Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 62 , Issue 6
Showing 1-50 articles out of 84 articles from the selected issue
  • Jun Nakauchi, Yoshitaka Kageyama, Seiji Hayashi, Keiichi Sakashita
    1989 Volume 62 Issue 6 Pages 1685-1691
    Published: 1989
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    The temperature dependence of the spontaneous polarization (Ps) and the optical tilt angle (θ) of the following series of novel ferroelectric liquid crystals, derived from normal alkyl esters of (R)-3-hydroxybutanoic acid, have been investigated.
    (Remark: Graphics omitted.)
    The magnitude of Ps and θ depends on the kind of linkage groups and their position in the core moiety as well as on the lengths of both terminal chains. The Ps’s for I(m,n) and II(m,n) show a maximum at (m,n)=(10, 3), whereas their θ’s increase with the m and do not change very much with n. In comparison with four analogues (I(10,3), II(10,3), III(10,3), and IV(10,3)), which have the same terminal chains, but which show a different phase sequence, the magnitudes of Ps and θ are in the orders of: III(10,3)>IV(10,3)>I(10,3)∼II(10,3) and III(10,3)>I(10,3)>II(10,3)>IV(10,3) respectively. Among all the compounds, the III(10,3) shows the maximum Ps as high as 1100 μCm−2 in the chiral smectic C phase and as high as 1750 μCm−2 in the chiral smectic I phase.
  • Etsuro Iwamoto, Shoji Yamasaki, Takahiro Kumamaru
    1989 Volume 62 Issue 6 Pages 1692-1697
    Published: 1989
    Released: June 27, 2006
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    The basicity of water in methanol (MeOH) and MeOH–1,2-dichloroethane (DCE) mixtures was examined by using spectral data of the title square planar chelate cation ([Ni(tmc)]2+). Although MeOH molecules are hardly coordinated to the chelate, the water molecules hydrogen-bonded with MeOH are easily coordinated to the cation, depending on the degree of hydrogen-bonded networks of MeOH. A fitting method showed that in the MeOH-rich mixtures the dimerization of water occured and only the terminal monomeric water molecule in the MeOH oligomer could be coordinated. The equilibrium constant KNiW1=[Ni(tmc)(H2O)2+]/[Ni(tmc)2+][H2O] was 3.2 in the 0.1 MeOH mole fraction mixture, 3.0 in 0.3, 3.2 in 0.5, 6.2 in 0.7, 9.5 in 0.9, 10.0 in 1.0. Linear relationships of 1H chemical shift of the OH group for MeOH in various solvents with the KNiW1 values and Gutmann’s donor number (DN) were found and DN values were estimated for the DCE–MeOH mixtures. The enhancement of basicity of the water molecules was discussed from the viewpoints of the charge transfer effect through hydrogen bonding and the development of hydrogen-bonded networks.
  • Hiroshi Yokoi, Akihide Kadowaki, Shuji Ikoma
    1989 Volume 62 Issue 6 Pages 1698-1700
    Published: 1989
    Released: June 27, 2006
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    Stable colloidal particles of reddish brown Cu2O–PVA and grayish black Cu–PVA composites have been prepared by the reduction of green Cu2+–PVA complexes in aqueous solutions with hydrazine, at the [hydrazine]/[Cu2+] ratios of 1–3 and 15 or more respectively, where PVA represents poly(vinyl alcohol). The average diameters of the Cu2O and Cu particles in these composites have been estimated to be about 200 and 300 Å respectively from the half widths of the X-ray diffraction peaks for the corresponding powder samples.
  • Tetsuro Majima, Tadahiro Ishii, Shigeyoshi Arai
    1989 Volume 62 Issue 6 Pages 1701-1709
    Published: 1989
    Released: June 27, 2006
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    The infrared multiple-photon decomposition (IRMPD) of saturated open-chain ethers has been systematically investigated with the intention of establishing their decomposition patterns. The main products in the IRMPD of ethers (1a–f, 2) are H2CO, CO, H2, and lower hydrocarbons. Acetaldehyde is additionally formed in the IRMPD of 1b and 1d, while acetone is formed in the IRMPD of 1d. The observed results are explained on the basis of the decomposition of the highly vibrationally excited ethers produced in the IRMP excitation. The initial process is the homolytic cleavage of a C–O bond to yield the corresponding alkyl and alkoxyl radicals. The alkyl radicals are trapped by Br2. Sequential splitting and addition reactions of the radicals yield primary products with a high internal energy. The primary products also decompose sequentially into stable products, in part. The sequential processes compete with collisional deactivation. Therefore, the branching ratio depends on the internal energy of the radicals and the primary products.
  • Tetsuro Hanawa, Hiroshi Yoneyama
    1989 Volume 62 Issue 6 Pages 1710-1714
    Published: 1989
    Released: June 27, 2006
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    Electropolymerized polypyrrole films exhibited noticeable gas sensitivities to electron acceptor gases such as PCl3, SO2, and NO2 at room temperature only when they were reduced electrochemically, and the resistance decrease was larger with the gas of larger electron affinity. It was also found that the resistance decrease obeyed the Elovich equation in an early stage of the gas exposure.
  • Koichi Nozaki, Akira Naito, Hiroyuki Hatano, Satoshi Okazaki
    1989 Volume 62 Issue 6 Pages 1715-1724
    Published: 1989
    Released: June 27, 2006
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    Numerical decoupling analysis (NDA) has been developed as a useful analytical method for determining accurate hyperfine coupling constants (hfccs) involved in isotropic ESR spectra with constant line-widths. NDA was found to have a number of advantages over other methods developed for the extraction of hfccs from ESR spectra. For example, the nuclear spin (e.g., I=1⁄2 or 1) can easily be distinguished and hfccs as small as a linewidth can be determined. Furthermore, false hfccs which often appear and lead to confusion in obtaining the true values in other methods are largely eliminated. Owing to these advantages NDA has enabled us to interpret not only complex but also poorly resolved ESR spectra. The practical use of NDA could be demonstrated by analyzing the ESR spectra of t-butyl 4-nitrophenyl nitroxide and t-butyl 2-chlorophenyl nitroxide radicals.
