bluuebunny/crossref_metadata_2025_split huggingface dataset:
Racemic-to-Chiral Transformation in Cobaloxime Complex Crystals Only by Photoirradiation
Authors: Nemoto Takashi , Ohashi Yuji 
Published: December 2004

Abstract
The cobaloxime complex crystal with the racemic-1-cyanoethyl group and piperidine as axial ligands, which has a chiral space group of P212121, changed its cell dimensions with retention of the single crystal form on exposure to visible light. The chloroform solution of the crystals after irradiation showed the optical rotation ([α]D = 30°). This indicates the racemic-to-chiral transformation occurred in the crystal only by photoirradiation. The crystal before irradiation, analyzed by X-rays, has two complexes with R- and S-1-cyanoethyl groups in the asymmetric unit. After irradiation, one of the complexes with the S group, which has a larger reaction cavity than the R group, was partly inverted to create a disordered structure. The R : S ratio in the crystal changed from 50 : 50 to 70 : 30. The final ratio of 70 : 30 is well explained by the symmetric shape of the reaction cavity after the change. For the cobaloxime complex crystal with the racemic-1-cyanoethyl group and pyrrolidine as axial ligands, a similar transformation was observed. The racemic crystal with the space group P1 has four complexes in a unit cell, two of which have a R-1-cyanoethyl group while the other two complexes have a S-1-cyanoethyl group. The complexes with the S group, which have larger cavities than those with the R group, were partly inverted to create the opposite configuration. This caused optical enrichment in the crystal. Such a racemic-to-chiral transformation will be observed not rarely but commonly if the racemic crystals with chiral space groups will be examined cautiously.
Mechanism of the Photosensitized Chemiluminescence of Luminol
Authors: Yasuta Norihiko , Takahashi Sinjiro , Takenaka Nobuo , Takemura Takeshi 
Published: December 2004

Abstract
The photosensitized chemiluminescence (CL) of luminol in basic aqueous solution has been investigated by pulsed laser irradiation and by steady state light irradiation in order to clarify the CL in terms of Type-I (electron transfer) and Type-II (singlet oxygen) mechanisms. Short-lived (μs) and long-lived (ms) CL were observed at 420 nm upon pulsed laser irradiation near 530 nm of the luminol/sensitizer reaction mixture. The kinetics of the CL decay is explained by four rate constants,
I(t) = Aex{exp(−k2t) − exp(−k1t)} + Bex{exp(−k4t) − exp(−k3t)}.
These results, in addition to the results under steady state conditions, suggest that the long-lived CL dominates the photosensitized CL, which is caused by electron transfer to the triplet state of the sensitizers from luminol (Type-I). On the other hand, short-lived CL is due to a reaction between singlet oxygen and luminol (Type-II), the efficiency of which is smaller by two orders of magnitude compared to that of the Type-I mechanism.
A Possibility of Macroscopically Asymmetric Diffusion on Stepped Surfaces
Authors: Seto Takatoshi 
Published: December 2004

Abstract
We studied the macroscopic-scale surface diffusion of adsorbates under strong adsorbate–adsorbate lateral interactions (A–A potential) on a surface with periodically repeated asymmetric potential curves, such as a well-ordered stepped surface. By considering a potential curve made of adsorbate–substrate (A–S) and A–A potentials in a random-walk model, we found an asymmetry in a migration probability of an adsorbate in opposite directions. On this basis, we derived and predicted the existence of macroscopically asymmetric diffusion. A Monte-Carlo calculation of the random walk of adsorbates with a certain strong repulsive A–A potential on fcc (112) or bcc (013) caused the adsorbates to diffuse more in a direction of jumping the minimum A–S activation energy, and a difference in flux of the adsorbates in opposite directions greatly depended on the concentration.
Radiolytic and Thermal Dehalogenation of CFC-113 Adsorbed on Molecular Sieve 13X
Authors: Yamamoto Yukio , Tagawa Seiichi 
Published: December 2004

