Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 70 , Issue 7
Showing 1-32 articles out of 32 articles from the selected issue
  • Shin-ichi Ishiguro
    1997 Volume 70 Issue 7 Pages 1465-1477
    Published: 1997
    Released: June 13, 2006
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    Formation thermodynamics and structure of halogeno and pseudo-halogeno complexes of transition metal(II) and lanthanide(III) ions have been studied in N,N-dimethylacetamide (DMA) and hexamethylphosphoric triamide (HMPA), and compared with those in N,N-dimethylformamide (DMF). Significant differences in the formation thermodynamics and structure among solvents has been explained in terms of a solvation steric effect. A structural survey by EXAFS demonstrates that solvent coordination number of a solvate metal ion is kept unchanged (weak solvation steric effect) or reduced (strong solvation steric effect) when the metal ion is transferred to DMA or HMPA, respectively, from DMF. DMA usually exhibits a weak solvation steric effect. It elucidates that a weak solvation steric effect of DMA is ascribable mainly to a distortion of the M–O–C–N dihedral angle. The solvent effect operates for a complex with a coordination number larger than four in DMF, but it does not for a complex of four-coordination. Lanthanide(III) ions exhibit a specific solvation steric effect, and an outer-sphere bromo complex in DMF changes to an inner-sphere complex in DMA. Besides, the solvent coordination number varies with solvent composition in DMF–DMA mixtures, and the variation manner strongly depends on the metal ion or the ionic radius. HMPA shows a strong solvation steric effect, and halogeno complexation is significantly enhanced in HMPA relative to that in DMF, although HMPA has a stronger electron-pair donating ability. The coordination number is four or five, and the M–O(HMPA) bondlength is significantly shortened.
  • Kiyoyuki Yamada, Hideo Kigoshi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1479-1489
    Published: 1997
    Released: June 13, 2006
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    This account describes the chemistry of the bioactive compounds isolated from the sea hares belonging to two genera: Aplysia and Dolabella. The bioactive compounds are classified as i) polyketides, ii) terpenes, iii) peptides and depsipeptides, and iv) others. Special emphasis is placed on the chemistry of cytotoxic compounds such as aplyronines and dolastatins that were obtained in our laboratory: Their isolation, structural elucidation, synthesis, and selected bioactivities data are summarized.
  • Tisato Kajiyama, Keiji Tanaka, Atsushi Takahara
    1997 Volume 70 Issue 7 Pages 1491-1503
    Published: 1997
    Released: June 13, 2006
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    Surface molecular motions of monodisperse polystyrene (PS) films, binary and ternary PS blend films, and polydisperse PS films were investigated on the basis of scanning force microscopic (SFM) measurements at 293 K. The monodisperse PSs were synthesized by a living anionic polymerization. It was revealed that the magnitude of the surface dynamic storage modulus E′ was remarkably lower than that for its bulk state, whereas, the surface dynamic loss tangent tan δ value was fairly higher than that for its bulk state, in the case of the monodisperse PS with number-average molecular weight (Mn) lower than 26.6 k. The scanning viscoelasticity microscopic (SVM) measurements showed that the surface of the monodisperse PS film with Mn lower than 26.6 k was in a glass–rubber transition state even at 293 K, even though the bulk Tg was far above 293 K. Lateral force microscopic (LFM) measurements for the monodisperse PS films also revealed that the magnitude of lateral force was dependent on the scanning rate of the cantilever tip in the case of Mn lower than 40.4 k. It is well accepted that the scanning rate dependence of lateral force appears in the case that the surface of the PS film is in a glass–rubber transition state. LFM results correspond well to SVM ones if the scanning rate of the cantilever tip for LFM measurement was converted to the measuring frequency for SVM measurement. Active thermal molecular motion on the polymeric solid surface was explained by the excess free volume induced due to the surface localization of chain end groups. The surface enrichment of chain end groups was confirmed by dynamic secondary ion mass spectroscopic (DSIMS) measurement.
    The binary and the ternary PS blends were prepared by mixing the monodisperse PSs with different molecular weights. The commercially available PSs were also used as the polydisperse PS samples. LFM and SVM measurements revealed that the surface of the binary and the ternary PS blend films was in a glass–rubber transition state even at room temperature, when the component with Mn lower than ca. 30 k existed. More active surface molecular motion compared with the bulk one for the binary and the ternary PS blend films can be explained by the surface segregation of the lower molecular weight component. The surface enrichment of lower molecular weight chains was confirmed on the basis of the DSIMS measurement by using the deuterated PS as the one component. In the case of the polydisperse PS film, even though the molecular weight distribution was broad and a somewhat lower molecular weight component was mixed, the active surface molecular motion showing a glass–rubber transition state was remarkably depressed at room temperature in comparison with the case for monodisperse PS film with the corresponding Mns. The difference on the surface thermal molecular motion between monodisperse and polydisperse PS films might be explained on the basis of the chemical structure of the chain end groups. Also, in the case that the molecular weight component lower than ca. 30 k was not present in the system in spite of the broad molecular weight distribution, the surface molecular motion corresponding to the glass–rubber transition was not observed at room temperature.