  • Noriaki Funasaki, Sakae Hada, Saburo Neya
    1989 Volume 62 Issue 6 Pages 1725-1730
    Published: 1989
    Released: June 27, 2006
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    The aggregation properties of Triton X-100 are investigated by frontal gel (Sephadex G-200) filtration chromatography (GFC) at 25 °C and considered in the framework of the monomer–m-mer equilibrium on the basis of both asymptotic and plate theories. The analysis of GFC data by asymptotic theory yields an equilibrium constant of K=1.3×1068 (mmol dm−3)−138 and a micellar elution volume of Vm=15.30 cm3. By using this Vm value, we calculate a micellar hydrodynamic radius of 4.6 nm and the monomer concentration C1 for Triton X-100. Values of cmc=0.30 mmol dm−3 (UV at 245 nm) and 0.31 mmol dm−3 (UV at 265 nm and GFC) are determined and are very close to the cmc value theoretically calculated by using Phillips’ definition of the cmc. The C1 value above the cmc is larger than these cmc values by about 0.06 mmol dm−3. The derivative elution pattern at the trailing boundary exhibits two maxima and a minimum (Vmin), and indicates the formation of small micelles near the cmc. The concentration at Vmin on the elution curve, Cmin, is close to the cmc, as we have already predicted by both asymptotic and plate theories. The present work demonstrates the utility of these theories for analyzing the GFC pattern of self-associating systems and will serve to understand the actions of Triton X-100 on membrane bound proteins and on lipid bilayers.
  • Kwan Young Lee, Noritaka Mizuno, Toshio Okuhara, Makoto Misono
    1989 Volume 62 Issue 6 Pages 1731-1739
    Published: 1989
    Released: June 27, 2006
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    Ethanol, diethyl ether, and water absorbed in, and their thermal desorption from, the pseudoliquid phase of 12-tungstophosphoric acid have been studied by means of infrared spectroscopy. For all three molecules, the state of the absorption of 6 molecules per anion, H3PW12O40·6R2O (R; C2H5 or H), was quite stable and the secondary structures were similar. The intensities of the C–H vibrations indicated that the methyl group of the ethanol molecules interacted with the anions and that its interaction became stronger as the amount of absorbed molecules decreased. In the thermal desorption of absorbed ethanol or diethyl ether, a protonated monomer and dimer as well as an ethoxy group were detected by means of infrared spectroscopy. These species are reaction intermediates of the dehydration of ethanol which were assumed previously (J. Am. Chem. Soc., 109, 5535 (1987)). It was also found that, upon the dehydration of H3PW12O40·6H2O, the proton which had been hydrogen-bonded to the oxygen atom of the water molecule ((H2O)2H+) migrated onto the bridging oxygen of the heteropoly anion (PW12O4O403−).
  • Zheng-Zhong Lin, Toshiyuki Enomoto, Toshio Okuhara, Makoto Misono
    1989 Volume 62 Issue 6 Pages 1740-1744
    Published: 1989
    Released: June 27, 2006
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    The effects of the addition of alkalis to a Ru/SiO2 catalyst upon the conversion (hydrogenolysis and dehydrogenation) of cyclohexane, hydrogenolysis of butane, and hydrogenations of benzene and CO were studied. The addition of K or Cs slightly enhanced the catalytic activity for the hydrogenolysis of cyclohexane, whereas dehydrogenation to benzene was markedly suppressed. This result is contrary to the effect of the addition of Cu or Au to group-VIII metals, as reported in the literature. Changes in the activities became less significant as the atomic number of the added alkali decreased. From a systematic examination by varying the alkali content, it was revealed that dehydrogenation and CO hydrogenation were very sensitively suppressed by an electronic effect imposed by the alkalis, whereas changes in the activities of hydrogenolysis and benzene hydrogenation were not great.
  • Toshihiro Tominaga, Toru Maruyama, Takayuki Koshiba, Yuroku Yamamoto
    1989 Volume 62 Issue 6 Pages 1745-1750
    Published: 1989
    Released: June 27, 2006
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    Tracer diffusion coefficients for the [Fe(phen)3]2+ cation (phen=1,10-phenanthroline) have been measured in aqueous solutions of sodium 1-hexane-, 1-octane-, 1-decane-, and 1-dodecanesulfonate (NaDSO) in concentration ranges below the critical micelle concentrations of the surfactants and at 298.2 K. The diffusion coefficient decreases with an increase in the concentration of the surfactants. At a fixed concentration, the diffusion coefficient decreases with an increase in the carbon number of the surfactants. The results are compared with our previous results in sodium dodecyl sulfate (NaDS) solutions. The conductivities of the NaDSO and NaDS solutions were also measured at 298.2 K in the presence and absence of [Fe(phen)3]SO4. In the presence of [Fe(phen)3]SO4, the molar conductivities of the surfactants first decrease, then increase, and finally decrease again with an increase in the concentration of the surfactants.
  • Kayako Hori, Miho Takamatsu, Yuji Ohashi
    1989 Volume 62 Issue 6 Pages 1751-1757
    Published: 1989
    Released: June 27, 2006
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    Interlayer distances of Sm*C and Sm A phases of the title series were measured as functions of temperature by X-ray diffraction. With increase in temperature, molecular tilt angles in Sm*C decrease from 22–25 to 0°. Crystal structures of the heptyl (1) and octyl (2) homologues have been determined by X-ray analysis. (1): 4-[(S)-2-Methylbutyl]phenyl 4′-heptyloxybiphenyl-4-carboxylate, monoclinic, P21, a=26.929(4), b=5.4249(5), c=9.2607(9) Å, β=96.78(1)°, Z=2. (2): 4-[(S)-2-Methylbutyl]phenyl 4′-octyloxybiphenyl-4-carboxylate, orthorhombic, P212121, a=9.249(1), b=56.259(9), c=5.412(1) Å, Z=4. Final R were 0.076 and 0.121, respectively. Both crystals have distinct layer structures similar to those of Sm*C. In the former crystal, the molecules tilt to one direction uniformly throughout layers, while in the latter, they take two opposite directions alternately from layer to layer. However, structures within a layer are very similar to each other. Each molecule has a coplanar biphenyl moiety and a twisted paraffin chain. Mesophase behavior was interpreted very well by the molecular interaction revealed in the crystal structures.
  • Naoki Satoh, Keisaku Kimura
    1989 Volume 62 Issue 6 Pages 1758-1763
    Published: 1989
    Released: June 27, 2006
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    Metal fine particles are not dispersed at all in pure solvents with a low dielectric constant, such as hexane. The gas flow-cold trap method combined with surfactants was found to be effective in stabilizing ultrafine metal particles in solvents with a low dielectric constant. Ultrafine gold particles can be stably dispersed in hexane in a colloidal state by this method. It was found that the stabilizability of the colloid depends on the ionic types of the surfactant. Thus, a cationic surfactant such as dimethyldioctadecylammonium chloride (DOAC) shows good dispersibility, whereas an anionic surfactant such as 1,2-bis(2-ethylhexyloxycarbonyl)ethanesulfonate (AOT) dose not. The optical spectra of colloid solutions suggest a difference in the local colloidal state between two types of surfactants. Colloidal solutions of a gold fine particle/DOAC/hexane system are so stable against heating or drying that the solvents are easily substituted.