Abstract
The reductive dehalogenation of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) has been radiolytically and thermally initiated on molecular sieve 13X. The molecular sieve adsorbing CFC-113 was irradiated with γ-rays or heated, and was then soaked in water. The Cl− and F− concentrations and the pH of the supernatant solutions were measured to follow the dehalogenation reaction. These values for samples irradiated at a dose rate of 7.8 kGy h−1 and heated at 150 °C were almost the same when the irradiation time was twenty-times longer than the heating time. The F− concentration once increased and then decreased with the reaction time, whereas the Cl− concentration increased continuously. The F−, once produced, may be consumed with the denatured molecular sieve. When the molecular sieve adsorbing 2-propanol together with CFC-113 was irradiated, the dechlorination proceeded by a chain reaction, but the defluorination was inhibited. On the other hand, when heated in the presence of 2-propanol, both the dechlorination and the defluorination were largely suppressed. The pH of the supernatant solutions decreased from an alkaline value to a neutral or acidic one along with dehalogenation. Radiolysis of CFC-113 on activated charcoal was also examined, but the dehalogenation rates were much slower than those on the molecular sieve.
Photoemission Cross Sections for Fragments and Molecular Ions Produced by Collisions of He(2 3S) Atoms with SiCl4 and GeCl4
Authors: Tokue Ikuo , Tanaka Hiroyuki , Yamasaki Katsuyoshi 
Published: December 2004

Abstract
Photoemissions from excited fragments and molecular ions produced by collisions of He(2 3S) with SiCl4 and GeCl4 have been studied at the relative collision energy of 120—210 meV. Total emission cross sections in the 200—760 nm range for SiCl4 and GeCl4 are evaluated to be 4.5 ± 0.8 and 2.2 ± 0.4, respectively, in 10−20 m2 units. Emission cross sections for SiCl4+(), GeCl4+(), and Ge I atomic lines slightly decrease with increases in the collision energy. This originates from the fact that the effective potentials of He(2 3S) with SiCl4 and GeCl4 are slightly attractive. The branching ratio of Ge I states observed from GeCl4 is consistent with a simple dissociation model assuming equipartition of the available energy. These results are compatible with the harpoon mechanism as an initial step for formation of Ge I from GeCl4. The emission cross section for the SiCl(B′–X) band increases with the collision energy. This indicates that the effective potential between He(2 3S) and SiCl4 is repulsive, and that the SiCl(B′) state seems to be produced directly from SiCl4 by an excitation transfer mechanism via superexcited states.
Organotin Esters of N-Phthaloylamino Acids: Synthesis, Spectroscopic Characterization, and Biological Activities
Authors: Ashfaq Muhammad , Majeed Abdul , Rauf Abdul , Khanzada Abdul Wahab Khan , Shah Wali Ullah , Ansari Muhammad Iqbal 
Published: December 2004

Abstract
The synthesis, physical nature and spectroscopic characterization, i.e. CHN analyses as well as the IR, 1H-, 13C-, 119Sn NMR and 119mSn Mössbauer spectrometries, of a series of new organotin complexes of N-phthaloylamino acids are described. The monomeric diorganotin complexes possess a trans octahedral geometry. The dimeric tetraorganotin complexes have a penta-coordinate environment. The triphenyltin with N-phthaloylamino acids are assigned a polymeric trigonal bipyramidal geometry in the solid form and a tetrahedral structure in an inert solvent, while tricyclohexyltin with N-phthaloylamino acids complexes possess a tetrahedral geometry. ED50 and biological activities tests were also carried out, which indicated powerful biocidal effects.
Structure and Organic Gas-Adsorption Properties of Some Polyamine Intercalated α-Zirconium Phosphates
Authors: Danjo Mayumi , Hayashi Aki , Nakayama Hirokazu , Kimira Yumi , Shimizu Tomoko , Mizuguchi Yukari , Yagita Yukari , Tsuhako Mitsutomo , Nariai Hiroyuki , Motooka Itaru 
Published: December 2004

