Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 72 , Issue 9
Showing 1-27 articles out of 27 articles from the selected issue
  • Kazuhiko Ozutsumi, Hitoshi Ohtaki
    1999 Volume 72 Issue 9 Pages 1947-1956
    Published: 1999
    Released: December 10, 2004
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    Improvements of XAFS (X-Ray Absorption Fine Structure) measurements in the time domain are summarized and several examples of structure determination of reaction intermediates by the EXAFS (Extended X-Ray Absorption Fine Structure) method are given. The local structure around the copper(II) or cobalt(II) ion is described in the reaction intermediate in the metal substitution reaction of the homodinuclear mercury(II) porphyrinato (5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin; H6tpps) complex in an acetate buffer determined by the stopped-flow EXAFS (SF-EXAFS) method, which was developed by us. Comparison of the bond lengths in the intermediates with those in the reactants and the products of the metal substitution reaction, the structure of which has been determined by the same method, revealed the cause of the instability of the reaction intermediates.
  • Takashi Kyotani, Bhabendra Kumar Pradhan, Akira Tomita
    1999 Volume 72 Issue 9 Pages 1957-1970
    Published: 1999
    Released: December 10, 2004
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    A template carbonization technique was applied for synthesizing carbon nanotubes and metal filled nanotubes. An anodic aluminum oxide film that has uniform and straight channels with a diameter at nanometer level was used as a one-dimensional template. The pyrolytic carbon deposition on the channel wall was carried out by exposing the anodic oxide film to hydrocarbon gas at high temperature. The carbon was then liberated from the anodic oxide film by dissolving the alumina template. It was found that the resultant carbon is comprised only of uniform hollow-tubes with open ends. The length and the diameter of the carbon nanotubes are controllable by changing the length and the inner diameter of the channels in the anodic oxide film. By applying this template technique, metal filled uniform carbon nanotubes can also be fabricated. Pt, Ag, and Fe-filled carbon nanotubes were synthesized. If one varies metal the loading and metal reduction methods, various shapes of nano metal compounds can be inserted into the hollow of carbon nanotubes. It should be noted that no metal was observed on the outside walls of the tubes. The metal-filled uniform carbon nanotube thus prepared can be regarded as a novel one-dimensional composite, which has a variety of potential applications.
  • Takashi Nemoto, Yuji Ohashi
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 1971-1983
    Published: 1999
    Released: December 10, 2004
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    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.
  • Rimo Xi, Bateer Wang, Masaaki Abe, Yoshiki Ozawa, Isamu Kinoshita, Kiy ...
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 1985-1996
    Published: 1999
    Released: December 10, 2004
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    A new series of linear-type Mo2Rh2 tetranuclear complexes, [{Cp*RhIII(μ-SCH3)3MoVIO2}2(μ-O)] (1), [{Cp*RhIII(μ-SCH3)3MoVO}2(μ-O)2] (2), and [{Cp*RhIII(μ-SCH3)3MoVO}2(μ-O)(μ-S)] (3), has been prepared from reactions of the triple cubane-type oxide cluster [(Cp*Rh)4Mo4O16]·2H2O with CH3SH. These tetranuclear complexes have been characterized by elemental analysis, infrared, electronic, and 1H, 13C, and 17O NMR spectroscopies as well as X-ray analysis.
    Complex 1 crystallizes in the monoclinic space group P21/n (No. 14) with a = 15.348(3), b = 14.059(3), c = 17.879(3) Å, β = 107.11(2)°, V = 3690(1) Å3, and Z = 4. Complex 2 crystallizes in the monoclinic space group C2/c (No. 15) with a = 25.334(4), b = 21.271(2), c = 17.831(3) Å, β = 129.70(5)°, V = 7393(2) Å3, and Z = 8. Complex 3 crystallizes in the orthorhombic space group Pcab (No. 61) with a = 16.902(3), b = 26.631(3), c = 16.855(2) Å, V = 7587(3) Å3, and Z = 8. Complex 1 involves a nearly linear “O2MoVI(μ-O)MoVIO2” framework, to which two Cp*RhIII units are linked by μ-SCH3 ligands. Complexes 2 and 3 have an analogous tetranuclear MoV2RhIII2 structure in which the MoV and RhIII atoms are bridged by three μ-SCH3 ligands. Complex 2 contains a doubly-bridged “OMoV(μ-O)2MoVO” framework with an Mo–Mo distance of 2.564(1) Å, while 3 contains a “OMoV(μ-O)(μ-S)MoVO” framework with an Mo–Mo distance of 2.666(1) Å. Complexes 2 and 3 retain the tetranuclear structure but are fluxional in solution. The fluxional behaviors are due to intramolecular rotations of the “Cp*Rh(μ-SCH3)” moieties on the trigonal planes of the octahedral Mo centers. Line-shape analyses of variable-temperature 1H NMR spectra measured in C6D5Cl yield activation parameters of ΔH = +80.2 kJ mol−1, ΔS = +22.1 J K−1 mol−1, and ΔG298 K = +73.6 kJ mol−1 for the rotation in 2 and ΔH = +76.8 kJ mol−1, ΔS = +21.1 J K−1 mol−1, and ΔG298 K = +70.5 kJ mol−1 for that in 3.