  • Hiroshi Yoneyama, Yoshihiro Shoji, Kei-ichi Suzuki
    1989 Volume 62 Issue 6 Pages 1764-1770
    Published: 1989
    Released: June 27, 2006
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    A variety of surface conditions of n-type Si wafers were prepared by etching for different time damaged surfaces that were prepared by lapping with emery papers, and the effect of flaws in the wafer surfaces on photocatalytic deposition behaviors of polypyrrole and silver from acetonitrile containing pyrrole and AgClO4 was investigated. It was found that if the front surface of the wafer to be illuminated contained a fairly high amount of defects and the back surface in the dark was defect-free, oxidative polymerization of pyrrole occurred on the back surface in the dark with the simultaneous deposition of silver on the front surface as long as the diffusion length of positive holes is greater than the thickness of Si wafers.
  • Yasuhiko Yamamoto, Norishige Nanai, Yoshio Inoue, Riichirô Ch&uc ...
    1989 Volume 62 Issue 6 Pages 1771-1776
    Published: 1989
    Released: June 27, 2006
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    The metal-centered pseudo-contact shift contribution in the hyperfine shift of NMR resonance of paramagnetic hemin dicyano complex ([FeIII(proto)(CN)2]) in solution was quantitatively determined from the combined use of 1H and 13C NMR data. Taking advantage of the axially symmetric magnetic property for [FeIII(proto)(CN)2] in solution, the paramagnetic metal-centered dipolar field was quantitatively mapped. The highly solvent-dependent magnetic anisotropy, (g2⁄⁄g2), of this complex in CD3OD was estimated to be 7.2 and the obtained value is placed between the values in D2O (4.4) and in CDCl3 (9.7).
  • Norio Nishimura, Jun’ichi Miyake, Yoshimi Sueishi
    1989 Volume 62 Issue 6 Pages 1777-1780
    Published: 1989
    Released: June 27, 2006
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    The rates of thermal isomerization of 1′,3′,3′-trimethyl-8-nitrospiro[2H-1-benzopyran-2,2′-indoline]-6-carboxylic acid (6-COOH-8-NO2-SP) from its spiro form (SP) to its merocyanine form (MC) have been measured in some solvents and at high pressures. The equilibrium constants between these isomers at atmospheric pressure and at 30 °C are in the range of 0.25 to 2.52 depending on solvents. The activation volumes are 0.2–3.4 cm3 mol−1, while the reaction volumes are −7.9–−22.3 cm3 mol−1. Thus the volume profile was found to have a maximum, as predicted previously.
  • Hiromitu Hirakawa, Hiroyasu Nomura, Fumio Kawaizumi
    1989 Volume 62 Issue 6 Pages 1781-1784
    Published: 1989
    Released: June 27, 2006
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    Sedimentation potential (SP) measurements were carried out for solutions of alkali halides dissolved in methanol. With the SP data thus obtained, the partial molar volumes V2 of alkali halide MX, V2 (MX), were divided into cationic V2 (M+) and anionic V2 (X) parts. The ionic partial molar volumes evaluated showed a reasonable agreement with each other. These values of V2 (M+) and V2 (X) are numerically compatible with those reported earlier by Kawaizumi and Zana using the ultrasonic vibration potential method and those given more recently by French and Criss based on the apportionment of the estimated V2 value for the large complex [Ph4PBPh4] (J. Solution Chem., 11, 625 (1982).) The magnitude of the concentration dependence of SP was evaluated theoretically by expressing the apparent molar volume, the transport number, and the density of a solution as functions of the solute concentration.
  • Nobuyuki Matsushita, Norimichi Kojima, Toshiro Ban, Ikuji Tsujikawa
    1989 Volume 62 Issue 6 Pages 1785-1790
    Published: 1989
    Released: June 27, 2006
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    Syntheses and optical properties of some new halogen-bridged mixed-valence platinum complexes analogous to Wolffram’s Red Salt, [Pt(en)2][PtBr2(en)2](HSO4)4 (PBHS), [Pt(en)2][PtI2(en)2](HSO4)4·4H2O (PIHS), and [Pt(en)2][PtX2](en)2](SO4)2·6H2O {X=Br(PBSW), I(PISW)}, are reported. The powder X-ray diffraction pattern shows that PBHS is isomorphous with [Pt(en)2][PtCl2(en)2](HSO4)4 (PCHS), and that PBSW and PISW are isomorphous. The hydrogensulfates PBHS and PIHS crystallize from an aqueous sulfuric acid solution, whereas the sulfates PBSW and PISW crystallize from an aqueous solution. The single crystal absorption spectra of PBHS, PIHS, PBSW, and PISW have been investigated at 4.2 K. The intense optical absorption due to intervalence charge-transfer transition from Pt(II) to Pt(IV) has been observed for the light polarized parallel to the Pt chain axis (E//chain). From the comparison of the energy of the intervalence charge-transfer absorption edges in PBHS, PBSW, and PISW, one can conclude that the influence of the substitution of the counterions HSO4 with SO42− on the Pt(II)–Pt(IV) mixed-valence state is no less better than that of the substitution of the bridging halogen. The role of the counterion on the mixed-valence state is explained by the hydrogen bond network (Pt–NH···counterion···HN–Pt) on individual chains.
  • Takafumi Miyanaga, Takashi Fujikawa, Nobuyuki Matsubayashi, Takao Fuku ...
    1989 Volume 62 Issue 6 Pages 1791-1796
    Published: 1989
    Released: June 27, 2006
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    EXAFS (Extended X-ray Absorption Fine Structure) experiments on various polynuclear molybdate and tungstate compounds revealed the unusual phenomenon that Mo–O peaks which should appear at around 1.9 Å in Fourier transforms of the EXAFS spectra for Mo6O192− and PMo12O403− are hardly discernible, while the tungstates and other molybdates give the metal–oxygen peaks normally. It is concluded that the Debye–Waller factors for the metal-bridging oxygen bonds in Mo6O192− and PMo12O403− are exceptionally large (≥0.08 Å). The shape of the Raman bands for the Mo6O192− pertaining to the vibration involving the bridging oxygens supports the large σ values estimated. EXAFS measurements were also performed for AsMo12O403−, SiMo12O404−, and PMo12O403−. The compounds with large Debye–Waller factors seem to be unstable against reductants.