    Also, two-dimensional mapping of topography and surface E′ for the [PS/poly(methyl vinyl ether)] ultrathin blend film was carried out by using atomic force microscopy (AFM) and SVM, respectively. The combination of topographical and surface mechanical images could characterize the interfacial structure on nanometer scale.
  • Kohji Maeda, Wataru Hyogo, Shuzo Nagami, Sorin Kihara
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1505-1515
    Published: 1997
    Released: June 13, 2006
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    Novel oscillations of membrane current or membrane potential were observed when the transfer of Na+ from one aqueous solution (W1) containing 0.1 M NaCl to another (W2) in the absence of Na+ through a liquid membrane (LM) containing dilute Na+ was forced by an applied membrane potential or membrane current, respectively. The current oscillation was induced by the addition of acetylcholine in W1, and inhibited by the addition of such hydrophobic ions as tetraalkylammonium ions or glutamate ion in W1. These oscillations were similar to those at biomembranes with so-called “sodium channels” as regards both induction and inhibition, though the liquid membrane system did not contain any channel proteins. The current and potential oscillations were also inhibited by the addition of bovine serum albumin in W2. The mechanisms of the oscillations, the induction and the inhibitions were elucidated by referring to voltammograms for the ion transfer through a membrane as well as those at aqueous/membrane interfaces, and by taking into account the adsorption of Na+ at the LM/W2 interface. Various LM systems which exhibit the oscillations accompanied by transports of ions other than Na+ were also investigated, and the general feature of the oscillations of membrane current or potential is discussed.
  • Nikolai Tyutyulkov, Fritz Dietz, Klaus Müllen, Christian Küb ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1517-1521
    Published: 1997
    Released: June 13, 2006
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    The magnetic properties of a new class of high-spin organic 1-D polymers were studied theoretically. The polymers have the same topology as poly(1,3-phenylenemethylene)s (PMP) and are derived from the latter by substitution of the exocyclic radical center –CR– by –B•−R–, –N–, –N+•H–, –O+•– or –S+•–. All of these polymers possess a narrow half-filled band (HFB) within the energy gap. The nature of spin-exchange interactions of π-electrons within the HFB has been investigated. The three components of the effective exchange integral, Jeff, in the Heisenberg Hamiltonian representing the potential (direct), kinetic and exchange (due to the spin polarization—indirect exchange) interaction of the π-electrons in the HFB were calculated. In all cases, the potential (Coulomb) exchange was the main contribution to the ferromagnetic (Jeff > 0) exchange interaction.
  • Hiroaki Kato, Yoshimasa Takahashi
    1997 Volume 70 Issue 7 Pages 1523-1529
    Published: 1997
    Released: June 13, 2006
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    This paper describes a three-dimensional (3D) structural feature search, or motif search, of proteins using SS3D-P. Our present approach is based upon the use of a substructure searching program for small organic molecules, SS3D, reported in our previous work. In SS3D-P, the 3D structure of a protein is approximated with the coordinates of α-carbon atoms of the main chain, and treated as a molecular graph that is represented using a distance matrix. The program allows us to specify the tolerance value of the inter-residual distances to be compared. Several characterization schemes are also available for the different amino acid residues that can be distinguished. The program we have developed was validated by search trials with 3D query patterns of known protein motif structures: the P-loop, the EF-hand, and the Zinc finger motif using Protein Data Bank (PDB) structure files.
  • Hidenori Matsuzawa, Yoshihiro Osamura
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1531-1537
    Published: 1997
    Released: June 13, 2006
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    The geometrical structures and stabilization energies of benzene–chlorine complex were studied theoretically using an ab initio molecular orbital method. Full geometry optimization was carried out for four models ((1) [On Center (C6v symmetry)], (2) [On Atom (Cs symmetry)], (3) [On Bond (Cs symmetry)] and (4a,b) [Resting (Cs symmetry)]) with restricted Hartree–Fock (RHF) and second-order Møller–Plesset perturbation (MP2) methods, MP2 (Frozen), and MP2 (Full), using various basis sets. The RHF method is not good enough to describe the molecular structure and interaction energy of the complex. The geometry obtained with the MP2/DZP + d method has good agreement with the X-ray crystal structure. An unusual basis set superposition error (BSSE) was found when the MP2 method with a frozen-core approximation was applied to evaluate the interaction energy. In the MP2 (Full) method, in which the inner-core wavefunctions was correlated, the reasonable stabilization energy is obtained. The BSSE-corrected interaction energies (ΔE(corr.)) of models(1), (2), and (3) are −6.63, −8.44, and −8.14 kJ mol−1, respectively. The most stable structure of the benzene–chlorine complex was calculated to be model (2). Model (3) lies at only 0.3 kJ mol−1 higher energy than model (2) in the MP2(Full)/DZP + d calculation. The position of chlorine would be very flexible on the benzene ring, and the molecular structure of the complex is easily interchangeable between models (2) and (3).
