bluuebunny/crossref_metadata_2025 huggingface dataset:
The Ion-Exchange Property of Some Layered Inorganic Materials with Potassium Ion, Rubidium Ion and Cesium Ion, and Selective Cesium Ion-Exchange of Synthetic Mica
Authors: Suzuki Noriko , Yamamoto Daisuke , Anaguchi Noriko , Tsuchiya Hiroko , Aoki Kumi , Kanzaki Yasushi
Published: September 2002

The ion-exchange property of sodium difluorotetrasilicate, Na-TSM, with potassium, rubidium and cesium ions was investigated in addition to two other typical layered inorganic materials. The selectivity sequence of Na-TSM was Cs+ > Rb+ > K+ and the selectivity difference of Na-TSM was highest among the examined layered materials. It was found from a chemical analysis that cesium ion-exchange participated in magnesium ions, which is a lattice component of Na-TSM, in addition to an ordinary ion-exchange reaction with the interlayer sodium ions. The exchange of cesium ions with magnesium ions was found to be stoichiometric, and was expected to be an ideal ion-exchange reaction. It was a peculiar phenomenon only on Na-TSM. Once cesium ions were exchanged in a Na-TSM lattice, they were hardly released, due to a reverse ion-exchange with sodium ions. The highest selectivity difference and tight binding of cesium ions were interpreted by an ion-exchange with lattice magnesium ion as well as decreased dehydration, which resulted in the interlayer gallery height.
Synthesis and Characterization of Titanium-Containing Mesoporous Silica by a Non-Hydrothermal Microwave Method
Authors: Belhekar Anagha , Agashe Mangala , Soni Hirji , Sathaye Shivaram , Jacob Nalini , Thundimadathil Jyothi
Published: September 2002

We report on a new method for preparing mesoporous silica and titanium-containing mesoporous silica using microwave (MW) synthesis under non-hydrothermal conditions. The materials were characterized by XRD, nitrogen adsorption, UV-vis and FTIR techniques, and compared with a sample prepared by the conventional method. A single peak at 2θ = 2.4° in the XRD pattern showed the formation of mesoporous silica. A typical isotherm, characteristic of a mesoporous material where pore filling occurred at p/p0 in the range of 0.2—0.3 was obtained for nitrogen sorption. UV-vis diffused reflectance spectra showed bands at 210—220 nm and a shoulder at 270 nm, indicating the presence of Si-O-Ti bonds for titanium-containing mesoporous silica. This new method has been observed to have inherent advantages over reported methods, such as instant start up, a short heating time and low cost. These mesoporous titanosilicates prepared using a microwave heat energy source are active in the oxidation of 2,6-diisopropylphenol (DIPP) and 2,6-di-t-butylphenol (DTBP) with hydrogen peroxide as an oxidant.
Dye-Sensitized Photocells with Meso-Macroporous TiO2 Film Electrodes
Authors: Ito Seigo , Ishikawa Keiji , Wen Ching-Ju , Yoshida Shoichiro , Watanabe Tadashi
Published: September 2002

Meso-macroporous anatase TiO2 films, described in a previous work, have been used for the first time as electrodes for dye-sensitized photoelectrochemical cells. The mesopores provide a large surface area that is favorable for efficient light absorption, and the macropores serve as pathways for diffusion of electroactive agents (EAAs). Although the introduction of macropores led to an improvement in the magnitude of the short-circuit photocurrent (Jsc), electron recombination on the SnO2 substrate surface at the bottom of the macropores deteriorated the open-circuit voltage (Voc). This unfavorable process has been depressed by applying a thin (200 to 300 nm) TiO2 film between the meso-macroporous film and the SnO2 substrate, to obtain finally a dye-sensitized photoelectrode with a Voc nearly identical with, and a Jsc superior to, the values for a conventional porous TiO2 film electrode.
Formation of Cylindrical-Shaped Coordination Polymer by Self-Assembling of 2, 2, 4, 4, 6, 6-Hexakis(4-pyridylmethoxy)-2λ5, 4λ5, 6λ5-cyclotri(phosphazene) with Silver Nitrate
Authors: Itaya Tomoyuki , Inoue Kenzo
Published: September 2002