  • Motoho Muroi, Teruo Kamiki, Eiichi Sekido
    1989 Volume 62 Issue 6 Pages 1797-1801
    Published: 1989
    Released: June 27, 2006
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    Ortho-, meta-, and paracyclophane-type thiacrown compounds bearing 4-(4-nitrophenylazo)phenol as a chromogenic group were synthesized, and their characteristics as extractive-spectrophotometric reagents for the class b metals, consisting of soft Lewis acids such as silver and copper(I), were examined. Silver and copper(I) were well extracted into chloroform with all of three reagents, though especially with the metacyclophane-type reagent. The absorption maxima of silver and copper(I) complexes with the orthocyclophane-type reagents are at the longest wavelengths among the three reagents. The orthocyclophane-type reagent is adequate for the extraction and spectrophotometric measurement of copper(I), and the metacyclophane-type reagent is suitable for that of silver. The extraction behavior of copper(II) with these three reagents has been studied in order to know if the hydroxyl group participates in the formation of the metal–thiacrown complexes.
  • Kiyoshi Isobe, Yukio Nakamura, Shinichi Kawaguchi
    1989 Volume 62 Issue 6 Pages 1802-1808
    Published: 1989
    Released: June 27, 2006
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    The oxidative addition of 2-(chloromethyl)pyridine to tetrakis(triphenylphosphine)palladium(0) in toluene at 100 °C gave [{PdCl(C5H4N-2-CH2)PPh3}2] (1a), which was characterized by analytical, molecular-weight, and IR data as well as 1H, 31P, and 13C NMR spectroscopy. The chloride ligand was readily replaced by other halides, whereas tertiary phosphines such as diphenylmethyl-, phenyldimethyl-, and triethylphosphines cleaved the bridge after substitution of triphenylphosphine to result in the monomeric trans-[PdCl(C5H4N-2-CH2)(PR3)2] complexes. Reactions of 1a with carbon monoxide and other reagents are also reported. The corresponding 3-picolyl complex [{PdCl(C5H4N-3-CH2)PPh3}n] was also prepared, but could not be well characterized because of lower stability and solubility.
  • Fumiko Matsumoto, Naomi Matsumura, Akira Ouchi
    1989 Volume 62 Issue 6 Pages 1809-1816
    Published: 1989
    Released: June 27, 2006
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    The title complexes were synthesized and their crystal and molecular structures were determined by the X-ray diffraction method using their single crystals. The crystals of the former ten hexakis(isothiocyanato) complexes of lanthanum through dysprosium(III) and erbiun(III) are isomorphous with each other: monoclinic, space group P21, Z=2. The central metal atom is octa-coordinated, in a square-antiprism geometry, to six nitrogen atoms of thiocyanato (SCN) ions and two oxygen atoms of methanol and water molecules. The two oxygen atoms take the positions of the most approaching apexes of two squares. The latter three heptakis(isothiocyanato) complexes of dysprosium, erbium, and ytterbium are in another isomorphous form with each other: orthorhombic, space group P21nb, Z=4. The central metal atom is hepta-coordinated, in a deformed pentagonal-bipyramidal geometry, to seven nitrogen atoms of SCN ions.
  • Hajime Ishii, Shinji Numao, Tsugikatsu Odashima
    1989 Volume 62 Issue 6 Pages 1817-1821
    Published: 1989
    Released: June 27, 2006
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    Extraction behavior of indium has been investigated with 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HMPP) at 25±0.1 °C and an ionic strength of 0.2. The values of the proton-dissociation constants, pKa1 and pKa2, of HMPP were determined spectrophotometrically to be 3.02 and 9.56. The value of the partition coefficient, logKD, of HMPP between 1,2-dichloroethane and water was determined to be 1.35. Indium(III) was extracted into 1,2-dichloroethane by forming a 1 : 3 (metal : ligand) complex with HMPP. The extraction constant, Kex, the overall formation constant, β3, and the distribution constant, KDC, of the indium(III)–HMPP complex were determined, their values being as follows: logKex=2.16, logβ3=32.63, and logKDC=2.26.
  • Naomi Hoshino, Yutaka Fukuda, Kozo Sone, Kiyoaki Tanaka, Fumiyuki Maru ...
    1989 Volume 62 Issue 6 Pages 1822-1828
    Published: 1989
    Released: June 27, 2006
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    A thermochromic copper(II) complex of 1,5-diazacyclooctane (daco), [Cu(daco)2](NO3)2, has been subjected to single-crystal X-ray and optical studies. This complex is orange as isolated, but it turns violet discontinuously when heated above 90 °C and returns to orange on cooling. Crystal structure of the low-temperature form has been determined at room temperature; the complex crystallizes in the monoclinic space group P21n with a=7.9040(7), b=15.694(1), c=7.0886(7) Å, β=95.36(1)°; V=875.5(1) Å3, and Z=2. The CuN4 chelate plane is planar and Cu–N coordination bonds are rather short. The structure has revealed the presence of weak hydrogen bonds bridging imino groups of the ligands with the nitrate ions and forming a macrocycle-like ring system, which results in enhancement of the ligand field strength. Single-crystal visible and infrared spectra for both low- and high-temperature forms have heen obtained and compared. A high-energy d–d transition band(s) causing the orange color at room temperature is in contrast to an extremely flattened broad band(s) for the violet form. The IR spectra of the two forms clearly differ in the intensity of νNH stretching peak, implying that the thermochromic phase transition involves a change in the nature of the hydrogen bonds of the imine ligands. On the basis of these observations and comparison to reported studies on a similarly thermochromic copper(II) complex, a mechanism is suggested involving dynamic fluctuation of the ligand field and geometry due to thermal motion of the anion/ligand hydrogen bond system.
  • Morihide Higo, Sinichi Mizutaru, Satsuo Kamata
    1989 Volume 62 Issue 6 Pages 1829-1836
    Published: 1989
    Released: June 27, 2006
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    The vibrational spectra of phthalic, isophthalic, and terephthalic acid adsorbed onto alumina and magnesia surfaces from the gas phase have been measured by inelastic electron tunneling spectroscopy. The analysis of the tunneling spectra shows that phthalic and isophthalic acid react with the surface OH groups on Al2O3 and MgO to give the adsorbed dicarboxylate ions on both surfaces. Phthalic acid is adsorbed with its benzene ring perpendicular to the surfaces, while isophthalic acid is adsorbed parallel to the surfaces. However, terephthalic acid is adsorbed predominantly as the monocarboxylate ion almost perpendicular to the alumina surface, while it is adsorbed as the dicarboxylate ion parallel to the magnesia surface. These results suggest the different properties of the surface OH groups on Al2O3 and MgO. There are more than one type of OH group on the alumina surface and they interact with each other through hydrogen bonding. The magnesia surface has an isolated and a hydrogen-bonding OH group. The OH groups on MgO are more basic than those on Al2O3, and thus have higher reactivity. The different properties and basicity of the OH groups cause the different orientation and reactivity of the adsorbed terephthalic acid on the alumina and magnesia surfaces.
