bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Synthesized Lacquer Films Using Pyrolysis-Gas Chromatography/Mass Spectrometry
Authors: Kamiya Yukio , Niimura Yasunori , Miyakoshi Tetsuo 
Published: September 2002

Abstract
The trienyl urushiols, which are major urushiol components, were synthesized via the Wittig reaction. The synthesized urushiols were then polymerized into synthesized lacquer films by laccase-catalyzed oxidation. The resulting lacquer films were characterized using Pyrolysis-GC/MS, and the results were compared with that of a natural lacquer film in order to evaluate their polymerization mechanism and molecular structure. Based on these results, it was found that natural lacquer films are terminated with the monoenyl and saturated urushiol, and that the polymerization of synthesized urushiol proceeds through the laccase-catalyzed nucleus-side chain C-O coupling and autoxidative side chain-side chain C-C coupling, like the natural lacquer film.
Synthesis and Characterization of Photoconducting Polyaniline-TiO2 Nanocomposite
Authors: Feng Wei , Sun Enhai , Fujii Akihiko , Wu Hongcai , Niihara Koichi , Yoshino Katsumi 
Published: September 2002

Abstract
A composite of polyaniline (PANI) encapsulating titanium oxide (TiO2) with nanometer size has been synthesized by in-situ emulsion polymerization. Particle dimensions have been measured and the nature of the association between the components have been observed using SEM and TEM techniques. The interaction between PANI and TiO2 and the nature of chain growth have been investigated and explained according to the results of FTIR. The improvement of thermal stability and crystallinity of nanocomposites have been evaluated by using TGA and XRD. The mechanism of charge transport in these composites has also been studied by measuring the DC conductivity of all samples and the temperature-conductivity relation. The photoconductivity of PANI-TiO2 composite has been enhanced markedly. This effect is discussed by taking the photoinduced charge transfer between PANI and TiO2 into consideration.
Preparation of Cinchonidine-Modified Palladium Catalysts for the Enantioselective Hydrogenation of (E)-α-Phenylcinnamic Acid
Authors: Nitta Yuriko , Kubota Takeshi , Okamoto Yasuaki 
Published: September 2002

Abstract
The enantioselective hydrogenation of the C=C double bond in (E)-α-phenylcinnamic acid has been studied with different supported Pd catalysts prepared by a precipitation-deposition method and modified with cinchonidine. The influences of the support materials and the texture, Pd loadings, precipitation procedures, and reduction conditions on the hydrogenation activity and enantioselectivity are described. The texture of the supports has a decisive influence on the behavior of the resulting catalysts, especially when it is pre-reduced at elevated temperatures. Nonporous titania with a relatively small specific surface area was found to be the most suitable. The use of a large excess amount of precipitant resulted in an increase in the amount of residual Na and in a drastic decrease in the amount of residual Cl, leading to a remarkable increase in the activity. The elimination of both the residual Na and Cl from the catalyst precursor was found to be preferable for the enantioselectivity. A considerable increase in the enantioselectivity was observed when a 5wt%Pd/TiO2 catalyst, prepared with nonporous titania, was reduced in a hydrogen flow at elevated temperatures up to 473 K. The influences of the surface area of nonporous supports, Pd loadings, and reduction conditions strongly suggest that the enantioselectivity of the modified Pd/TiO2 catalysts depends on the Pd dispersion; a relatively low dispersion around 0.2—0.3 was found to be optimal.
Reflection Spectroscopic Study of Organic Conductors
Authors: Yakushi Kyuya 
Published: September 2002

Abstract
The author reviews the low-energy optical transitions in quasi one- and two-dimensional organic conductors studied by polarized reflection spectroscopy. The characteristic optical properties of organic conductors are the strong anisotropy, electron-electron interaction, and coupling with intra-molecular vibration. The method to extract the transfer integrals in anisotropic tight-binding bands is described for several organic conductors. The correlation effect has a big influence on the line shape of the optical conductivity spectrum in the intra-band transition region. The electron-molecular vibration coupling provides us with rich information on the structural fluctuations and structural changes during the phase transition. The observation of plasmons resulting from the mixing with the transverse excitation is caused by the strong anisotropy in electronic structure.
Optical Oxygen Sensing Based on the Luminescence Quenching of Europium(III) Complex Immobilized in Fluoropolymer Film
Authors: Amao Yutaka , Okura Ichiro , Miyashita Tokuji 
Published: September 2002