The self-assembling of 2, 2, 4, 4, 6, 6-hexakis(4-pyridylmethoxy)-2λ5, 4λ5, 6λ5-cyclotri(phosphazene) (PyPN) and AgNO3 in DMSO gives a white rod-shaped coordination polymer. FT-IR and X-ray absorption fine structure spectra, X-ray diffraction data, and elemental analysis showed that the coordination polymer takes a cylindrical structure and is laterally packed into a hexagonal arrangement.
Evaluation of Synthesized Lacquer Films Using Pyrolysis-Gas Chromatography/Mass Spectrometry
Authors: Kamiya Yukio , Niimura Yasunori , Miyakoshi Tetsuo
Published: September 2002

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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] > mer–(+)–[Co(L–leu)3] > mer–(+)–[Co(L–ala)3] > 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

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

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.
Unique Aspects of the 1-Methylimidazole Ligation to Corrphycenatoiron(III)
Authors: Neya Saburo , Ohgo Yoshiki , Nakamura Mikio , Funasaki Noriaki
Published: September 2002

The coordination behaviors of chloro corrphycenatoiron(III), a novel hemin isomer with a trapezoidal metallo core, against imidazole, 1-methylimidazole, and 2-methylimidazole were followed by spectrophotometry in chloroform at room temperature. The examined compound is chloro 12,17-bis(ethoxycarbonyl)-2,3,6,7,11,18-hexamethylcorrphycenatoiron(III). Titration of 2-methylimidazole and imidazole proceeded with and without accumulation of an intermediate mono imidazole species, respectively. On the other hand, a significant amount of an intermediate adduct was found to accumulate during 1-methylimidazole binding despite the absence of any steric hindrance in the iron(III)-N(1-methylimidazole) coordination bond. This is in remarkable contrast with the conventional results for porphyrinatoiron(III). The proton NMR analysis of the mono 1-methylimidazole binding to corrphycenatoiron(III) afforded a formation constant closely similar to that obtained from the visible spectra. EPR definitely assigned the iron(III) high-spin state for the intermediate. Accumulation of the mono 1-methylimidazole intermediate was explained in terms of the contracted core in corrphycene. The narrow iron cavity weakens the axial iron-chloride bond facilitating coordination of the first 1-methylimidazole. The four non-orthogonal iron(III)-N(pyrrole) bonds formed in the trapezoidal cavity further disturb the incoming motion of the iron(III) atom into corrphycene plane upon second 1-methylimidazole ligation. Accumulation of mono 1-methylimidazole intermediate was more evident in ferric corrphycenatoiron(III) with bromide and iodide, supporting the proposed changes in iron reactivity upon deformation of the equatorial coordination environment.
Five-Coordinate Geometry of Cadmium(II) with Octahedral Bidentate-S,S Complex-Ligand cis(S)-[Co(aet)2(en)]+ (aet = 2-aminoethanethiolate): Synthesis, Crystal Structures and Interconversion of S-Bridged CoIIICdII Polynuclear Complexes
Authors: Konno Takumi , Tokuda Keiji , Sakurai Junko , Okamoto Ken-ichi
Published: September 2002

An S-bridged CoIIICdII dinuclear complex molecule, [CdCl3{Co(aet)2(en)}]0 ([1]) (aet = 2–aminoethanethiolate, en = ethylenediamine), was prepared by the reaction of an S-bridged CoIIINiIICoIII trinuclear complex salt, [Ni{Co(aet)2(en)}2]Cl4, with excess CdCl2 in water. Treatment of [1] with NaNO3 in water gave an S-bridged CoIIICdIICoIII dinuclear complex salt, [CdCl{Co(aet)2(en)}2](NO3)3 ([2](NO3)3), which was further converted to a (CoIIICdIICoIII)2 hexanuclear complex salt, [Cd2Cl{Co(aet)2(en)}4](NO3)7 ([3](NO3)7), by treatment with NaNO3 in water. The crystal structures of [1], [2](NO3)3 and [3](NO3)7 were determined by X-ray crystallography. In [1] CdII ion is coordinated by three Cl- ions besides two S atoms from one octahedral C2-cis(S)-[Co(aet)2(en)]+ unit, while each CdII ion in [2]3+ and [3]7+ is coordinated by one Cl- ion besides four S atoms from two C2-cis(S)-[Co(aet)2(en)]+ units. The coordination geometry of each CdII center in [1], [2]3+ and [3]7+ is described as a distorted trigonal-bipyramid, considering an angular structural parameter, χ, which is proposed as a modified index of trigonality. The reverse conversions of [3]7+ to [2]3+ and [2]3+ to [1] were also achieved by treatment with NaCl in water.
Selective, Convenient and Efficient Deprotection of Trimethylsilyl and Tetrahydropyranyl Ethers, Ethylene Acetals and Ketals with Oxone under Non-aqueous Conditions
Authors: Mohammadpoor-Baltork Iraj , Amini Mohammad Kazem , Farshidipoor Siyamak
Published: September 2002

