bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for the HCl+(A) Formation in the Reaction of Ne(3P) with the Size-Selected HCl Dimer Using an Electrostatic Hexapole Field
Authors: Imura Kohei , Ohoyama Hiroshi , Kasai Toshio 
Published: April 2003

Abstract
Penning ionization of Ne(3P) metastable atom with size-selected HCl dimer was studied by using an electrostatic hexapole field and chemiluminescence detection. We found that the HCl dimer can also produce HCl+(A) ions in the reaction with Ne(3P) just like its corresponding monomer reaction. The internal energy distribution of HCl+(A) in the dimer reaction is cooler than that in the monomer reaction, reflecting the third-body effect due to the other HCl in the dimer.
Photo-Controllable and Fixative Optical Properties of Non-polymeric Liquid Crystals with Azobenzene Chromophore
Authors: Moriyama Masaya , Tamaoki Nobuyuki 
Published: April 2003

Abstract
A new series of non-polymer photochromic liquid crystalline compounds which form glassy solids maintaining the liquid crystalline molecular alignment has been synthesized; their optical properties such as cholesteric reflections, controlled by the intramolecular photoreaction and temperature, can be utilized for the construction of information-storing materials.
Crystal Structure Consisting Both of Segregated and Mixed Donor–Acceptor Columns
Authors: Otsuki Joe , Matsui Hiroyuki , Imamura Koichiro , Yoshikawa Isao , Araki Koji , Seno Manabu 
Published: April 2003

Abstract
A host molecule in which two acridine arms are held by an anthraquinone spacer cocrystallizes with TCNQ into a new type of organic donor–acceptor structure consisting both of segregated acceptor (anthraquinone) columns and mixed donor–acceptor columns (acridine–TCNQ) extending in different directions.
Supramolecular Liquid Crystals with Hydrogen-Bonding Self-Assembled T-Shaped Mesogens
Authors: Chen Dongzhong , Wan Lei , Fang Jianglin , Yu Xuehai 
Published: April 2003

Abstract
A new class of supramolecular liquid crystals with T-shaped mesogens are obtained by doubly hydrogen-bonded self-assembly of 2,6-bis(4-hexyloxybenzoylamino)pyridine and benzoic acid derivatives.
1H NMR Study of Hydroxy Groups in Mesoporous Molecular Sieve SBA-15
Authors: Shi Lei , Zou Yan , He Heyong 
Published: April 2003

Abstract
Three types of hydroxy groups, which are attributed to single, hydrogen-bonded and geminal SiOHs in mesoporous molecular sieve SBA-15 are directly and quantitatively observed by 1H ultrafast MAS NMR spectroscopy.
Probing the Nature of Cholera Toxin B Oligomer by the Atomic Force Microscopy
Authors: Wang Rong , Vengasandra Srikanth , Yan Funing 
Published: April 2003

Abstract
The nature of cholera toxin B oligomer was examined via the atomic force microscopy on the nanometer scale at the fluid tapping mode. The specific binding force between the B oligomer and the ganglioside GM1 receptor was quantified.
Novel Photocycloaddition of Aromatic Ketones to Cyclic Oligosilanes
Authors: Kako Masahiro , Gu Mei , Takenaka Yohei , Takagi Kentaro , Kondo Kazuhiro , Nakadaira Yasuhiro , Wakasa Masanobu , Hayashi Hisaharu 
Published: April 2003

Abstract
Photolysis of aromatic ketones (2,2,2-trifluoroacetophenone, acetophenone, and benzophenone) in the presence of cyclic oligosilanes afforded two types of cycloadducts depending on the nature of the ketone employed. The quenching of the excited triplet state of benzophenone by oligosilanes was investigated by laser flash photolysis.
Preparation of Organoytterbium Reagent from Ytterbium Trichloride and Organomagnesium
Authors: Matsubara Seijiro , Ikeda Takanori , Oshima Koichiro , Utimoto Kiitiro 
Published: April 2003