Abstract
New optical oxygen sensors based on the luminescence intensities of four different europium(III) complexes, ((1,10-phenanthroline)tris(thenoyltrifluoroacetonato)europium(III) complex ([Eu(tta)3phen]), tris(thenoyltrifluoroacetonato)europium(III) dihydrate ([Eu(tta)3]·2H2O), tris(1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionato)europium(III) complex ([Eu(pta)3]·2H2O) and tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionato)europium(III) complex ([Eu(fod)3]·2H2O)) immobilized in poly(styrene-co-2,2,2-trifluoroethyl methacrylate) (poly-(styrene-co-TFEM)) films were developed. The luminescence intensity of the europium(III) complex films decreased with increasing the oxygen concentration. Stern-Volmer plots of the europium(III) complex films exhibited considerable linearity. The KSV values of [Eu(tta)3phen], [Eu(tta)3]·2H2O, [Eu(pta)3]·2H2O and [Eu(fod)3]·2H2O in films were estimated to be 0.015, 0.005, 0.002 and 0.003 %-1, respectively. The large KSV value of the [Eu(tta)3phen] film was obtained compared with the other europium(III) complexes. The response times of the europium(III) complex films are 6.7 s for [Eu(tta)3phen], 6.7 s for [Eu(tta)3]·2H2O, 6.6 s for [Eu(pta)3]·2H2O and 7.6 s for [Eu(fod)3]·2H2O on going from argon to oxygen and 7.0 s for [Eu(tta)3phen], 7.5 s for [Eu(tta)3]·2H2O, 8.1 s for [Eu(pta)3]·2H2O and 8.6 s for [Eu(fod)3]·2H2O on going from oxygen to argon, respectively. A highly sensitive oxygen sensor using [Eu(tta)3phen] immobilized in poly-(styrene-co-TFEM) film has been developed.
Energetics for the Oxygen Rebound Mechanism of Alkane Hydroxylation by the Iron-Oxo Species of Cytochrome P450
Authors: Yoshizawa Kazunari , Shiota Yoshihito , Kagawa Yoshihisa 
Published: September 2002

Abstract
Density-functional-theory calculational results on the reaction pathway for alkane hydroxylation by a compound I model of cytochrome P450 are discussed. Our calculations demonstrate that the transition state for the H-atom abstraction of ethane involves a linear (Fe)O…H…C array and that the resultant carbon radical is bound to the iron-hydroxo species. This comptational result is partly consistent with the oxygen rebound mechanism in that the direct H-atom abstraction by the iron-oxo species takes place in the initial stages of the reaction pathway. However, the iron-hydroxo species cannot be viewed as a stable reaction intermediate in view of the energy diagram. Our results may not be consistent with the model of a free radical species with a finite lifetime and barrier to displacement of the OH group from the iron center that is commonly assumed and typically stated for the oxygen rebound mechanism.
Triplet Energy Transfer and Triplet Exciplex Formation of Benzophenone
Authors: Shizuka Haruo , Yamaji Minoru 
Published: September 2002