An efficient and selective method for the deprotection of trimethylsilyl (TMS) and tetrahydropyranyl (THP) ethers, ethylene acetals and ketals to their corresponding alcohols and carbonyl compounds using oxone in refluxing acetonitrile is described. Excellent chemoselectivity of this method makes it a useful and practical procedure in organic synthesis.
Rhenium Complexes-Catalyzed Alkylation of Arenes with Alkyl Halides
Authors: Nishiyama Yutaka , Kakushou Fujio , Sonoda Noboru
Published: September 2002

Rhenium complexes have been shown to catalyze the alkylation of arenes with alkyl halides. When arenes were reacted with an alkyl chloride in the presence of a catalytic amount of rhenium complexes, such as bromopentacarbonylrhenium(I) [ReBr(CO)5], tricarbonylcyclopentadienylrhenium(I) [Re(C5H5)(CO)3] and decacarbonyldirhenium [Re2(CO)10], alkylation of the arenes proceeded under mild conditions to give a mixture of mono- and dialkyl substituted arenes in moderate-to-good yields.
Mechanistic Studies of the Pyrene-Sensitized Photodecomposition of N-Phenylglycine: Acceleration of the Photodecomposition by the Addition of an Electron Acceptor
Authors: Ikeda Shingo , Murata Shigeru , Ishii Kunihiko , Hamaguchi Hiro-o
Published: September 2002

The processes of the pyrene-sensitized photodecomposition of N-phenylglycine (NPG) have been investigated by fluorescence quenching experiments, laser flash photolysis studies, and characterization of the reaction products. A mechanism involving electron transfer from NPG to singlet excited pyrene through emissive exciplex formation, as well as the intervention of PhNHCH2· as a reactive intermediate, has been established. The efficiency of NPG photodecomposition is enhanced by the addition of an electron acceptor, such as terephthalonitrile or diethyl isophthalate. The laser flash photolysis studies have revealed that the mechanism for the rate enhancement of NPG photodecomposition depends on the acceptor employed as an additive.
Lead(IV) Oxide-Mediated Oxidation of Azulen-2-ols to Form 1,1-Coupled Dimers and Hexacyclic Cage-Dimers.
Authors: Lin Yun-Shan , Lin Shih-Jue , Jiang Shuan-Ya , Huang Tian-Chyuan , Huang Chien-Yu , Kurihara Teruo , Mori Akira , Morita Tadayoshi , Takeshita Hitoshi , Nozoe Tetsuo
Published: September 2002

The lead(IV) oxide oxidation of various azulen-2-ol derivatives in acetic acid generates azulenoxy radicals via one-electron oxidation. The intermediates end up yielding recombined dimers, [1,1′-biazulene]-2,2′(1H,1′H)-dimers, as common type of products. In addition to these, hexacyclic cage dimers were obtained from 5-substituted azulen-2-ol derivatives. From dimethyl 2-hydroxyazulene-1,3-dicarboxylate, a hydroxyazulene having no substituent on the seven-membered ring was isolated a pair of dimethyl 2-hydroxy-4-[1,3-di(methoxycarbonyl)-2-oxo-1,2-dihydroazulenyl]azulene-1,3-dicarboxylate, but neither a cage dimer nor a 1,6-coupled dimer. The full structures of the dimers have been firmly established by an extensive X-ray crystallographic analysis and 13C NMR spectral comparisons of the key derivatives. Concerning the mechanism of the formation of the cage dimers, a [5+5] π cycloaddition followed by recombination of the resultant biallyl system is suggested.
Direct Synthesis of N-Hydroxy β-Amino Acid Esters from Carboxylic Esters and Nitrones
Authors: Kobayashi Kazuhiro , Matoba Takeshi , Irisawa Susumu , Takanohashi Atsushi , Tanmatsu Miyuki , Morikawa Osamu , Konishi Hisatoshi
Published: September 2002