  • Norihiko Yasuta, Sinjiro Takahashi, Nobuo Takenaka, Takeshi Takemura
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 1997-2003
    Published: 1999
    Released: December 10, 2004
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    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.
  • Masoumeh Hasani, Mojtaba Shamsipur
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2005-2010
    Published: 1999
    Released: December 10, 2004
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    Interactions of 1,4,7,10,13-pentaoxa-16-azacyclooctadecane (aza-18-crown-6) and 1,4,7-trioxa-10-azacyclododecane (aza-12-crown-4) with iodine have been investigated spectrophotometrically in chloroform and 1,2-dichloroethane solutions. The observed time dependence of the charge-transfer band and subsequent formation of I3 in solution were related to the slow transformation of the initially formed 1 : 1 macrocycle·I2 outer complex to an inner electron donor–acceptor (EDA) complex, followed by fast reaction of the inner complex with iodine to form a triiodide ion, as follows:

          

    The pseudo-first-order rate constants at various temperatures for the transformation process were evaluated from the absorbance-time data. The activation parameters (Ea, ΔH, and ΔS) for the transformation were obtained from the temperature dependence of the rate constants. The stoichiometry and formation constants of the resulting EDA complexes have also been determined. The influences of both the azacrowns’ structure and the solvent properties on the kinetics and stability of the resulting charge-transfer complexes are discussed.
  • Takehiko Mori
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2011-2027
    Published: 1999
    Released: December 10, 2004
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    δ-phase (β-PF6 type) BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene)-based organic conductors are characterized by the twisted overlap mode in the stack. Since the twisted mode has large intermolecular orbital overlap, the δ-phase is regarded as a twisted dimer structure. This type of overlap is, however, insensitive to small changes of the structure. On the contrary, an oblique interaction alters the warping of the open Fermi surface, to control the metal-insulator transition temperature, TMI. Through the change of this oblique interaction, TMI is scaled by the axis ratio for a family of salts with the same stacking pattern. As a general summary of BEDT-TTF salts, an empirical rule is proposed to predict, from the number of crystallographically independent molecules, whether an insulating state of BEDT-TTF salts will be paramagnetic or nonmagnetic. This rule is based on hypothetical pair formation of spins located on each dimer, and universally applies to all BEDT-TTF salts. This rule is extended to metallic salts, and among the potentially nonmagnetic salts, a dimerized dimer structure is the necessary condition of superconductivity. The potentially paramagnetic superconductors have strongly dimerized structures like β and κ phases. From this we can make a reasonable prediction as to superconducting phases.
  • Takahiro Ueda, Nobuo Nakamura, Masayasu Iida
    1999 Volume 72 Issue 9 Pages 2029-2031
    Published: 1999
    Released: December 10, 2004
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    The lineshape of 59Co NMR was measured on solid [Co(chxn)3]3+ (chxn = trans-(1R,2R)-1,2-diaminocyclohexane) at the Larmor frequencies of 47 and 96 MHz. The 59Co nuclear quadrupole coupling constant and the asymmetry parameter of the electric field gradient were determined to be 7.50 MHz and 0.75, respectively. These values correspond to a very small distortion of the complex cation in the crystal.
  • Takatoshi Seto
    1999 Volume 72 Issue 9 Pages 2033-2040
    Published: 1999
    Released: December 10, 2004
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    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.