Abstract
Photochemical and photophysical aspects of (1) triplet energy transfer (TET) from triplet benzophenone (BP) to naphthalene derivatives (NpD) and (2) formation and decay processes of triplet exciplexes between 3NpD* and BP have been studied by 355-nm laser photolysis techniques in the liquid phase. As an initial event, TET occurs from 3BP* to NpD competing with H-atom transfer (HT), electron transfer (ET), and induced quenching (IQ) on the nanosecond time scale. The TET rate constant increases with an increase of solvent polarity while that of HT decreases, indicating that the 3(n, π*) state of BP is slightly mixed with 1(π, π*) in polar media. After formation of 3NpD* by TET from 3BP*, chemical reactions via triplet exciplexes between 3NpD* and BP having loose sandwich-like structures with weak charge transfer character take place in the microsecond time scale, depending on the substituent groups of NpD. (1) HT from triplet 2-naphthylammoniun ion and triplet naphthol to BP occurs efficiently to yield the 2-naphthylamine cation radical and naphthoxy radical plus the benzophenone ketyl radical, respectively. The more protic H-atom in NpD is the more reactive in HT. (2) The proton-induced ET from triplet methoxynaphthalene to BP takes place effectively via the protonated triplet exciplex to give the methoxynaphthalene cation and benzophenone ketyl radical. (3) Hydrogen bonding-induced ET from triplet N, N-dialkyl-1-naphthylamine to BP occurs to yield the N-dialkyl-1-naphthylamine cation radical and benzophenone anion radical in the presence of protic solvents.
Phase Transfer of Gold Nanoparticles across a Water/Oil Interface by Stoichiometric Ion-Pair Formation on Particle Surfaces
Authors: Yao Hiroshi , Momozawa Osamu , Hamatani Tomoki , Kimura Keisaku 
Published: September 2002

Abstract
The transfer of surface-modified gold nanoparticles across a water/toluene interface was demonstrated. Stoichiometric ion-pair formation between carboxylate anions on particle surfaces and tetraoctylammonium cations brought about the phase transfer, and was revealed by transmission electron microscopy (TEM), IR, UV-vis absorption, and energy dispersive X-ray (EDX) spectroscopies. A surface structure of the transferred gold nanoparticles was also presented. During the nanoparticle transfer from water into an organic phase, an improvement in the dispersibility and a slight decrease in the average diameter were observed (3.6 → 2.9 nm) accompanied by a slight narrowing in the size distribution (standard deviation: 0.80 → 0.54 nm). The phenomena could lead to a new methodology for size and/or dispersibility selections.
Systematic Design of Chiral Molecules of High Symmetry. Achiral Skeletons Substituted with Chiral Ligands
Authors: Fujita Shinsaku 
Published: September 2002

Abstract
For the design of chiral molecules of high symmetry, a set of substitution positions in an achiral skeleton of G-symmetry are replaced by chiral ligands or proligands of the same kind so that there emerge three criteria of generating chiral molecules or promolecules. Thus, Criterion 1 controls the desymmetrization of a homospheric orbit in an achiral skeleton, where the resulting molecule or promolecule is determined to belong to the maximum chiral subgroup of G in agreement with a size-invariant subduction. Criterion 2 for the desymmetrization of an enantiospheric orbit shows that the resulting molecule or promolecule is determined to belong to the maximum chiral subgroup of G and that the original enantiospheric orbits are divided into two hemispheric orbits of equal size. Criterion 3 deals with a chiral skeleton, where subsitution by chiral ligands or proligands of the same kind is examined as the transformation of the hemispheric orbit in the skeleton. Although no change of symmetry occurs from a group-theoretical point of view, the transformation is shown to be important chemically, since relevant ligands or proligands alter the stereochemical properties.
NMR Study of Hydrothermal Reactions of Dichloromethane with and without Alkali
Authors: Yamasaki Yuki , Enomoto Heiji , Yamasaki Nakamichi , Nakahara Masaru 
Published: September 2002