Abstract
The intercalation of polyamine into α-zirconium phosphate (α-ZrP) was examined at room temperature and 80 °C. In triethylenetetramine (3E4A), tetraethylenepentamine (4E5A), and pentaethylenehexamine (5E6A) the temperature of the reactions influenced the rate of intercalation, but did not effect the structure of the intercalation compound. On the other hand, the ratios of the constituent phases in the N,N′-bis(3-aminopropyl)-1,3-propanediamine (3P4A) intercalated solid were greatly influenced by the reaction temperature, and two phases with the different interlayer distances could be formed by controlling it. In the phase with an interlayer distance of d = 20 Å, obtained predominantly at 80 °C, 3P4A was present as a monolayer of extended molecules in the interlayer region, in which the longitudinal axis of 3P4A was inclined at ca. 60° to the α-ZrP layers. In the phase with d = 17 Å, obtained at room temperature, 3P4A existed as a bent form. These polyamine intercalated solids drastically adsorbed acetic acid, formaldehyde, acetaldehyde, and cinnamaldehyde.
Potential Step Voltammetry of Ion-Transfer at Liquid/Liquid Interface with Preceding Chemical Reaction. Determination of the Rate and Equilibrium Constants from Voltammetric Curves
Authors: Katano Hajime , Senda Mitsugi 
Published: December 2004

Abstract
Theoretical equations of the potential step voltammograms for the ion-transfer with preceding chemical reaction have been derived. Results were applied to analyze the voltammetric behavior of 1,4,7,10,13,16-hexathiacyclooctadecane-assisted transfer of Pb2+ ion across the nitrobenzene/water interface from aqueous medium containing citrate3− ion. The dissociation and association rate constants and the equilibrium constant of Pb2+–citrate3− complex in aqueous medium are determined to be 1.2 × 104 s−1 and 1.2 × 1010 M−1 s−1 and 106.0 M−1, respectively. The results are compared with those obtained by potential sweep voltammetry.
Coligand Effects on Bonding Mode. Synthesis and Properties of (Diallylmalonato)platinum(II) Complexes of P vs. N Donating Ligand
Authors: Jung Ok-Sang , Lee Young-A , Park Sung Ho , Yoo Kyung Ho 
Published: December 2004

Abstract
The reaction of cis-[PtII(OH)2A2] (A = triethylphosphine (PEt3); A2 = tetrahydro-4H-pyran-4,4-dimethanamine (hpda)) with diallylmalonic acid in aqueous solution affords cis-[Pt(dam)A2] (dam = diallylmalonate). The bonding mode of the dam is dependent upon the donation effect of the phosphine vs the nitrogen coligand. The crystal structure of cis-[Pt(dam)(PEt3)2] (C21H40O4P2Pt·H2O: monoclinic P21/c, a = 13.918(2), b = 12.464(1), c = 15.737(1) Å, β = 107.097(8)°, V = 2609.4(4) Å3, Z = 4, R = 0.033) discloses that the dam is bonded to the platinum atom in a (κ2O3)-mode (Pt–O = 2.057(4), 2.061(4) Å) with two phosphine ligands in the cis position. In contrast, for cis-[Pt(dam)(hpda)] (C16H16N2O5Pt·4.5H2O: monoclinic C2/c, a = 28.250(3), b = 11.169(1), c = 13.368(4) Å, β = 94.16(1)°, V = 4207(1) Å3, Z = 8, R = 0.0293), the dam ligand is chelated to the platinum(II) ion in a (κO,η2-C,C)-mode (Pt–O = 2.004(4) Å; Pt–C = 2.089(6), 2.101(6) Å) in the solid state. cis-[Pt(κ2O3-dam)(PEt3)2] easily reacts with KBr pellet matrix for IR measurements while cis-[Pt(κO,η2-C,C-dam)(hpda)] is inert in the pellet. In solution, however, the structure of cis-[Pt(κ2O3-dam)(PEt3)2] is locked, whereas cis-[Pt(κO,η2-C,C-dam)(hpda)] can be isomerized to cis-[Pt(κ2O3-dam)(hpda)].
An Attempted Synthesis of [7][7]Circulene: Synthesis and Characterization of Triple-Layered [2.2]Phenanthreno[2.2]naphthalenophenanthrenophane
Authors: Yano Koji , Matsuda Susumu , Tani Keita , Yamamoto Koji , Matsubara Hiroshi 
Published: December 2004

Abstract
The synthesis of the title compound, a triple-layered cyclophane, is described. The unusually strained structure was supported by its 1H NMR spectra, electronic spectra, and X-ray crystallographic analysis.
Structural Evidence for an Independent Inclusion of Hexyl and Octyl Chains of Hexyldimethyloctylammonium Bromide in an α-Cyclodextrin Cavity
Authors: Funasaki Noriaki , Yamauchi Koji , Ishikawa Seiji , Hirota Shun 
Published: December 2004