  • Mandeep Singh Bakshi, Hidekazu Doe
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2041-2047
    Published: 1999
    Released: December 10, 2004
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    The conductances of hexadecylpyridinium chloride (HPyCl) + trimethyltetradecylammonium bromide (TTAB) mixtures over the entire mole fraction range of HPyCl (αHPyCl) were measured in aqueous binary mixtures of polyethylene glycol (PEG) 200, 400, 600, and 4000 containing different amounts of each PEG in their respective binary mixtures at 30 °C. Each conductivity curve showed a single break, except in the presence of PEG 4000 where two breaks were observed. From the conductivity (κ) data, the critical micellar concentration (cmc), degree of counter ion association (χ), the equivalent conductivities (Λ) from the slope of κ versus C plots, and the standard Gibb’s free energy of transfer of the surfactant hydrocarbon chain from the medium to the interior of the micelle (ΔGHP°) were computed. It was observed that micelle–PEG interactions in the case of HPyCl and TTAB were quite similar to mixed micelle–PEG interactions especially in the presence of PEG 200, 400, and 600. The results were explained on the basis of medium structure-breaking effects of PEG and adsorption of PEG on the micelle–solution interface. In the presence of PEG 4000, the micelle formation corresponding to the first break was found to be similar to that in the presence of PEG 200, 400, and 600. The second break was designated to the polymer bound micellar aggregates, which became more stable as the amount of PEG 4000 was increased.
  • Hiroshi Ono, Shin’ichi Ishimaru, Ryuichi Ikeda, Hiroyuki Ishida
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2049-2054
    Published: 1999
    Released: December 10, 2004
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    Measurements of 1H, 2H, 19F, 31P, and 35Cl NMR, differential scanning calorimetry (DSC), and X-ray powder diffraction were carried out in solid pyrrolidinium perchlorate ([C4H8NH2]ClO4) and hexafluorophosphate ([C4H8NH2]PF6). Five and three solid phases were obtained in perchlorate and hexafluorophosphate, respectively, by DSC measurement above 150 K. X-Ray powder patterns showed the highest-temperature solid phase of both salts to be CsCl-type cubic, indicating that both cations and anions take isotropically disordered orientations. The measurements of the NMR linewidth and its second moment revealed that the C4H8NH2+ and PF6 ions perform self-diffusion as well as isotropic rotation in this phase. From the dynamical behaviour of ions, the highest-temperature phase can be assigned to be an ionic plastic phase; this is the first example of an ionic plastic phase containing pyrrolidinium cations.
  • Yukio Yamamoto, Seiichi Tagawa
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2055-2060
    Published: 1999
    Released: December 10, 2004
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    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.
  • Tomonori Ida, Kazunaka Endo, Masahiko Suhara, Motoko Kenmotsu, Kenji H ...
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2061-2065
    Published: 1999
    Released: December 10, 2004
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    109Ag NMR signals in AgxCu1−xI crystals were shifted to a low field relative to that in solid AgI with decreasing the unit cell constant analogously to 63Cu MAS NMR signals reported in a previous study. The observed chemical shieldings were analysed using the results of Ag and Cu NMR shielding calculations of tetrahedral (Td) MI43− (M = Ag, Cu) complex ions with the ab initio GAUSSIAN 94 program using a double-ζ basis set for the Ag, Cu, and I atoms. Since the shift is explained dominantly by the paramagnetic shielding term, which depends on the d-hole and p-electron densities in Ag or Cu atoms for the MI43− complex ions, the observed 109Ag shift moved to a low field with decreasing the lattice constant, corresponding to an increase in the d-hole and p-electron densities for AgI43− (RAg–I = 2.68, 2.73, 2.77 Å) relative to the AgI43− (RAg–I = 2.81Å) ion.
  • Ikuo Tokue, Hiroyuki Tanaka, Katsuyoshi Yamasaki
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2067-2072
    Published: 1999
    Released: December 10, 2004
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    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.
  • Muhammad Ashfaq, Abdul Majeed, Abdul Rauf, Abdul Wahab Khan Khanzada, ...
    1999 Volume 72 Issue 9 Pages 2073-2078
    Published: 1999
    Released: December 10, 2004
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    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.
  • Mayumi Danjo, Aki Hayashi, Hirokazu Nakayama, Yumi Kimira, Tomoko Shim ...
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2079-2084
    Published: 1999
    Released: December 10, 2004
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    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.
  • Hajime Katano, Mitsugi Senda
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2085-2090
    Published: 1999
    Released: December 10, 2004
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    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.