  • Hiromichi Yamazaki, Yasuhito Kanno, Yasushi Inoue
    1989 Volume 62 Issue 6 Pages 1837-1843
    Published: 1989
    Released: June 27, 2006
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    Hydrous silicon(IV)–titanium(IV) oxide ion exchanger was prepared by using TiCl4 and Na2SiCO3 solutions. From a detailed examination of the dependency of the compositions and the acid–base properties of the products on the conditions for precipitation, a reproducible synthetic procedure was established. The exchangers with 37 to 67 mol% of titanium to metallic elements possess much larger ion-exchange capacities and are more stable to highly alkaline solutions than simple mixtures of hydrous silicon(IV) oxide and hydrous titanium(IV) oxide. The dependency of the ion-exchange capacity on the composition can be explained by the difference in the structure of the matrix as evidenced from the thermal analysis, X-ray diffraction, and infrared absorption studies.
  • Takao Ogawa, Seiji Yamada, Takeshi Miki, Hideyasu Tsuiki, Noriyoshi Ka ...
    1989 Volume 62 Issue 6 Pages 1844-1851
    Published: 1989
    Released: June 27, 2006
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    Superconductive films composed of Ba2YCu3O7−δ were prepared by fume pyrolysis with a temperature programmed electric furnace. Fumes generated from an aqueous solution of Ba, Y, and Cu nitrates with an aid of supersonicant were introduced into the furnace with flowing O2. Fine particles consisting of Ba, Y, and Cu ions were formed in the furnace and deposited on the surface of a YSZ substrate placed at the top of the furnace. Films thus prepared and annealed at 1273 K showed superconductive properties below 90 K and zero resistivity was observed at 80 K with 100 μA of the current.
  • Masao Ishii, Shigenobu Funahashi, Koji Ishihara, Motoharu Tanaka
    1989 Volume 62 Issue 6 Pages 1852-1858
    Published: 1989
    Released: June 27, 2006
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    The activation parameters for the exchange reaction of several nitriles at the nickel(II) ion have been determined for the nickel(II) trifluoromethanesulfonate solutions by means of the 14N NMR line broadening method at various temperatures and pressures up to 220 MPa. Values of activation enthalpy (ΔH\ eweq/kJ mol−1), activation entropy (ΔS\ eweq/J mol−1 K−1), and activation volume at zero pressure (ΔV0\ eweq/cm3 mol−1) for the exchange of various nitriles are respectively as follows: 41.4±0.5, −30±2, and +12.0±0.4 in acetonitrile; 42.0±0.4, −25±2, and +13.7±0.5 in propionitrile; 43.3±0.7, −23±2, and +13.1±0.5 in butyronitrile; 43.3±0.5, −19±2, and +12.4±0.6 in isobutyronitrile; 47.1±1.2, −10±4, and +14.4±0.4 in valeronitrile; 51.6±1.9, +4±6, and +13.1±0.6 in benzonitrile. The activation volume varies little in spite of the large variation of the molar volume of nitriles. The activation energy (EQ/kJ mol−1) and the activation volume at zero pressure (ΔVq\ eweq cm3 mol−1) for the reorientation of nitrile molecules around the axis perpendicular to the C≡N bond were also determined to be respectively as follows: 7.4±0.1 and +8.3±0.4 for acetonitrile; 8.1±0.1 and +9.5±0.2 for propionitrile; 9.2±0.1 and +9.7±0.3 for butyronitrile; 9.1±0.1 and +11.3±0.2 for isobutyronitrile; 10.7±0.2 and +11.9±0.2 for valeronitrile; 12.5±0.2, and +13.5±0.2 for benzonitrile. Both EQ and ΔVq\ eweq increase with increasing bulkiness of the substituent to the cyano group.
  • Songping Wan, Wasuke Mori, Shoichiro Yamada, Shun-Ichi Murahashi
    1989 Volume 62 Issue 6 Pages 1859-1863
    Published: 1989
    Released: June 27, 2006
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    Three types of imino oxime copper(II) complexes were obtained by the reactions of copper(II) perchlorate with imino oximes (3-[2-[(alkylamino)ethyl]imino]-2-butanone oximes or 3-[2-[(dialkylamino)ethyl]imino]-2-butanone oximes, abbreviated as Hdox-enRR′). One type contains the dinuclear complexes [Cu2(dox-enRR′)2]2+ and uncoordinated perchlorate anions. The magnetic susceptibilities measured over the temperature range 77–320 K indicate that there exists a strong antiferromagnetic spin coupling interaction through the N–O bridge in these complexes. The magnetic behavior can be explained by using the Bleaney–Bowers equation. Complexes of the second type probably contain a square-tetranuclear complex. The copper(II) ions assume a penta-coordinated configuration with perchlorate anion coordinated at the axial coordination site. It is assumed that the dinuclear and mononuclear magnetic units coexist in the complexes of the third type. The plot of the magnetic susceptibilities versus temperature is linear in the two temperature ranges (T>250 K, <100 K).
  • Yoshihito Ikariyama, Naoki Shimada, Tomoaki Yukiashi, Masuo Aizawa, Sh ...
    1989 Volume 62 Issue 6 Pages 1864-1868
    Published: 1989
    Released: June 27, 2006
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    A microbiosensing device fabricated by assembling an enzyme-embodied microelectrode with a counter electrode and a reference electrode was applied to the real time determination of trace droplet of glucose sample. The microdevice demonstrated unique properties such as real time response, independence of sample volume, unnecessity of sample mixing by the rendezvous of microfabricated biosensing device with pulse voltammetry. A linear relationship between sensor output and glucose concentration was obtained in the concentration range from 10−3 to 10−1 mol L−1. The sensing device responded to every glucose sample of different concentration in 2 ms, and the coefficient of variation for 10 mM glucose determination was within 5%.
  • Yoshihito Ikariyama, Shigeru Yamauchi, Tomoaki Yukiashi, Hiroo Ushioda ...
