan Xiao‐Lan , Zhao Yan , Luo Guang‐Rui , Li Xu‐Ping , Li Rui , Le Wei‐Dong 
Published: July 2005

AbstractEstrogen provides neuroprotection against neurodegenerative diseases, including Parkinson's disease. Its effects may stem from interactions with neurons, astrocytes, and microglia. We demonstrate here in primary cultures of rat mesencephalic neurons that estrogen protects them from injury induced by conditioned medium obtained from lipopolysaccharide (LPS)‐activated microglia. LPS‐induced nitrite production and tumor necrosis factor‐α up‐regulation in microglia were blocked by estrogen pretreatment. Estrogen neuroprotection was related to microglial activation of estrogen receptors (ERs), insofar as the protective effect of the microglia‐conditioned medium was overridden by pretreatment of microglia with the ER antagonist ICI 182,780. On the other hand, the specific ERα antagonist, MPP dihydrochloride, only partially blocked the effects of estrogen, suggesting that estrogen protection was mediated via both ERα and ERβ. LPS treatment did not change ERα mRNA levels in microglia, astrocytes, and neurons, but it up‐regulated ERβ mRNA levels in microglia and astrocytes. Similarly, increased ERβ protein levels were detected in LPS‐activated microglia. More interesting was that immunocytochemical analysis revealed that ERβ was localized in the cytoplasm of microglia and in the cell nucleus of astrocytes and neurons. In summary, our results support the notion that estrogen inhibits microglial activation and thus exhibits neuroprotective effects through both ERα and ERβ activation. The cytoplasm location of microglial ERβ suggests the possible involvement of nonclassical effects of estrogen on microglia. Changes in microglial ERβ expression levels may modulate such effects of estrogen. © 2005 Wiley‐Liss, Inc.
A continuum mechanics‐based framework for optimizing boundary and finite element meshes associated with underground excavations‐framework
Authors: Zsáki Attila M. , Curran John H. 
Published: July 2005

AbstractMany field problems, from stress analysis, heat transfer to contaminant transport, deal with disturbances in a continuum caused by a ‘source’ (defined by its discrete geometry) and a ‘region of interest’ (where a solution is sought). Depending on the location of ‘regions of interest’ in relation to the ‘sources’, the level of geometric detail necessary to represent the ‘sources’ in a model can vary considerably. A practical application of stress analysis in mining is the evaluation of the effects of continuous excavation on the states of stress around mine openings. Labour intensive model preparation and lengthy computation coupled with the interpretation of analysis results can have considerable impact on the successful operation of an underground mine, where stope failures can cost tens of millions of dollars and possibly lead to closure of the mine.A framework is proposed based on continuum mechanics principles to automatically optimize the level of geometric detail required for an analysis by simplifying the model geometry using expanded and modified algorithms that originated in computer graphics. This reduction in model size directly translates to savings in computational time. The results obtained from an optimized model have accuracy comparable to the uncertainty in input data (e.g. rock mass properties, geology, etc.). This first paper defines the optimization framework, while a companion paper investigates its efficiency and application to practical mining and excavation‐related problems. Copyright © 2005 John Wiley & Sons, Ltd.
A continuum mechanics based framework for optimizing boundary and finite element meshes associated with underground excavations—accuracy, efficiency and applications
Authors: Zsáki Attila M. , Curran John H. 
Published: July 2005

AbstractA framework was developed to address the automatic optimization of the level of geometric detail required for stress analysis of underground excavations in mining, which was presented in the companion paper. The motivation for optimizing the mesh geometry stems from the over‐discretization of computational domain as the digital mine model is built while our knowledge of some of the input parameters is quite limited. Thus, the accuracy of the solution is not expected to be increased with a finely discretized mesh, only the computation time does. Therefore, it is acceptable if the results obtained from an optimized model have accuracy comparable to the uncertainty in input data (e.g. rock mass properties, geology, etc.). Although the mesh optimization framework automates the geometry optimization and reduces computation time, the accuracy of the solution from the resulting geometry must be evaluated to ensure the quality of the solution at the ‘region of interest’. Both a priori (mesh quality) and a posteriori (solution quality) measures are employed along with recording the mesh optimization time. Finally, the applicability of the mesh optimization framework is demonstrated by analysing a number of mining and civil engineering underground models. Copyright © 2005 John Wiley & Sons, Ltd.