Abstract
Hydrothermal reactions of considerably concentrated (ca. 1 M; M = mol dm-3) dichloromethane, CH2Cl2, were investigated with and without alkali in the temperature range of 150—300 °C by using batch reactors, such as an autoclave and sealed glass tubes. 1H, 2H, and 13C NMR spectra were taken at room temperature as a function of reaction time to analyze the quenched reactants, intermediates, and products. In the presence of NaOH at 2 M, the complete dechlorination was achieved in 270 min at 250 °C and in 60 min at 300 °C. Such gaseous by-products as CO, CO2, and H2 were generated by the decomposition of the disproportionation product, HCOO-. Without alkali, CH2(OH)2 could be detected by 1H and 13C NMR as an intermediate in the hydrolysis of CH2Cl2, before such Cannizzaro products as methanol and formate ion were formed. The mechanism of the hydrothermal reactions of CH2Cl2 is discussed in terms of the hydrolysis intermediate, CH2(OH)2.
An OH Monitoring Method Using Infrared-Ultraviolet Double Resonance Laser-Induced Fluorescence
Authors: Tsuji Kazuhide , Nakata Kiyoshi , Oishi Hirotada , Shibuya Kazuhiko 
Published: September 2002

Abstract
We have applied an infrared-ultraviolet double resonance laser-induced fluorescence (IR-UV LIF) technique to the measurement of OH concentrations in the troposphere. This OH exists in extremely low concentrations, ca. 106 molecules cm-3, and plays a central role in the atmospheric chemistry. The detection limit of this new technique using our laser and detection system was experimentally determined to be 1.3×109 molecules cm-3 at 9.2 mTorr in Ar buffer gas. We have found that the method is free from chemical interferences but less sensitive than the single photon LIF method. A simple model is formulated and differential equations are numerically solved after the selection and determination of necessary physical constants. The method leads to the simulated (single photon LIF)/(IR-UV LIF) sensitivity ratio of 1.4×103, comparable with the experimental value of 2.2×103. On the basis of the proposed kinetic model, we discuss the optimum experimental parameters (sample pressure, IR and UV laser powers, and delay time) in this IR-UV LIF method by taking account of rotational energy transfer, fluorescence quenching, and saturation of absorption.
Mass-Spectrometric Study on Ion-Molecule Reactions of CH5+, C2H5+, and C3H5+ with C8—C18 n-Paraffins in an Ion Trap
Authors: Tanaka Yuki , Tsuji Masaharu , Nishimura Yukio 
Published: September 2002

Abstract
Chemical ionization of n-paraffins (CxH2x+2: x = 8—18) by the CH5+, C2H5+, and C3H5+ ions has been studied under a reactant-ion selective mode of an ion-trap type of GC/MS. In all the reactions, (MW-1)+ = CxH2x+1+ and fragment alkyl CyH2y+1+ (y = 3—x - 3) ions were observed. The dependence of the relative intensities of CxH2x+1+ and CyH2y+1+ on the reaction time indicated that collisional stabilization takes part in the formation of product ions. The dependence of CxH2x+1+ and CyH2y+1+ distributions on the reactant hydrocarbon ions and reagent chain length was examined. The reaction mechanism was discussed from the observed product-ion distributions and heats of reactions of each pathway.
Twist Phase Transition in Poly(p-phenylene) Oligomers: Heat Capacity of p-Quinquephenyl
Authors: Saito Kazuya , Yamamura Yasuhisa , Sorai Michio 
Published: September 2002

Abstract
The heat capacity of crystalline p-quinquephenyl was measured by adiabatic calorimetry below room temperature. A broad hump was detected around 264 K and attributed to a phase transition, through which an average molecular conformation changes from the planar to the twisted one on cooling. A similar anomaly was also detected for crystalline p-sexiphenyl around 295 K by chopped-light ac calorimetry. The broad shape of the thermal anomalies arising from the twist transitions are discussed in relation to the number of possible intramolecular twisting modes. Properties of the twist transition in polymer are discussed on the basis of those of oligomers. Standard thermodynamic functions are tabulated for p-quinquephenyl.
Electron-Beam Decomposition of Carbon Tetrachloride in Air/Nitrogen
Authors: Hirota Koichi , Arai Hidehiko , Hashimoto Shoji 
Published: September 2002