Abstract
The preparation of organolanthanoid species from diorganomagnesium and lanthanoid salt is discussed. Treatment of cerium trichloride or ytterbium trichloride with diorganomagnesium gave the corresponding organolanthanoid species much more efficiently than treatment of the salt with organomagnesium halide.
Orientation of Rotational Isomers of 1,2-Bis(2-anthryl)ethene in Liquid Crystals
Authors: Karatsu Takashi , Tanaka Yuuki , Imakawa Masanori , Fukui Keijiro , Kitamura Akihide 
Published: April 2003

Abstract
The fluorescence spectra of three rotational isomers of E-1,2-bis(2-anthryl)ethene (1) were obtained by the principal component analysis-self modeling (PCA-SM) method in solution. Based on the resolved spectra, the orientation of the rotational isomers in nematic and cholesteric liquid crystals (LC) were investigated. 1 mainly exists as the (s-trans, s-trans) conformer in these LC phases.
Formation Mechanism of Peroxides in Reactions of Cyclic Olefins with Ozone in Air
Authors: Hatakeyama Shiro , Sivanesan Subramanian , Urabe Taichiro 
Published: April 2003

Abstract
We carried out reactions of methyl-substituted cyclohexenes and α-pinene with ozone in air and elucidated the mechanisms of formation of the minor products (peroxides and formic acid). Peroxyacetic acid was formed only from the cyclohexenes with a methyl group on the double bond, whereas formic acid was produced in higher yields from the cyclohexenes without a methyl group on the double bond. These differences in product yields allowed us to elucidate the mechanism of formation of the products.
Enhanced Molecular-Shape Selectivity for Polyaromatic Hydrocarbons through Isotropic-to-Crystalline Phase Transition of Poly(octadecyl acrylate)
Authors: Ihara Hirotaka , Goto Yoshihiro , Sakurai Toshihiko , Takafuji Makoto , Sagawa Takashi , Nagaoka Shoji 
Published: April 2003

Abstract
We report temperature-triggered enhancement of molecular-shape selectivity by poly(octadecyl acrylate) which undergoes isotropic-to-crystalline phase transition. In this communication, it is also proposed that π–π interaction is included in this selective interaction and is enhanced through orientation of the carbonyl groups which are in a crystalline state.
Alignment Behavior of Discotic Nematic and Rectangular Columnar Phases on Self-Assembled Monolayers of Alkanethiol and Asymmetrical Disulfide
Authors: Monobe Hirosato , Azehara Hiroaki , Shimizu Yo , Fujihira Masamichi 
Published: April 2003

Abstract
Alignment behavior of a discotic liquid crystalline triphenylene (C8OBT) on substrates coated with self-assembled monolayers (SAMs) of alkanethiol and asymmetrical disulfide was investigated by polarized microscopy. Discotic nematic (ND) and rectangular columnar (Colr) phases of C8OBT shows a different alignment behavior depending on the element of SAMs. C8OBT exhibits a fan-shaped texture on an alkanethiol SAM in Colr phase, while it shows a planar alignment on a SAM of asymmetrical disulfide.
Thermal Stability of Alumina Modified Silica Fiber
Authors: Hasegawa Akira 
Published: April 2003

Abstract
Alumina modified silica fibers were prepared by covering with alumina fibrils. The modification induced the thermal stability under a stream of water at 1273 K without α-alumina formation. The morphology of alumina fibrils anchored on silica surface play an important role for the thermal stability in the presence of steam.
Electrochemical Behavior of Graphite–Lithium Intercalation Electrode in AlCl3–EMIC–LiCl–SOCl2 Room-Temperature Molten Salt
Authors: Koura Nobuyuki , Etoh Keiko , Idemoto Yasushi , Matsumoto Futoshi 
Published: April 2003

Abstract
The electrochemical behavior of a graphite (comprising only artificial graphite particles) electrode for intercalation and deintercalation of Li+, in AlCl3–1-ethyl-3-methylimidazolium chloride (EMIC)–LiCl–thionyl chloride (SOCl2) melt was studied.
Chiral Recognition by Multicenter Single Proton Hydrogen Bonding of Trifluorolactates
Authors: Katagiri Toshimasa , Uneyama Kenji 
Published: April 2003