    1989 Volume 62 Issue 6 Pages 1869-1874
    Published: 1989
    Released: June 27, 2006
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    The advantages of miniaturized enzyme electrode have been applied to flow injection analysis for the development of a rapid and selective method for the continuous determination of glucose. By assembling a micro-enzyme electrode having a diameter of 10 μm for an amperometric flow-through detector, at least 600 glucose samples can be determined in one hour. And micro-enzyme electrodes are satisfactorily stable for over 4 weeks even after 1000 glucose injections.
  • Kazuhiko Ozutsumi, Toshiyuki Takamuku, Shin-ichi Ishiguro, Hitoshi Oht ...
    1989 Volume 62 Issue 6 Pages 1875-1879
    Published: 1989
    Released: June 27, 2006
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    The structure of solvated cadmium(II) ion and the tetrathiocyanatocadmate(II) complex in N,N-dimethylformamide (DMF) has been determined by means of X-ray diffraction at 25 °C. The radial distribution curve for a cadmium(II) perchlorate DMF solution is well explained in terms of the presence of the octahedral [Cd(dmf)6]2+ complex with the Cd–O bond length of 229.6(4) pm, which is practically the same as that within [Cd(dmso)6]2+ in DMSO and [Cd(H2O)6]2+ in H2O. It is also found that the tetrathiocyanatocadmate(II) complex has a tetrahedral structure, [Cd(NCS)3(SCN)]2−, with three Cd–N and one Cd–S bonds, the distances being 223(2) and 257(2) pm, respectively. The coordination structure of the complex in DMF is different from that found in aqueous solution, [Cd(NCS)2(SCN)2]2−.
  • Mareyuki Takahashi, Jyunichi Tsuchiya, Etsuo Niki
    1989 Volume 62 Issue 6 Pages 1880-1884
    Published: 1989
    Released: June 27, 2006
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    The inhibition of oxidation of methyl linoleate in homogeneous solution and in aqueous dispersions by diarylamines has been studied. Diphenylamines with electron-donating substituents exhibited antioxidant activities, while those having electron-withdrawing substituents such as niflumic acid and flufenamic acid did not suppress the oxidation appreciably. When both 4,4′-dimethoxydiphenylamine and α-tocopherol were present as antioxidants, only α-tocopherol was consumed at first and when α-tocopherol was almost completely depleted, 4,4′-dimethoxydiphenylamine began to be consumed to give nitroxide radical, which further acted as antioxidant.
  • Mareyuki Takahashi, Yasuyuki Yoshikawa, Etsuo Niki
    1989 Volume 62 Issue 6 Pages 1885-1890
    Published: 1989
    Released: June 27, 2006
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    Tocopherols suppressed the spontaneous, thermal oxidation of methyl linoleate and produced a clear induction period. During the induction period, small amounts of cis,trans-hydroperoxides were formed but the formation of trans,trans-hydroperoxides was almost completely inhibited. Tocopherols were consumed and when they were depleted, the induction period was over and a fast oxidation proceeded to give more trans,trans-hydroperoxides than cis,trans-hydroperoxides. However, tocopherols, especially α-tocopherol, acted as prooxidants when their concentrations were extraordinarily high and the rate of initial radical formation was low. The reducing agent such as ascorbic acid diminished the prooxidant action of α-tocopherol. This prooxidant effect of tocopherols was ascribed to the spontaneous formation of tocopheroxyl radical followed by the hydrogen atom abstraction by the tocopheroxyl radical from the hydroperoxide to give a peroxyl radical.
  • Toshiaki Yoshimura, Eiichi Tsukurimichi, Yukihiko Iizuka, Hironobu Miz ...
    1989 Volume 62 Issue 6 Pages 1891-1899
    Published: 1989
    Released: June 27, 2006
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    Substituted (RS,SR)-1-phenylethyl phenyl sulfoxides (threo) (XC6H4S(O)CH(CH3)C6H4Y) and some substituted (RR,SS)-sulfoxides (erythro) were prepared and kinetic investigation for the thermal decomposition was carried out at 80.0, 90.0, and 100.0 °C in dioxane. Hammett plots for threo-XC6H4S(O)CH(CH3)C6H5 gave positive ρ-values (ρX=0.60–0.64 at three temperatures), while those for threo- and erythro-C6H5S(O)CH(CH3)C6H4Y snowed V-shape lines with bottoms at the m-OCH3 substituent though the effects of the substituents are small. Meanwhile, large kinetic isotope effects for threo- and erythro-C6H5S(O)CH(CD3)C6H4Y (Y=H, p-OMe, m-Cl) (kHkD=4–6) were observed at all temperatures. The activation energies were in the range of 104–121 kJ mol−1 for all sulfoxides, while the activation entropies were relatively large (7–37 J K−1 mol−1) and were correlated with Hammett σ-values to give small negative trend. Reactions of all erythro-isomers examined were 2–3 times faster than those of the corresponding threo-isomers. From these results, it is suggested that the pyrolysis of 1-arylethyl aryl sulfoxides proceeds via a concerted mechanism in which the transition state is variable from an El-like to a conjugated one. In the latter transition state, conjugation of the phenyl group bearing the electron-withdrawing substituent with the developing π-bond electron acidifies the β-proton.
  • Chikao Hashimoto, Ichiro Muramatsu
    1989 Volume 62 Issue 6 Pages 1900-1907
    Published: 1989
    Released: June 27, 2006
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    A protected sperm whale myoglobin-(77–96)-eicosapeptide (23) was synthesized by a solution method. The protected peptide 23 could be effectively purified by silica-gel column chromatography with 1-butanol–acetic acid–water as the eluate. The CD spectra of protected fragment peptides were measured in a solution of 2,2,2-trifluoroethanol. A protected sperm whale myoglobin-(85–96)-dodecapeptide and 23 showed CD profiles characteristic of a helical structure.
  • Susumu Tanaka, Kyoji Kaeriyama
    1989 Volume 62 Issue 6 Pages 1908-1912
    Published: 1989
    Released: June 27, 2006
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    Soluble and conductive poly(3-methoxy-2,5-thiophenediyl) was obtained by the chemical oxidation of 3-methoxythiophene with iron(III) chloride. The resulting polymer was found to be in a doped state, since it contained 0.1–0.2 counterions (FeCl4 and Cl) per monomeric unit. This means that the oxidation is a convenient method for preparing conductive polymers in one step. We also obtained a poly-MOT solution and film in a state doped to a great extent, showing no π–π* transition band and a high stability in air. An undoped polymer film was prepared by the electrochemical reduction of the doped film. The undoped film had a π–π* transition band at 2.3 eV, indicating that the effective conjugation length of the polymer could be assumed to be the same as that of the poly(3-methoxythiophene) prepared electrochemically.