The direct synthesis of the title amino acid derivatives from carboxylic esters and nitrones can be achieved in fair to good yields when lithium or magnesium ester enolates were treated with nitrones in THF at -78 °C or in Et2O at -20 to 0 °C, respectively. The products from the reaction of t-butyl acetate with 3,4-dihydroisoquinoline N-oxide or 5,5-dimethylpyrroline 1-oxide were transformed into (1,2,3,4-tetrahydroisoquinolin-1-ylidene)acetate or (pyrrolidin-2-ylidene)acetate derivatives in the presence of triphenylphosphine, carbon tetrachloride, and triethylamine in refluxing dichloromethane.
Solution Properties of Sodium Dodecylbenzenesulfonate (SDBS): Effect of Additives
Authors: Sulthana Shireen Basheer , Bhat Sodankoor Garadi Thirumaleshwar , Rakshit Animesh Kumar
Published: September 2002

The solution properties of sodium dodecylbenzenesulfonate (SDBS) in an aqueous medium in the presence of additives, like polyethylene glycol 400 (PEG 400), sucrose, and urea, have been investigated. The critical micelle concentration (cmc) was determined by both surface-tension and conductivity methods. The cmc values were found to increase along with an increase in the temperature in both the presence and absence of additives at all of the concentrations studied. The interfacial parameters, such as the maximum surface excess (Γmax) and minimum area per molecule (Amin), were computed from surface-tension data. The thermodynamic parameters of micellization and adsorption at air/water interfaces were also evaluated. Other properties, such as the micellar aggregation number (Nagg), viscosity, foaming, wetting, and detergency by dye solubilization, were also studied.
A Convenient Method for the Preparations of Carboxamides and Peptides by Using Di(2-pyridyl) Carbonate and
O
,
O
′-Di(2-pyridyl) Thiocarbonate as Dehydrating Reagents
Authors: Shiina Isamu , Suenaga Yoshihito , Nakano Masakazu , Mukaiyama Teruaki
Published: September 2002

Preparations of carboxamides and peptides are performed in high yields from free carboxylic acids and amines by dehydration condensation using di(2-pyridyl) carbonate (DPC) or O,O′-di(2-pyridyl) thiocarbonate (DPTC) in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP). The formation of 2-pyridyl esters, key intermediates of the reaction, from carboxylic acids by using DPC proceeded faster than by using DPTC; therefore, the former carbonate is more efficiently employed in the above condensation reactions.
Syntheses of Optically Active Citronellol, Citronellal, and Citronellic Acid by Microbial Oxidation and Double Coupling System in an Interface Bioreactor
Authors: Oda Shinobu , Sugai Takeshi , Ohta Hiromichi
Published: September 2002

We have already reported that (RS)-citronellol [(RS)-1] can be optically resolved via a transacetylation with acetyl coenzyme A [acetyl-CoA] by the aid of alcohol acetyltransferase [AATFase] in Pichia kluyveri IFO 1165, which we have referred to as a double coupling system (E value, 30 to 40). In this system, although (R)-1 is obtained at over 98% ee, (S)-citronellyl acetate [(S)-2] is prepared at 70 to 80% ee. In this article, we report on the conversion of (R)-1 to (R)-citronellal [(R)-3] and (R)-citronellic acid [(R)-4] in high yield without racemization by the aid of Rhodococcus equi JCM 6817 and Geotrichum candidum JCM 01747, respectively. On the other hand, the low ee of (S)-1 (78% ee) prepared via the alkaline hydrolysis of (S)-2 is converted to optically active (S)-1 and (S)-4 in high yield with a repeated double coupling system with P. kluyveri IFO 1165 and via enantioselective oxidation with Candida viswanathii IFO 10321, respectively. Thus, five optically active terpenoids related to citronellol, except for (S)-3, were efficiently synthesized via microbial transformations in an interface bioreactor.
A General Method for the Formation of Zinc Enolate Equivalents from Iodoacetates by Diisopropylzinc-Iodine Exchange Reaction: Preparation of β-Hydroxy Esters
Authors: Sato Itaru , Takizawa Yoshiko , Soai Kenso
Published: September 2002