Abstract
Carbon tetrachloride (CCl4, approximately 10, 50, and 100 ppm) in air and nitrogen was irradiated with electron beams in both the presence and absence of water. The absorbed doses ranged from 1.2 to 18.0 kGys. An absorbed dose of 18 kGy led to approximately 90% decomposition of CCl4 at a concentration of 10 ppm in dry air. The presence of water lowered the decomposition rate in air by 20%, but not in nitrogen. Negative oxygen ions (O2-) formed upon the irradiation of wet air played a role in the oxidation of CCl4. Water molecules became negative cluster ions (O2-(H2O)n) with negative oxygen ions, which depressed the oxidation.
Crystal Structure of N,N′-Distearyl-1,4-diazabicyclo[2.2.2]octane Dibromide
Authors: Ishioka Tsutomu , Matsuda Noriko , Kitagawa Yasuyuki , Nakamura Kazuo T 
Published: September 2002

Abstract
The crystal structure of N,N′-distearyl-1,4-diazabicyclo[2.2.2]octane dibromide is orthorhombic (Pna21) with a = 63.851(9), b = 9.156(7), c = 8.366(6) Å and Z = 4.
References for NMR Chemical Shift Measurements in Cyclodextrin Solutions
Authors: Funasaki Noriaki , Nomura Masao , Yamaguchi Hiroshi , Ishikawa Seiji , Neya Saburo 
Published: September 2002

Abstract
Sodium methanesulfonate and sodium methyl sulfate are good internal references for chemical shift determination in aqueous solutions containing cyclodextrin and anionic guests. The chemical shift, referred to external standard and corrected by adding a term proportional to the cyclodextrin concentration, is in excellent agreement with that obtained using internal standard.
Transport Behavior of Amino Acid across Charged Mosaic Membrane
Authors: Fukuda Takashi , Yamauchi Akira 
Published: September 2002

Abstract
Several characteristics on a charged mosaic membrane with parallel arrays of different negative and positive charges were investigated through transport studies. In particular, the transport behaviors of three different amino acids (GluNa, Arg, and Ala), known as amphoteric electrolytes, were examined in contrast to those of the simple electrolytes (KCl and LiCl). From an analysis of the data of the volume flux and salt flux, although preferential amino acid transport across the charged mosaic membrane was observed, the extent of the permeability was less than that of simple salt. Among amino acids, GluNa with almost complete dissociation indicated the maximum permeability. A conductance study indicated that the transport behaviors were dependent on the ionic states in aqueous solution. It was inferred that amino acids with apparent zero net charges have transport behaviors different from a nonelectrolyte, such as sucrose.
Structures of [M(cbim)4(NO3)2] [M = Cd(II), Co(II) and Ni(II); cbim = 4′-Cyanobenzyl-1-imidazole] in the Solid State and in Solution
Authors: Sun Wei-Yin , Fei Bao-Li , Okamura Taka-aki , Zhang Yan-An , Ye Tao , Tang Wen-Xia , Ueyama Norikazu 
Published: September 2002

Abstract
Mononuclear complexes, [M(cbim)4(NO3)2] [M = Cd(II) (1), Co(II) (2) and Ni(II) (3); cbim = 4′–cyanobenzyl–1–imidazole], were synthesized and their structures were determined by X-ray crystallography. Each metal atom is coordinated by four N atoms of imidazole from four cbim ligands and two O atoms of two nitrate anions with distorted octahedral coordination geometry. All three complexes crystallize in triclinic with space group P1. There are C-H···O, C-H···N hydrogen bonds and π-π interactions in the crystal packing of complexes 1, 2, and 3. The compounds were also characterized by 1H and 113Cd NMR spectroscopy. Highly isotropic shifted signals were observed in the 1H NMR spectra of complexes 2 and 3 due to the paramagnetic property of the high-spin Co(II) and Ni(II) cores.
The Role of Activated α-Carbon Atom Hydrogen in Salting-in Effect on Tris(α-amino acidato)cobalt(III)
Authors: Yoshimura Yasuki 
Published: September 2002