  • Yukio Iino, Eijiro Hara, Makoto Nitta
    1989 Volume 62 Issue 6 Pages 1913-1916
    Published: 1989
    Released: June 27, 2006
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    The first syntheses of N-(2,4,6-cycloheptatrienyl)iminophosphoranes (3a, b) and their thermal conversion to N-(1,3,5-cycloheptatrienyl)iminophosphoranes (5a,b) have been studied. The kinetic study of the 1,5-hydrogen migration of 3a,b to N-(1,3,6-cycloheptatrienyl)iminophosphoranes (4a,b) has also been investigated. The reaction of 5b with α-bromoacetophenone derivatives has provided a novel route to the 1-azaazulene ring system, albeit in low yields.
  • Yoo Tanabe
    1989 Volume 62 Issue 6 Pages 1917-1924
    Published: 1989
    Released: June 27, 2006
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    Inter and intramolecular condensations (the Claisen and the Dieckmann condensations) between ester functions have been performed by the combined use of dichlorobis(trifluoromethanesulfonato)titanium(IV) (= dichlorobis(triflato)titanium(IV)) and tertiary amine under mild reaction conditions. These results led to the development of the selective (crossed) Claisen and Dieckmann ester condensation between methoxymethyl ester and methyl ester, in that, dichlorobis(triflato)titanium(IV) contribute to control the direction of the reaction.
  • Katsuhiro Saito, Tatsuji Sato, Hiraku Ishihara, Kensuke Takahashi
    1989 Volume 62 Issue 6 Pages 1925-1929
    Published: 1989
    Released: June 27, 2006
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    Reactions of the sodium salts of tosylhydrazones of several heteroaromatic aldehydes with an equimolar amount of acrylonitrile afforded the corresponding cyclopropane derivatives as the major products accompanied by small amounts of pyrazole derivatives. On the other hand, reactions using ten-molar equivalents of acrylonitrile gave pyrazole derivatives as major products.
  • Ryuichi Shiba, Miyuki Takahashi, Toichi Ebisuno, Michiaki Takimoto
    1989 Volume 62 Issue 6 Pages 1930-1933
    Published: 1989
    Released: June 27, 2006
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    The investigation of the reactions of urea and its methyl derivatives with formaldehyde elucidated the formation pathway of 3,5-bis(methoxymethyl)perhydro-1,3,5-oxadiazin-4-one. 1) The addition of formaldehyde to urea became increasingly difficult according to the increase of the number of added formaldehyde molecules, probably because of the steric hindrance of the hydroxymethyl groups. 2) 3,5-Bis(methoxymethyl)perhydro-1,3,5-oxadiazin-4-one was concluded to be derived from urea via tris(hydroxymethyl)urea and 3-(hydroxymethyl)perhydro-1,3,5-oxadiazin-4-one but not via tetrakis(hydroxymethyl)urea or perhydro-1,3,5-oxadiazin-4-one.
  • Kensuke Shima, Jun Kimura, Kouhei Yoshida, Masahide Yasuda, Kiyohisa I ...
    1989 Volume 62 Issue 6 Pages 1934-1942
    Published: 1989
    Released: June 27, 2006
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    Molecular structures of diarylcyclobutanes (1–6) have been determined by single-crystal X-ray analyses. Although the distances and angles of the cyclobutane rings are relatively normal, the torsional angles between the aryl ring and the plane involving the ipso carbon and the aryl-substituted carbons of cyclobutane ring are close to 90° in cases of 1–4, but very small (2.3–11.3°) in cases of 5 and 6; conformations of the aryl substituents are highly restricted by the rigid tricyclic structure or by nonbonding interactions between the vicinal substituents in the cis configuration. Restricted conformations are closely related to the different reactivities of the cyclobutane in photochemical, thermal, and radiation-induced ring-splitting reactions. The structure-reactivity relationships are discussed in terms of the conformation-controlled π–σ orbital interactions associated with the capabilities of the π electron systems in through-bond coupling.
  • Masahide Yasuda, Kouhei Yoshida, Kensuke Shima, Chyongjin Pac, Shozo Y ...
    1989 Volume 62 Issue 6 Pages 1943-1950
    Published: 1989
    Released: June 27, 2006
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    Regiochemistry and reactivities in the thermal ring-splitting reactions of diarylcyclobutanes (1–5) have been studied and shown to depend on the stable conformations and rotational mobilities of the aryl substituents. The reactions of 1 and 2 result in a regiospecific symmetric cleavage to give indene or styrene along with significant isomerization of 2 to 3. In the cases of 3–5 both the symmetric and unsymmetric cleavages competitively occur with decreasing symmetric-to-unsymmetric ratios with an increase in methyl substitution. The olefin products from 4 are mixtures of cis- and trans-2-butene, cis- and trans-β-methylstyrene, and trans-stilbene. Thermochemical analyses combined with product analyses indicate that the symmetric cleavage of 1 and the unsymmetric cleavage of 3 proceed with a concerted mechanism, whereas 1,4-biradicals are involved in the other reactions. Structure-reactivity relationships of the present reactions are discussed in terms of mixing of the σ* character in a bonding MO by specific π–σ* interactions, depending on the conformational situations of the aryl groups and in terms of the steric effects which destabilize 1,4-biradicals as well as transition states of the biradical fragmentation to the olefins.
  • Chyongjin Pac, Kazuyoshi Go-an, Shozo Yanagida
    1989 Volume 62 Issue 6 Pages 1951-1959
    Published: 1989
    Released: June 27, 2006
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    The photolyses of cis-transoid-cis-cyclobutadiindene (1), cis-2-phenylcyclobut[a]indene (2), cis-1,2-diphenylcyclobutane (3), the trans isomer (4), and its dimethyl (5) and tetramethyl (6) derivatives have been investigated to explore stereoelectronic factors controlling the excited-state reaction courses for the ring cleavages. The symmetric ring cleavage occurs regiospecifically in the cases of 1–3 and with 98% specificity in the case of 4. The photolysis of 5 results in both the symmetric and the asymmetric cleavages in a ca. 1 : 3 ratio accompanied by substantial losses of stereointegrity in the olefin formation, and the regiospecific asymmetric cleavage occurs in the case of sterically more congested 6. The ring-cleavage efficiencies systematically decrease in the order 1>2>3>4>5>6 and reveal negative temperature dependences, particularly in the cases of 1, 5, and 6. The features of the reactions are in parallel with stable conformations and conformational mobilities of the aryl groups associated with different π–σ orbital interactions, while the spectroscopic properties of the cyclobutanes are essentially identical with those of benzene chromophores with little electronic perturbation. The photolytic ring-cleavage reactions are discussed in terms of crossing from the localized 1π,π* state to a σ* hypersurface, in which conformation-controlled orbital interactions play important roles. The final products are formed via a pericyclic minimum which might be biradicaloid in nature.