Abstract
Proton NMR spectroscopy was applied to determine the macroscopic binding constants and the solution structures of the 1:1 and 1:2 complexes between N,N,N-hexyldimethyloctylammonium bromide (HDOAB) and α-cyclodextrin (α-CD). The terminal methyls of the hexyl and octyl groups of HDOAB are distinguishable from each other in the NMR spectrum. The chemical-shift variations of these methyls, compared with the α-CD complexes of hexyltrimethylammonium (HTAB) and octyltrimetylammonium (OTAB) bromides, indicated that this system formed two 1:1 complexes (10% hexyl-in complex and 90% octyl-in complex). The chemical-shift variations of HDOAB and α-CD protons with the 1:1 and 1:2 complexations were quantitatively explained based on the assumption that the geometry of the hexyl and octyl groups of the HDOAB complexes with α-CD is identical to that of the HTAB and OTAB. This finding indicated that the hexyl and octyl groups bind to α-CD independently. Based on the assumption that the microscopic binding constants of the hexyl and octyl groups of HDOAB are identical to the macroscopic 1:1 binding constants of HTAB and OTAB with α-CD, the mole fraction of the hexyl-in complex in the 1:1 complex was estimated to be 0.11. This is very close to the above-mentioned estimation from the chemical-shift variations of the terminal methyls. The intensities of intermolecular cross-peaks on the ROESY spectrum of a 3 mM HDOAB and 3 mM α-CD solution indicated that the octyl-in complex is the predominant 1:1 complex. The present method and result will serve to estimate noncovalent interactions, binding equilibria, and solution structures of other multiple supramolecular complexes.
A Structural Phase Transition and Molecular Motions in (C2H5NH3)2[ZnBr4] Studied by 1H NMR and X-ray Diffraction
Authors: Horiuchi Keizo , Iijima Chieko , Miyagi Shinji , Yogi Hayato , Fukami Takanori , Ikeda Ryuichi 
Published: December 2004

Abstract
The 1H NMR spin–lattice relaxation times and the second moments of the resonance linewidth were measured as a function of temperature in (C2H5NH3)2[ZnBr4]. The crystal structure at 295 K was determined to be orthorhombic with space group of P212121 by the single-crystal X-ray diffraction method. The crystal undergoes a 1st order structural phase transition at Tc = 300 K, which is driven by the disordering of cationic orientations. The crystal structure above Tc is inferred to be orthorhombic with space group of Pmnb().
An Effective System to Synthesize Hypolipidemic Active α-Asarone and Related Methoxylated (E)-Arylalkenes
Authors: Sharma Anuj , Joshi Bhupendra P , Sinha Arun K 
Published: December 2004

Abstract
Methoxylated (E)-arylalkenes (1a–1k) were prepared in two steps by an improved Grignard reaction comprising the reverse addition of alkylmagnesium bromide to benzaldehydes (2a–2k) in anhydrous ether and toluene into arylalkanols (3a–3k) in high yield, followed by dehydration with silica gel under microwave irradiation for 3–12 min, depending upon the substituents attached to the aromatic ring to afford hypolipidemic active α-asarone (1a) and related methoxylated (E)-arylalkenes (1b–1k).
Asymmetric Transformation of Enones with Synechococcus sp. PCC 7942
Authors: Shimoda Kei , Kubota Naoji , Hamada Hiroki , Yamane Shin-ya , Hirata Toshifumi 
Published: December 2004

Abstract
Asymmetric transformation of enones was investigated with cultured cells of Synechococcus sp. PCC 7942 (a cyanobacterium). The cells reduced both the endocyclic C–C double bond of s-trans enones and the exocyclic C–C double bond of s-cis enones with high enantioselectivity to afford optically active α-substituted (S)-ketones under illumination. In addition, the reduction of the double bond of these enones was accompanied by the formation of saturated alcohols. The cells preferentially reduced simple aliphatic ketones rather than cyclic ones to the corresponding (S)-alcohols with excellent enantioselectivity.
A Novel Method for Preparing PEMFC Catalytic Layers
Authors: Zhang Jianlu , Wang Xiaoli , Hu Jingwei , Yi Baolian , Zhang Huamin 
Published: December 2004