  • Ok-Sang Jung, Young-A Lee, Sung Ho Park, Kyung Ho Yoo
    1999 Volume 72 Issue 9 Pages 2091-2096
    Published: 1999
    Released: December 10, 2004
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    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)].
  • Shuji Oishi, Noriyuki Michiba, Nobuo Ishizawa, Juan Carlos Rendon-Ange ...
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2097-2101
    Published: 1999
    Released: December 10, 2004
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    Large and well-formed crystals of barium chlorapatite [Ba5Cl(PO4)3] were grown for the first time from a sodium chloride flux. The solubility of Ba5Cl(PO4)3 in NaCl increased with increasing temperature, reaching about 1.9 mol% solubility at 1100 °C. The crystal growth of Ba5Cl(PO4)3 was conducted by heating a mixture of solute and flux at 1100 °C for 10 h, and then cooling to 500 °C at a rate of 5 °C h−1. Colorless and transparent prismatic crystals with lengths of up to 12 mm and widths of 3 mm were grown from high-temperature solutions containing 0.4—2.2 mol% solute. The most suitable solute content for the growth of prismatic crystals was 1.2 mol%. The prismatic crystals were bounded by the {} and {} faces. The aspect ratios were in the region of 1.1 to 4.8. Needle crystals with lengths of up to 4 mm and widths of 60 μm were obtained during every growth run. The needle crystals were elongated in the <0001> directions, with aspect ratios ranging from 43 to 56. The major constituents were almost homogeneously distributed in the prismatic and needle crystals.
  • Mitsunobu Nakamura, Masamichi Miki, Tetsuro Majima
    Type: Accounts
    Subject area: AI
    1999 Volume 72 Issue 9 Pages 2103-2109
    Published: 1999
    Released: December 10, 2004
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    9,10-Dicyanoanthracene (DCA) photosensitized intramolecular binaphthalene elimination of dinaphthyl methylphosphonates and trinaphthyl phosphates occurred through an exciplex between the singlet excited DCA (1DCA*) and the naphthyl group of dinaphthyl methylphosphonate and trinaphthyl phosphates in tetrahydrofuran, 1,4-dioxane, and benzene. Diethyl mononaphthyl phosphates also formed an exciplex with 1DCA*, while no reaction occurred. The binaphthalene elimination occurs via the intramolecular quenching of the exciplex by the second naphthyl group of dinaphthyl methylphosphonate or trinaphthyl phosphate, while the exciplex between the mononaphthyl phosphate and 1DCA* decays to give the starting compounds. The lifetime of the exciplex between the trinaphthyl phosphate and 1DCA* was shorter than that between the mononaphthyl phosphate and 1DCA*. The termolecular interaction (teraromatic groups interaction) of 1DCA* and two naphthyl groups of dinaphthyl methylphosphonate or trinaphthyl phosphate is suggested by the emission observation of the termolecular interaction of two naphthyl groups of trinaphthyl phosphate and 1,4-dicyanobenzene in the singlet excited state during the quenching of the intramolecular excimer of dinaphthyl methylphosphonate or trinaphthyl phosphates by 1,4-dicyanobenzene. The O–P(O)–O spacer is necessary for the binaphthalene elimination during the termolecular interaction in the singlet excited state.
  • Koji Yano, Susumu Matsuda, Keita Tani, Koji Yamamoto, Hiroshi Matsubar ...
    1999 Volume 72 Issue 9 Pages 2111-2114
    Published: 1999
    Released: December 10, 2004
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    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.
  • Masahiko Isaka, Paul G. Williard, Eiichi Nakamura
    1999 Volume 72 Issue 9 Pages 2115-2116
    Published: 1999
    Released: December 10, 2004
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    Reaction of a substituted allylsilane with N-chlorosulfonyl isocyanate at 0 °C takes place in an unexpected manner to give a [3 + 2] cycloaddition product, a β-silyl-γ-lactam, rather than a [2 + 2] cycloadduct.
  • Thirumalaiswamy Raja, T. M. Jyothi, K. Sreekumar, M. B. Talawar, J. Sa ...
    1999 Volume 72 Issue 9 Pages 2117-2119
    Published: 1999
    Released: December 10, 2004
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    The oxidation of various alcohols with a ketone was carried out over a series of calcined layered double hydroxides, producing corresponding ketones in a batch reaction system. From the observed results it was found that the layered double hydroxide, MgII–AlIII (4:1) ratio), calcined in air at 723 K efficiently oxidize alcohols compared with other LDHs.