Abstract
In order to examine the role of activated α-carbon atom hydrogen of α-amino acid in the salt effect on tris(α-amino acidato)cobalt(III) ([Co(aa)3]), the solubilities of mer- and fac-tris(2-aminoisobutyrato)cobalt(III) (mer- and fac-[Co(aiba)3]) in water and in aqueous NaBr and tetrabutylammonium bromide (Bu4NBr) solutions were determined over the temperature range 5 to 40 °C. From these solubility data, the standard enthalpy (ΔtrH0) and entropy of transfer (ΔtrS0) at 25 °C for mer- and fac-[Co(aiba)3] from water to the aqueous NaBr and Bu4NBr solutions were estimated. A comparison with the ΔtrH0 and TΔtrS0 data for mer-[Co(aa)3] of L-leucine (leuH), L-alanine (alaH), and glycine (glyH) shows that both ΔtrH0 and TΔtrS0 for the transfer of mer-[Co(aa)3] to the NaBr solutions are negative; the large negative ΔtrH0 increases the solubility of mer-[Co(aa)3] (salting-in effect). Both ΔtrH0 and TΔtrS0 decrease in the order of mer–[Co(aiba)3] &gt; mer–(+)–[Co(L–leu)3] &gt; mer–(+)–[Co(L–ala)3] &gt; mer–[Co(gly)3]. This sequence is explained by the assumption that activated α-carbon atom hydrogen enhances interactions of mer-[Co(aa)3] with the surroundings. The effect of Bu4NBr can be accounted for by hydrophobic interaction of [Co(aiba)3] with Bu4N+ ion and the hydrophobic interaction of fac-[Co(aiba)3] is larger than the interaction of mer-[Co(aiba)3].
Dependence of EXAFS (Extended X-Ray Absorption Fine Structure) Parameters of Iodide Anions in Various Solvents upon a Solvent Parameter
Authors: Tanida Hajime , Watanabe Iwao 
Published: September 2002

Abstract
X-ray absorption spectra of I K-edge have been obtained for iodide ions dissolved in various solvents. Oscillation amplitudes of the extended X-ray absorption fine structure (EXAFS) evaluated from the peak intensities in the Fourier-transform spectra were found to correlate with the Mayer-Gutmann acceptor number (AN) of solvents studied. The correlation is quite similar to that for bromide ions, which has already been reported by the same authors (H. Tanida, H. Sakane, and I. Watanabe, J. Chem. Soc., Dalton Trans., 1994, 2321). Such results confirm that the EXAFS method is not only a tool to determine geometrical structures in liquids, but can also be used for evaluating solute-solvent interaction strength, similarly to AN. The I…O distances in protic solvents and I…C in aprotic solvents were determined to be 3.4—3.5 and 3.7—3.8 Å, respectively. In protic solvents, the larger the AN values, the shorter the I…O distances and the larger the co-ordination numbers of I-, which were determined to be 1—4. In aprotic solvents, the co-ordination numbers of I- were found to be 4—8. It seems that aprotic solvents having two methyl groups in a molecule are able to solvate I- through two methyl groups, which is similar to the conclusion reported for Br-.
Anomalous Electrochemical Behavior of 1,4-Benzoquinone upon the Addition of Silver Ion
Authors: Ando Isao , Miyake Hiroto , Ohki Yusuke , Ujimoto Kikujiro , Kurihara Hirondo 
Published: September 2002

Abstract
A cyclic voltammogram of 1,4-benzoquinone showed a couple of redox waves in aqueous solution. Upon adding a trace amount of silver ion, the cyclic voltammogram exhibited an anomalous behavior: a shift of the reduction peak toward a negative potential and the appearance of a new re-oxidation peak at a much more positive potential. This anomalous electrochemical behavior was investigated in terms of both interactions in bulk and on the electrode surface using some kinds of metal-ion additives and some working-electrode materials. It is suggested that the underpotential deposition of silver ion is primarily responsible for the anomalous electrochemical behavior of 1,4-benzoquinone. This was demonstrated by a measurement of cyclic voltammograms using a silver-deposited electrode at an underpotential.