Abstract
An X-ray crystallographic analysis of optically pure isopropyl trifluorolactate suggested possible seven centered hydrogen bondings with chirality. The hydroxy group was surrounded by three intra- and three intermolecular proton acceptors within reasonable hydrogen bonding distances.
A Facile Synthesis of 1,1-Disilylethenes via Me3MgLi-Induced Monomethylation of Dibromodisilylmethanes
Authors: Inoue Atsushi , Kondo Junichi , Shinokubo Hiroshi , Oshima Koichiro 
Published: April 2003

Abstract
Lithium trimethylmagnesate (Me3MgLi) induces monomethylation of dibromodisilylmethanes in excellent yields. Subsequent dehydrobromination of the resulting 1-bromo-1,1-disilylethanes with DBU affords 1,1-disilylethenes in good yields.
Sterically Protected Dipotassium Germanedithiolate
Authors: Matsumoto Tsuyoshi , Tatsumi Kazuyuki 
Published: April 2003

Abstract
The germanedithiols Dmp(Ar)Ge(SH)2 [Dmp=2,6-dimesitylphenyl; Ar = Dep (2,6-diethylphenyl) 1a, Tip (2,4,6-triisopropylphenyl) 1b] were synthesized by the reduction of hexathiagermepanes Dmp(Ar)GeS6 and tetrathiagermolanes Dmp(Ar)GeS4 with NaBH4. The treatment of 1awith 2 equiv of potassium hydride afforded the dipotassium germanedithiolate 2.
A Silicon–Silicon Triple Bond Surrounded by Bulky Terphenyl Groups
Authors: Takagi Nozomi , Nagase Shigeru 
Published: April 2003

Abstract
In search of a stable disilyne, effects of bulky 2,6-bis(2,4,6-triisopropylphenyl)phenyl (Ar*) groups on silicon–silicon triple bonding are investigated using density functional theory. It is predicted that Ar*Si≡SiAr* is very stable to isomerization and dimerization.
Highly Diastereoselective Aziridination of α,β-Unsaturated Amides Using Diaziridine
Authors: Ishihara Hiroyuki , Ito Yoshio N , Katsuki Tsutomu 
Published: April 2003

Abstract
Racemic 3-cyclohexyl-1-methyldiaziridine was found to react with α,β-unsaturated amides in basic conditions, giving N-unprotected trans-aziridines, while 3,3-pentamethylenediaziridine had been reported to afford cis-aziridines in high diastereoselectivity. The trans-selectivity was partially dependent on the stereochemistry of the substrate. The stereochemistries of these reactions were reasonably explained by the conformational analysis of the intermediary enolates.
In‐Situ Processing of Al Alloy Composites
Authors: Zheng Q. , Wu B. , Reddy R.G. 
Published: March 2003

AbstractIn‐situ processing of discontinuously reinforced Al alloy composites (DRACs) by gas‐bubbling method was investigated in this paper. Fine SiC and AlN particles were synthesized by bubbling C‐bearing and N‐bearing gases respectively. These results show that processing of DRACs through in‐situ gas‐bubbling route is technically feasible. Compared with conventional processing techniques, this method has the potential to produce DRACs with better microstructure and properties while with lower cost.
Preparation and Organization of Nanoscale Polyelectrolyte‐Coated Gold Nanoparticles
Authors: Mayya K.S. , Schoeler B. , Caruso F. 
Published: March 2003