Abstract
A novel PEMFC catalytic layer was fabricated by a Nafion-pyrolyzed method, which demonstrated a high performance with a maximum power density of 0.82 W/cm2 on an electrode prepared by this method. The effects of the heat-treatment temperature and Nafion content in the catalyst layer on performance were studied.
Non-Invasive ESR Measurements for in vivo Kinetic Studies of a Nitroxide Radical in the Liver of a Rat by a Surface-Coil-Type Resonator under a Field Gradient
Authors: Yokoyama Hidekatsu , Tada Mika , Sato Toshiyuki , Ohya Hiroaki , Kamada Hitoshi 
Published: December 2004

Abstract
A non-invasive ESR measuring method for in vivo kinetic studies of a nitroxide radical in the liver of a rat by combining a surface-coil-type resonator (SCR) and field gradient method was developed. The depth across which a microwave magnetic field (B1) can penetrate under the SCR was about 4 mm. Using the SCR, ESR measurements without any invasive surgical procedures were made on the upper abdomen of a rat that received an intravenous injection of a nitroxide radical under a field gradient along the B1-direction. It was found that the decay rate of nitroxide radical 4 mm under the skin (i.e., in the liver) is fast compared to that near the skin.
Regioselective Preparation of 1,6- and 1,8-Dihydroxy-9,10-anthraquinones from the Common Intermediates: Synthesis of Aloesaponarin I and K1115A
Authors: Uno Hidemitsu , Nagamachi Yumi , Honda Erina , Masumoto Akane , Ono Noboru 
Published: December 2004

Abstract
Treatment of 3-acyl-2-[(2,2-dimethyl-6-oxo-1,3-dioxin-4-yl)methyl]-5-methoxy-1,4-naphthoquinones with K2CO3 in an alcohol brought about the intramolecular condensation to give 1-alkyl-3-hydroxy-8-methoxy-9,10-anthraquinone-2-carboxylates in good yields, while the same naphthoquinone gave 1-hydroxy-8-methoxy-9,10-anthraquinone-3-acetic acid in good yield by treatment with KHMDS.
The Mechanochemical Synthesis and Properties of the Fullerene Trimer C180
Authors: Komatsu Koichi , Fujiwara Koichi , Murata Yasujiro 
Published: December 2004

Abstract
A solid-state reaction of C60 with 4-aminopyridine as a catalyst under high-speed vibration milling conditions afforded fullerene trimer C180, which was characterized by IR and UV–vis spectroscopies as well as the APCI mass spectroscopy of the cyanated derivative.
Amperometric Detection of Polyphenols Using Peroxidase-Immobilized Gold Electrodes
Authors: Imabayashi Shin-ichiro , Kong Young-Tae , Watanabe Masayoshi 
Published: December 2004

Abstract
Horseradish peroxidase (HRP) is covalently immobilized on a self-assembled monolayer of mercaptopropionic acid on vapor-deposited gold electrode. The electrode allows the polyphenol detection down to 2 µmol dm−3 with a linear relationship up to 25 µmol dm−3. The reduction current of oxidized polyphenol intermediate formed during the enzymatic reaction in the presence of H2O2 is proportional to the concentration of polyphenol. The present method is applicable to the determination of the total polyphenol content in wine and tea.
Pd(II) Complexes Mediated Hydrolytic Cleavage of Insulin B Chain: Regioselectivity and Influence of Peptide Secondary Structure
Authors: Luo Xuemei , He Weijiang , Zhang Yu , Guo Zijian , Zhu Longgen 
Published: December 2004

Abstract
Electrospray mass spectrometry studies show that the binding of Pd(II) complexes and the site of cleavage are highly dependent on the secondary structure and local environment of oxidized insulin B chain (B). The hydrolytic cleavage of denatured B by Pd(II) complexes is monitored by HPLC, which follows first order kinetics with half-life of 4.8 days at 40 °C. Two amide bonds at Leu6-Cys7 and Gly8-Ser9 are selectively cleaved.
A New Series of Liquid Crystals Having a Terminal Carbonyl Group
Authors: Okamoto Hiroaki , Okamoto Tsuyoshi , Takenaka Shunsuke 
Published: December 2004