Diisopropylzinc is found to be a highly efficient reagent for the formation of zinc enolate equivalents from various iodoacetates via iodine-zinc exchange reaction at room temperature, affording β-hydroxy esters in high yields by the reaction with aldehydes and ketones.
Synthesis of Diarylsulfoximines by the Friedel-Crafts Reaction of Sulfonimidoyl Chlorides
Authors: Furusho Yoshio , Okada Yuichiro , Takata Toshikazu
Published: September 2002

In the presence of an equimolar amount of FeCl3, sulfonimidoyl chlorides were allowed to react with aromatic compounds to give the corresponding sulfoximines. Structure of the sulfonimidoyl chlorides and the aromatic compounds had considerable influence on the yield of the sulfoximines.
Construction of Polymeric Self-Assembly Based on 2λ5,4λ5,6λ5-Cyclotriphosphazene and Its Inclusion Behavior of Iodine
Authors: Itaya Tomoyuki , Inoue Kenzo
Published: September 2002

The self-assembling of 2,2,4,4,6,6-hexakis(4-pyridylmethoxy)-2λ5, 4λ5, 6λ5-cyclotri(phosphazene) (PyPN) and 1,4-naphthalenedicarboxylic acid (DCN) in DMF gives needle-like crystals. From elemental analysis, the stoichiometry of the crystal was PyPN/DCN = 1 : 3. The FT-IR, fluorescence and X-ray diffraction data showed that the self-assemblies [PyPN·3(DCN)]n (1) formed by the hydrogen bonding with an alternating sequence of one PyPN and three DCN molecules take a cylindrical structure and are laterally packed into a hexagonal arrangement, where the naphthalene rings are placed to avoid steric congestion. The assembly 1 has an ability to include iodine molecules. From FT-Raman spectroscopy, the iodine in 1 was found to exist as a polyiodine linear I5- ion, indicating that the crystal of 1 has a tunnel-like void.
Potential Energy Surfaces for Liquid Ammonia: An Estimation of ab initio Calculations for Molecular Simulations
Authors: Honda Kazuhiko
Published: September 2002

Hydrogen-bond-enhanced interactions were generated for ammonia pairs by ab initio calculations using tempered basis sets. The potential function obtained by the generation of interaction energies was applied to a Monte Carlo simulation for the liquid state of ammonia. The simulated bulk properties were considered compared with a previous ab initio STO-3G based simulation. The thermodynamic properties were obtained in the simulation and compared with those of a liquid water system to which the same manner of enhancement for the hydrogen bond was applied. The qualitative difference between the two liquids was reproduced.
Formation of an Iron-Oxo Species upon Decomposition of Dinitrogen Oxide on a Model of Fe-ZSM-5 Zeolite
Authors: Yoshizawa Kazunari , Yumura Takashi , Shiota Yoshihito , Yamabe Tokio
Published: September 2002

The so-called ``α-oxygen" on Fe-ZSM-5 zeolite, a surface oxygen species responsible for high reactivity in oxidation of methane and of benzene, has been investigated. We present from density-functional-theory (DFT) calculations how such a reactive surface species is generated upon decomposition of dinitrogen oxide (N2O) and propose a possible form of ``α-oxygen" on Fe-ZSM-5 zeolite. In the initial stages of the reactions, a complex involving an Fe(ON2) moiety is formed, followed by dissociation into an iron-oxo species and N2. The activation energy for the decomposition of N2O on a possible iron active site model of Fe-ZSM-5 zeolite is predicted to be 2.4 kcal mol-1 at the B3LYP level of theory. Therefore the decomposition of N2O is expected to take place easily at a coordinatively unsaturated iron active center supported on zeolite. The iron-oxo species thus formed should play an essential role in the direct hydroxylation of methane, benzene, and other hydrocarbons if it involves a coordinatively unsaturated iron. The oxygen exchange on the iron-oxo complex was also investigated. The activation energy for the oxygen exchange on the ``α-oxygen" is predicted to be 26.8 kcal mol-1. We propose that the bare FeO+ complex and the so-called ``α-oxygen" on Fe-ZSM-5 zeolite involve similar catalytic active centers responsible for similar catalytic functions for methane and benzene.
Quantum Mechanical Interpretation and Evaluation of Hydrogen Evolution at Metal Electrodes
Authors: Sakata Tadayoshi
Published: September 2002