AbstractThe layer‐by‐layer (LbL) desposition of oppositely charged polyelectrolytes from adsorption solutions of different ionic strength onto ∼7 nm diameter carboxylic acid‐derivatized gold nanoparticles has been studied. The polyelectrolyte‐modified nanoparticles were characterized by UV‐vis spectrophotometry, microelectrophoresis, analytical ultracentrifugation, and transmission electron microscopy. UV‐vis data showed that the peak plasmon absorption wavelength of the gold nanoparticles red‐shifted after each adsorption step, and microelectrophoresis experiments revealed a reversal in the surface charge of the nanoparticles following deposition of each layer. These data are consistent with the formation of polyelectrolyte layers on the nanoparticles. Analytical ultracentrifugation showed an increase in mean nanoparticle diameter on adsorption of the polyelectrolytes, confirming the formation of gold‐core/polyelectrolyte‐shell nanoparticles. Transmission electron microscopy studies showed no signs of aggregation of the polyelectrolyte‐coated nanoparticles. The adsorption of the polyelectrolyte‐coated gold nanoparticles onto oppositely charged planar supports has also been examined. UV‐vis spectrophotometry and atomic force microscopy showed increased amounts of nanoparticles were adsorbed with increasing ionic strength of the nanoparticle dispersions. This allows control of the nanoparticle surface loading by varying the salt content in the nanoparticle dispersions used for adsorption. The LbL strategy used in this work is expected to be applicable to other nanoparticles (e.g., semiconductors, phosphors), thus providing a facile means for their controlled surface modification through polyelectrolyte nanolayering. Such nanoparticles are envisaged to have applications in the biomedical and bioanalytical fields, and to be useful building blocks for the creation of advanced nanoparticle‐based films.
Chemical and Structural Investigations of Biomimetically Grown Fluorapatite–Gelatin Composite Aggregates
Authors: Busch S. , Schwarz U. , Kniep R. 
Published: March 2003

AbstractDeeper understanding of the basic principles of biomineralization is a major challenge for present and future research. The high complexity of in‐vivo conditions calls for simplified model systems that still involve dynamic processes like reorganization, formation, self‐organization, and development of patterns, respectively. The present contribution deals with hierarchically ordered spherical aggregates of fluorapatite–gelatin composites with fractal architecture that are grown in gelatin matrices. The model system was chosen to mimic formation conditions on a lower level of complexity compared with the natural formation of calcified tissue (bone, teeth). In order to gain insight into structure formation and the motif for this special kind of morphogenesis we investigated the interaction of the organic and inorganic components of aggregates in different growth stages by detailed chemical analyses, thermoanalytical measurements, X‐ray diffraction on solitary particles, and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) investigations. The close relation of the results and observations to calcified tissue may stimulate advanced interests in the fields of medical and materials development.
Low‐k Insulators as the Choice of Dielectrics in Organic Field‐Effect Transistors
Authors: Veres J. , Ogier S.D. , Leeming S.W. , Cupertino D.C. , Mohialdin Khaffaf S. 
Published: March 2003

AbstractIn this paper, we present a new effect influencing the operation of organic field‐effect transistors resulting from the choice of gate insulator material. In a series of studies it was found that the interaction between the insulator and the semiconductor materials plays an important role in carrier transport. The insulator is not only capable of affecting the morphology of the semiconductor layer, but can also change the density of states by local polarization effects. Carrier localization is enhanced by insulators with large permittivities, due to the random dipole field present at the interface. We have investigated this effect on a number of disordered organic semiconductor materials, and show here that significant benefits are achievable by the use of low‐k dielectrics as opposed to the existing trend of increasing the permittivity for low operational voltage. We also discuss fundamental differences in the case of field‐effect transistors with band‐like semiconductors.
Near‐Infrared Light‐Emitting Diodes (LEDs) Based on Poly(phenylene)/Yb‐tris(β‐Diketonate) Complexes
Authors: Kang T.‐S. , Harrison B.S. , Bouguettaya M. , Foley T.J. , Boncella J.M. , Schanze K.S. , Reynolds J.R. 
Published: March 2003