Abstract
Some homologs of 5-(4-alkoxyphenyl)-1,3-dioxan-2-one exhibit a monotropic smectic A phase commencing from the pentyloxy homolog.
Analyses of Amino Acids and Benzene Extracts in the Condensed Water Collected from Inside of the MIR Space Station
Authors: Mita Hajime , Nakano Tamotsu , Shimoyama Akira 
Published: December 2004

Abstract
Amino acids were found in the condensed water samples collected from the inside of MIR indicating the presence of microorganisms probably grown in orbit. Aromatic alcohols and aldehydes were found in the benzene extracts of the water samples and they were likely from the sterilants and fragrances used in MIR. Present analysis of the benzene extracts failed to find a signature of the fire on February 23, 1997 that took place inside MIR.
Gas-Phase Adiponitrile Hydrogenation over Modified Ni–P/SiO2 Amorphous Catalysts
Authors: Li Hexing , Wang Minghui , Xu Yeping 
Published: December 2004

Abstract
Gas-phase hydrogenation of adiponitrile were carried out in a fixed-bed reactor at 1 atm pressure, and in the absence of ammonia. In comparison with other Ni-based catalysts, the Ni–P/SiO2 amorphous catalyst exhibited higher activity and/or better selectivity to 1,6-hexanediamine, which could be further improved by W or MgO-additives.
Easy Preparation of Bioactive Peptides from the Novel Nα-Trifluoroethyl Amino Acids
Authors: DesMarteau Darryl D , Montanari Vittorio 
Published: December 2004

Abstract
N α-Trifluoroethyl amino acids have been prepared for the first time and unexpectedly found to behave as conventionally N-protected amino acids. Novel unnatural peptides are easily prepared in high yields without racemization. The observed chemistry results from steric factors as well as from the acidity of the CF3CH2NH group, according to comparative experiments. Of ten dipeptides that were tested for antitumor activity, CF3CH2–l-Tyr–l-Ile–OtBu was the most active.
Facile Routes to Ru(η3-Allyl)(NO)(PPh3)2 Complexes via Hydrometallation of RuH(NO)(PPh3)3 to 1,3-Butadienes and Allenes
Authors: Nakanishi Saburo , Sasabe Hisahiro , Takata Toshikazu 
Published: December 2004

Abstract
Hydrometallation of RuH(NO)(PPh3)3 to 1,3-butadienes and allenes proceeded regio- and stereoselectively to give η3-allyl ruthenium complexes as a sole complex in good yields. The structure of the complex was unambiguously determined by X-ray analysis.
Direct and Selective Syntheses of α,α-Dichloroethyl Ketones or Their Ethyl Trimethylsilyl Mixed Acetals by the Reactions of Methoxymethyl or Ethyl Carboxylates with 1,1-Dichloroethyllithium in the Presence of Chlorotrimethylsilane
Authors: Shiina Isamu , Imai Yumiko , Suzuki Masahiko , Yanagisawa Manabu , Mukaiyama Teruaki 
Published: December 2004

Abstract
1,1-Dichloroethyllithium (1), generated by treating 1,1-dichloroethane (2) with lithium diisopropylamide (LDA) or n-butyllithium, reacted with methoxymethyl carboxylates in the coexistence of chlorotrimethylsilane (3) to afford the corresponding α,α-dichloroethyl ketones in good yields. On the other hand, 1 reacted with ethyl carboxylates under the above reaction conditions to give 2,2-dichloro-1-alkyl-1-ethoxy-1-(trimethylsiloxy)propanes selectively in good yields.
Large Nanosecond and Picosecond Optical Limiting Response of Novel Transition-Metal Planar Chalcogen Cluster Complex [WS4Cu4I2(py)6]
Authors: Song Yinglin , Zhang Chi , Zhao Xiuli , Wang Yuxiao , Fang Guangyu , Jin Guocheng , Qu Shiliang , Wu Shupeng , Xin Xinquan , Ye Hongan 
Published: December 2004

Abstract
Large nanosecond and picosecond optical limiting responses of novel planar transition-metal chalcogen cluster complex [WS4Cu4I2(py)6] were studied by using a double frequency nanosecond/picosecond Nd:YAG pulse laser system at wavelength of 532 nm. The experimental results demonstrated that the optical limiting behaviors of this metal cluster are better than fullerene-C60 under both nanosecond and picosecond laser pulse excitation.