The quantum mechanical theory of electrode reactions was applied to a hydrogen evolution reaction. The dependence of the activation energy of the hydrogen exchange current densities on the kind of electrode metal was explained well by this theory. The magnitude of the hydrogen exchange current densities and hydrogen overvoltages at various metal electrodes were evaluated theoretically. The calculated results and the dependency on the kind of metal were found to agree well quantitatively with the experimental values.
Cationic Motions and Order-Disorder Phase Transitions in Layer Crystals with a Rotator Phase, (n-C5H11NH3)2ZnCl4 and (n-C12H25NH3)2ZnCl4
Authors: Horiuchi Keizo , Takayama Himiko , Ishimaru Shin'ichi , Ikeda Ryuichi
Published: September 2002

1H NMR spin-lattice relaxation times T1 and T1ρ as well as the electrical conductivity were measured as a function of temperature in (n-C5H11NH3)2ZnCl4 and (n-C12H25NH3)2ZnCl4. The highest-temperature solid phase in both compounds was found to be the rotator phase, where rod-like cations perform uniaxial reorientations about the molecular long axes accompanied by conformational disordering and translational self-diffusion of the cations within the layer perpendicular to c-axis. In the rotator phase, the cations are considered to have a non-intercalated double layer structure. These rotator phases were shown to be quite analogous to those reported in n-alkylammonium chlorides. (n-C5H11NH3)2ZnCl4 undergoes four structural phase transitions, while (n-C12H25NH3)2ZnCl4 exhibits a single transition above ca. 120 K. All of these transitions were shown to be of order-disorder type.
Chemical Modification of MgO(001) Surface by Utilizing Energy Decomposition Analyses for the Purpose of CO2 Adsorption
Authors: Takahashi Hideaki , Okuda Kazuhiro , Nitta Tomoshige
Published: September 2002

The intermolecular interaction between a CO2 molecule and an MgO cluster has been investigated by ab initio molecular orbital method in order to test a selection rule for chemical modifications of surfaces. Favorable adsorption geometry has been determined by partial geometry optimizations initiated from three possible formations of the molecular complex. A CO3-form where the carbon atom is coordinated to an O atom of the MgO cluster is found to be most stable. The Kitaura-Morokuma energy decomposition analysis has been carried out to investigate the nature of the intermolecular interaction between a CO2 molecule and an MgO cluster. It is found that charge transfer energy from the MgO cluster to CO2 is the dominant component in the total stabilization energy. Two Mg atoms are replaced by two Ca atoms to enhance the electron flow from an MgO cluster to a CO2 molecule, which resulted in the increase in the adsorption energy. The effect of the chemical modification is examined by the energy decomposition analysis. We confirm that the increase of the cohesive energy is a consequence of the increase in charge transfer interaction from the cluster to the CO2 molecule. The mechanism of the charge transfer is also studied by the molecular orbital analysis.
Analysis of the Infrared Spectrum of RbCl Vapor
Authors: Ogilvie John F , Uehara Hiromichi , Horiai Koui
Published: September 2002

With laser diodes we measured spectra of RbCl vapor near 1000 K in absorption in a region 43800—46400 m-1 and assigned vibration-rotational transitions, 226 of 85Rb35Cl up to ν′ = 9 and J′ = 160, 158 transitions of 85Rb37Cl and 125 of 87Rb35Cl, all with Δν = 2. We made a global fit of these 509 new data plus 28 published pure rotational transitions. Of eight evaluated parameters, six are adjusted, pertaining to a function for potential energy, and two are constrained, pertaining to nonadiabatic rotational effects; these parameters suffice to reproduce these data generally within uncertainties of their measurement. Comparison is made with corresponding spectral parameters of HCl, LiCl, NaCl and KCl.
Generalization of Partial Cycle Indices and Modified Bisected Mark Tables for Combinatorial Enumeration
Authors: Fujita Shinsaku
Published: September 2002

Generalized partial cycle indices have been proposed as a generalization of partial cycle indices (PCIs) in order to enumerate isomers with a given set of subsymmetries. To evaluate the coefficient of each term appearing in such a generalized PCI, the natures of a mark table and of its inverse have been examined after the proposal of (modified) bisected mark tables and their inverses as well as of (modified) bisected tables of unit subduced cycle indices with chirality fittingness (USCI-CFs). The inverse of a (modified) bisected mark table and the (modified) bisected USCI-CF table have been applied to the enumeration of chiral isomers and achiral isomers.