AbstractNear‐infrared‐emitting electroluminescent (EL) devices using blue‐light‐emitting polymers blended with the Yb complexes Yb(DBM)3phen (DBM = dibenzoylmethane), Yb(DNM)3phen (DNM = dinaphthoylmethane), and Yb(TPP)L(OEt) (L(OEt) = [(C5H5)Co{P(O)Et2}3]–) have been studied. EL devices composed of Yb(DNM)3phen blended with PPP‐OR11 showed enhanced near‐IR output at 977 nm when compared to those fabricated with Yb(DBM)3phen/PPP‐OR11 blends. The maximum near‐IR external efficiencies of the devices with Yb(DBM)3phen and Yb(DNM)3phen are, respectively, 7 × 10–5 (at 6 V and at 0.81 mA mm–2) and 4 × 10–4 (at 7 V, and 0.74 mA mm–2). The optimal blend composition for EL device performance consisted of PPP‐OR11 blended with 10–20 mol‐% Yb(DNM)3phen. A device fabricated using Yb‐(TPP)L(OEt)/PPP‐OR11 showed significantly enhanced near‐IR output efficiency, and future efforts will focus on devices fabricated using porphyrin‐based materials.
The Effect of Core Delocalization on Intermolecular Interactions in Conjugated Dendrimers
Authors: Beavington R. , Frampton M.J. , Lupton J.M. , Burn P.L. , Samuel I.D.W. 
Published: March 2003

AbstractFour generations of conjugated dendrimers that contain 1,3,5‐tris(distyrylbenzenyl)benzene cores, stilbene dendrons, and t‐butyl surface groups have been synthesized. The dendrimers were synthesized by coupling benzylphosphonate‐focused dendrons with 1,3,5‐tris(4‐formylstilbenyl)benzene to give the dendrimers in yields in the range 60–82 %. We have probed the optoelectronic properties of the dendrimers by electrochemistry, photoluminescence, and in light‐emitting device structures. We have found that the degree of aggregation is strongly generation dependent. We compared the properties of these benzene‐centered dendrimers with an equivalent family of dendrimers that differs only in having a nitrogen atom as the central unit. We found that the aggregation of dendrimers was strongly dependent on the degree of delocalization across the central unit. The dendrimers with the benzene central unit, which have three localized distyrylbenzene chromophores, were found to aggregate more strongly in the solid state than those with nitrogen as the central unit. In the latter case the electroactive component is comprised of all three distyrylbenzene units and the nitrogen atom.
Self‐Assembled Monolayer Coatings on Nanostencils for the Reduction of Materials Adhesion
Authors: Kölbel M. , Tjerkstra R.W. , Kim G. , Brugger J. , van Rijn C.J.M. , Nijdam W. , Huskens J. , Reinhoudt D.N. 
Published: March 2003

AbstractNanostencils (shadow masks with submicrometer apertures in a thin silicon nitride membrane) are promising tools for the facile one‐step generation of nanopatterns of various materials by physical vapor deposition. Evaporation through a shadow mask is accompanied by gradual clogging of the apertures due to adhesion of evaporated material. In order to reduce this effect, nanostencils were coated with alkyl and perfluoroalkyl self‐assembled monolayers (SAMs). The formation and properties of SAMs on planar silicon nitride substrates were studied by contact angle goniometry, X‐ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The SAMs are stable under evaporation of gold at various angles. SAM‐coated nanostencils showed considerably less adhesion of gold compared to bare SixNy stencils.
Engineered Sensitivity of Structured Tin Dioxide Chemical Sensors: Opaline Architectures with Controlled Necking
Authors: Scott R.W.J. , Yang S.M. , Coombs N. , Ozin G.A. , Williams D.E. 
Published: March 2003

AbstractStructure–property relationships in tin dioxide materials have been studied utilizing a reverse templating strategy to synthesize opaline structures with controlled neck dimensions between spheres. The necking dimensions could be controlled by sintering the parent silica opals at temperatures between 700 and 1050 °C. Inverted polymer opals were synthesized by infiltrating the silica opals with styrene, followed by thermally induced polymerization, and removal of the silica with HF. Tin dioxide opals with controlled microstructures were then synthesized from these inverted polymer opals. The gas sensing response of these materials to carbon monoxide could be understood as a function of the necking diameter in the resulting tin dioxide opals.
Mono‐Bisthienylethene Ring‐Fused versus Multi‐Bisthienylethene Ring‐Fused Photochromic Hybrids
Authors: Luo Q. , Chen B. , Wang M. , Tian H. 
Published: March 2003