  • Shuji Kanemasa, Kazushige Sakamoto, Otohiko Tsuge
    1989 Volume 62 Issue 6 Pages 1960-1968
    Published: 1989
    Released: June 27, 2006
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    A variety of aldehydes, containing enolizable aldehydes other than acetaldehyde can be used in the generation method of nonstabilized azomethine ylides by decarboxylative condensation of α-amino acids. Reactivity of the nonstabilized ylides was examined in intermolecular and intramolecular cycloadditions with olefins; stereoselectivity of the intramolecular cycloaddition using nonstabilized ylides was compared with that of ester-stabilized ylides.
  • Hajime Fujinuma, Masaru Hosokawa, Tohru Suzuki, Mitsuo Sato, Shizen Se ...
    1989 Volume 62 Issue 6 Pages 1969-1975
    Published: 1989
    Released: June 27, 2006
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    The reaction of 1-ethoxy-2,4-dinitronaphthalene (1) with pyrrolidine or piperidine in dimethyl sulfoxide occured in two stages (Stages I and II). In the stage I, a σ-adduct forms at such a rate as is measured by a stopped-flow technique, and in the stage II it decays at a slower and spectrophotometrically measurable rate. The pyrrolidine system is more reactive than the piperidine system in the stages I and II, with the former reactivity in the stage II being ca. 11000 times higher than the latter. This huge difference was found by NMR evidence to stem from the structure of transition state in the stage II. Further, the activation parameters were determined, which corresponded to such difference in reactivity very well.
  • Mitsuaki Narita, Yoshihisa Kojima, Shizuko Isokawa
    1989 Volume 62 Issue 6 Pages 1976-1981
    Published: 1989
    Released: June 27, 2006
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    Fragment condensations between amino- and carboxyl-components of hydrophobic decapeptides, which have a β-sheet structure in the solid state and are insoluble in DMF, NMP, and DMSO, were examined in a mixture of CH2Cl2 and TFE (4/1, v/v) using various coupling reagents. By the use of DCC and HOBt as coupling reagents, the reaction proceeded smoothly in moderate yield to give eicosapeptides. These have a stable helical structure in the solid state and are easily soluble in a variety of organic solvents. The hydrophobic eicosapeptides obtained were subjected to a successive coupling reaction in CH2Cl2 alone to give helical tetracontapeptides in high yield, which also have high solubility in various organic solvents of low polarity. The solubility of hydrophobic helical peptides presents a solubility feature of helical peptides which are obtained as peptide intermediates in protein synthesis. The synthetic strategy for helical peptides and proteins is discussed in connection with the solubility prediction method.
  • Kunio Mochida, Takato Yamauchi, Hideki Sakurai
    1989 Volume 62 Issue 6 Pages 1982-1985
    Published: 1989
    Released: June 27, 2006
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    A chiral germyl radical produced from an optically active hydrogermane, 1-NpPhMeGe*H, abstracted a chlorine atom from CCl4 to give the corresponding chlorogermane with retention of configuration. Progressive dilution of CCl4 with cyclohexane demonstrated that the chiral germyl radical could also undergo inversion. A mechanism in which inversion of the chiral germyl radical competed with chlorine abstraction was proposed and the relative rate of chlorine abstraction to inversion (kClkinv) of the chiral germyl radical was found to be (0.52±0.13) mol−1 dm3 at 80 °C. The rate constant for the chlorine abstraction (kCl) by germyl radicals with CCl4 was determined to be (6.6±1.0)×108 s−1 mol−1 dm3 by laser-photolysis experiments. By using this rate constant, the kinv value for the chiral germyl radical was estimated to be ca. 2×109 s−1.
  • Yuji Hidaka, Yasutsugu Shimonishi
    1989 Volume 62 Issue 6 Pages 1986-1994
    Published: 1989
    Released: June 27, 2006
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    A new method was developed for determination of disulfide pairings in peptides. This method consisted in the synthesis of peptides with deuteriocysteine residues at given positions and the analysis of deuteriocystine generated in the acid hydrolyzates of the synthetic peptides by fast atom bombardment mass spectrometry. The availability of this method was confirmed by its application for determining the positions of disulfide linkages in a heat-stable enterotoxin of enterotoxigenic Escherichia coli.
  • Ichiro Hirao, Masahide Ishikawa, Hiroyuki Hori, Kimitsuna Watanabe, Ki ...
    1989 Volume 62 Issue 6 Pages 1995-2001
    Published: 1989
    Released: June 27, 2006
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    Nonadeca- and octadecaribonucleotides corresponding to the D-loop of tRNAPhe from yeast and the leader sequence of phage f1 coat protein mRNA were synthesized by the activated phosphotriester method. Coupling yield in the synthesis of oligoribonucleotides depended on the extent of nucleosides loaded on controlled pore glass beads (CPG). N-Acyl-5′-O-dimethoxytrityl-2′-O-tetrahydropyranyl derivatives were used as fully protected ribonucleotide monomer units. The 18mer and 19mer corresponding to the D-loop did not serve as substrates for tRNA (guanosine-2′-)methyltransferase from T. thermophilus, but inhibited methylation of the 5′-half fragment of tRNAPhe. This indicates that both fragments possess some affinity with the enzyme.
  • Yoshihiro Kanda, Yasuhiko Yamamoto, Yoshio Inoue, Riichirô Ch\ { ...
    1989 Volume 62 Issue 6 Pages 2002-2008
    Published: 1989
    Released: June 27, 2006
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    6-O-α-D-Glucopyranosyl-α-cyclodextrin (G1-α-CD)-p-nitrophenol (pNP) inclusion complex has been characterized by high resolution 1H and 13C NMR. From 1H NMR measurements it is concluded that G1-α-CD forms a 1 : 1 inclusion complex with pNP at both pD 7 and 10, and the dissociation constants for their complexation are quite similar to those for α-CD–pNP complexation, suggesting that G1-α-CD and α-CD have a similar ability of complexation with pNP. The geometry of G1-α-CD–pNP complex was found to be similar to that of α-CD–pNP complex. Analysis on the NMR spectral parameters of G1-α-CD have revealed that the asymmetric nature of G1-α-CD molecule is enhanced by complexation with pNP.
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