  • Abdollah Salimi, Mir Fazlollah Mousavi, Hashem Sharghi, Mojtaba Shamsi ...
    1999 Volume 72 Issue 9 Pages 2121-2127
    Published: 1999
    Released: December 10, 2004
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    The preparation and electrochemical characterization of glassy carbon electrodes modified by four recently synthesized 1,4-dihydroxy-9,10-anthraquinone derivatives are reported. The anthraquinones used were strongly and irreversibly adsorbed on the preanodized glassy carbon electrodes. The electrochemical behavior and stability of the modified electrodes were studied by cyclic voltammetry at different acidic and basic aqueous solutions, and pH of 6—7 was chosen as the optimum working pH. The adsorbed anthraquinone derivatives showed excellent electrocatalytic ability for the reduction of O2 to H2O2 with overpotentials of from 560 to 650 mV lower than that of a plain glassy carbon electrode. The heterogeneous rate constants for the reduction of O2 at the surface of the modified electrodes were determined by rotating-disk electrode voltammetry using the Koutecky–Levich plots. The apparent diffusion coefficient of O2 in buffered aqueous O2-saturated solutions was also estimated.
  • Daiyo Terunuma, Tomonori Kato, Rei Nishio, Yoshio Aoki, Hiroyuki Nohir ...
    1999 Volume 72 Issue 9 Pages 2129-2134
    Published: 1999
    Released: December 10, 2004
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    A series of new carbosilane dendrimers carrying cyanobiphenyl derivatives was prepared starting from the tertiary core molecule, triallylphenylsilane. The phase transition of the dendrimers depends on the dendrimer generation, and the spacer lengths were investigated by using differential scanning calorimetry (DSC) and an optical polarizing microscope. All of the dendrimers prepared exhibited smectic A phases. The phase behavior on the phase-transition pattern of the DSC curve and the texture appearances of G2-mesogen(5) carrying twenty-seven mesogens were observed to be similar to that of the reported G2 dendrimer prepared starting from the quarternary core molecule, tetraallylsilane, carrying thirty-six mesogens.
  • Seiichi Inoue, Tomoko Ogi, Yoshi Yazaki
    1999 Volume 72 Issue 9 Pages 2135-2141
    Published: 1999
    Released: December 10, 2004
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    Radiata pine bark was treated with 0—15% hydrogen peroxide (H2O2) solutions at temperatures higher than 100 °C, and fractionated into water soluble, insoluble, and gas fractions. The distribution of these fractions was calculated on the basis of weight and carbon content, and compared with the aim of finding the optimum conditions for efficiently obtaining water-soluble materials for producing wood adhesives. The yield of water-soluble materials was significantly dependent on the temperature and the concentration of H2O2 solution. The highest yields of water-soluble materials (47.4 and 47.9% on the basis of weight and carbon content, respectively) were obtained with 15% H2O2 solution at 120 °C. The yield increased with increasing temperature up to 120 °C and then decreased at higher temperatures. Under the latter conditions, gases such as CO2 and CO were generated. When the bark was treated with 15% H2O2 solution at 140 °C, an exothermic reaction took place and 47.4% of the carbon of the bark was converted into gases. At the same time, most of the H2O2 was decomposed. The water-soluble fraction mainly consisted of low molecular weight acidic components, which are degaradated and oxygenated products of lignin and polyflavanoids. This bark solubilization process consists of very complicated combinations of various reactions. Many organic compounds, other than acids, might be present in the water-soluble fraction. The water-insoluble material is the oxygenated cellulose compound.
  • Mamoru Ai, Kyoji Ohdan
    1999 Volume 72 Issue 9 Pages 2143-2148
    Published: 1999
    Released: December 10, 2004
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    Various mixed oxides were tested as catalysts for oxidative dehydrogenation of hydroxyacetone to form pyruvaldehyde (2-oxopropanal). The best results were obtained from an iron phosphate with a P/Fe atomic ratio of 1.05. The yield of pyruvaldehyde reached 88%. The next best results were obtained from a supported heteropoly acid (H3PMo12O40). The other molybdenum- and vanadium-based oxide catalysts were not suitable. The effects of the composition and structure of iron phosphate and the effects of reaction variables on the formation of pyruvaldehyde were also studied.
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