AbstractNovel bisthienylethene‐based tetraazaporphyrin and phthalocyanine hybrids (BTE–TAPs) were prepared as photo‐switching molecules. All new compounds were characterized by mass spectrometry (MS), 1H NMR spectroscopy, elemental analysis, UV‐vis absorption, and luminescence spectroscopy. All BTE–TAP compounds undergo open‐to‐closed and closed‐to‐open ring photoisomerizations in different quantum yields by irradiation with 365 nm or 730 nm light. The near‐IR luminescence of the hybrids can be regulated in a reversible manner by the photoisomerization of the bisthienylethene moiety. These compounds are useful as fluorescent probes and as non‐destructive readouts for erasable memory media. The phosphorescent BTE–TAP–PtII complex was also prepared, and its photochromism and changes in phosphorescence in a polycarbonate film were studied. These properties could give rise to other practical uses of BTE–TAP hybrids.
Composites of Perylene Chromophores and Layered Double Hydroxides: Direct Synthesis, Characterization, and Photo‐ and Chemical Stability
Authors: Bauer J. , Behrens P. , Speckbacher M. , Langhals H. 
Published: March 2003

AbstractComposites of the tetra‐anion of the perylene dye N,N′‐di(phenyl‐3,5‐disulfonic acid)perylene‐3,4:9,10‐tetracarboxydiimide (PBITS) with layered double hydroxides (LDHs) were formed by direct synthesis (co‐precipitation at constant pH). The LDHs were of the hydrotalcite (Mg–Al–OH and Zn–Al–OH compositions). During synthesis of the hydrocalumite type (Ca–Al–OH), partial destruction of the dye occurs, being more pronounced at higher pH values. The composites were characterized with regard to their composition by elemental and thermal analysis. From UV‐vis spectroscopic data and powder X‐ray diffraction, a structural model is developed for the composites. In the galleries between the hydroxide layers, the chromophore molecules are stacked in an J‐type arrangement. The compounds have brilliant colors and are insoluble in common solvents. With regard to a possible application as pigments, their photostability and their chemical resistance against a typical application environment was tested. The photostability of the dye molecules and their chemical resistance against setting cement are slightly raised by the occlusion within the LDH structure; however, the photostability of the LDH–cement is lower than that of cement colored with the pure perylene dye.
Sodium Perborate—A Convenient Baeyer–Villiger Oxidation Reagent in the Synthesis of the Corey Aldehyde
Authors: Espiritu Maria , Handley Paul N. , Neumann Ralf 
Published: March 2003

AbstractSodium perborate tetrahydrate is a cheap, safe and readily available alternative to the commonly used peracetic acid for the Baeyer–Villiger oxidation step of the Corey aldehyde synthesis. Chloroketo acid 1 is smoothly converted by sodium perborate tetrahydrate in formic acid to the chloroketolactone 2 in 66% isolated yield. In contrast to previously reported reactions using other oxidants, the formation of the lactone is completely regioselective in favour of the “bridgehead‐migrated” isomer 2.
Microwave Heating Effects Rapid and Selective Decarboalkoxylation of Mono‐Alkylated Malonates and β‐Ketoesters
Authors: Curran Dennis P. , Zhang Qisheng 
Published: March 2003

AbstractBrief microwave irradiation of mono‐alkylated malonates and β‐ketoesters at 160–200 °C in wet DMF induces smooth and selective decarboalkoxylation. Observations suggest that this reaction occurs by nucleophilic attack of water at the ester carbonyl carbon (hydrolysis) followed by decarboxylation of the resulting acid. The process occurs despite the absence of traditional acid, base or nucleophile catalysts or reagents.