  • Hexing Li, Chun Shen
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1539-1543
    Published: 1997
    Released: June 13, 2006
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    In a batch reactor, an absolutely homogeneous inorganic Belousov–Zhabotinskii (BZ)-type oscillator has been designed in the system of BrO3–H2PO2–Mn2+–Fe(phen)32+–H2SO4. The oscillations of both [Br] and [Mn3+]/[Mn2+] as well as [Fe(phen)33+]/[Fe(phen)32+] were observed by monitoring the changes of either the potential on a bromide electrode or the absorbance at the maximum absorbance wavelength for Mn3+ and Fe(phen)33+, respectively. Both of those two metallic ions are essential in the present system to give rise to the oscillations; their roles in the oscillation are discussed. It is found that Mn2+ can not be replaced by other substances, while Fe(phen)32+ can be replaced by either N2 flow or acetone. However, it can not be replaced by other metallic ions, including Mn2+ and Ce3+. Those results suggest that Mn2+ is the real oscillating catalyst for an autocatalytic formation of HBrO2 and Fe(phen)32+ is a catalyst for the catalytic reduction of Br2 by H2PO2 to remove any excess Br2 produced during the oscillations.
  • Masahiko Arai, Makane Fukushima, Yoshiyuki Nishiyama
    1997 Volume 70 Issue 7 Pages 1545-1549
    Published: 1997
    Released: June 13, 2006
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    The interrupted temperature-programmed desorption of carbon monoxide was used to characterize the surface heterogeneity of supported platinum catalysts. The surface of platinum particles is divided into two different groups of desorption sites. For one group, the surface diffusion of carbon monoxide takes place easily, and it desorbs at low temperatures. For the other, the desorption of carbon monoxide requires higher temperatures, and surface diffusion does not occur. For the latter group, the distribution of the activation energy of desorption is determined by a method that the authors have recently developed (Appl. Surf. Sci., 89, 11 (1995)).
  • Hisahiro Einaga, Makoto Misono
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1551-1557
    Published: 1997
    Released: June 13, 2006
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    The photocatalytic decomposition of 4-chlorophenol with a Keggin-type heteropolytungstate, PW12O403− (abbreviated as PW123−), under aerated conditions has been investigated in an aqueous or water-acetonitrile solution by using a 300 W Xe arc lamp at 303 K. The kinetics of the reaction indicated that the reaction proceeds via a Langmuir–Hinshelwood (or Michaelis–Menten) type mechanism, in which the complexation between the heteropolyanion and 4-chlorophenol exists as a pre-equilibrium step. This complex formation was evidenced by the observation of a new band at λ < 650 nm and the enhancement of the solubility of 4-chlorophenol in water in the presence of PW123−. The intensity of the new band varied in parallel with the reaction rate, depending on the concentrations of 4-chlorophenol and acetonitrile. This fact was consistent with the mechanism proposed.
  • Noriyuki Ojima, Kunihiko Gekko, Kiwamu Yamaoka
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1559-1572
    Published: 1997
    Released: June 13, 2006
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    The dependence of reduced dichroism (Δε/ε) of sonicated rodlike title triplexes with the counterion Mg2+, (dA)n·(dT)n·(dT′)n and (rA)n·(rU)n·(rU′)n, on the wavelength (190—300 nm) and on the applied-field strength (3.8—23.1 kV cm−1) was studied in aqueous ionic solutions at 7 °C. The sonicated samples were fractionated and well-characterized by the gel-permeation chromatography/low-angle laser light-scattering method. The reduced dichroism saturated at infinitely high electric fields ((Δε/ε)s) was estimated to be −1.22 for (dA)n·(dT)n·(dT′)n and −1.09 for (rA)n·(rU)n·(rU′)n, by fitting the observed Δε/ε values at 260 nm to a theoretical orientation function. The electric linear dichroism (ELD) spectra, i.e., the dependence of (Δε/ε)s on the wavelength, of (dA)n·(dT)n·(dT′)n and (rA)n·(rU)n·(rU′)n were determined. The measured ELD spectra were simulated by assigning the appropriate roll (θR) and tilt (θT) angles to the constituent bases. The most probable θR and θT values, determined for each triplex, indicate that the structures of triple helices both belong to an “A-form” family. The constituent bases in base-triple do not lie on a common plane. From an analysis of transient decay signals, the translation per base-triple (h) was estimated for each triplex. The structures of the present high molecular-weight triple-stranded helices in aqueous solution were determined for the first time and the plausible structural models were constructed from the experimentally evaluated sets of θR and θT.
  • Yoneichiro Muto, Hiroshi Horie, Tadashi Tokii, Michio Nakashima, Masay ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1573-1581
    Published: 1997
    Released: June 13, 2006
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    ESR, IR, and electronic reflectance spectral data are presented for dimeric (trichloroacetato)copper(II) complexes, of which magneto-structural data are available: The larger is the distortion of the coordination geometry from square pyramidal (SP) toward trigonal bipyramidal (TBP), the longer is the Cu···Cu distance in the dimers. The elongation of the Cu···Cu distance is accompanied by a reduction of the zero-field splitting parameter (D), the anisotropic exchange parameter (Dex), and the peak separation of the two peaks in the electronic spectra (). The splitting of the carboxylato stretching frequencies, , increases with the distortion. Good linear correlations have been observed between the values of these parameters and the Cu···Cu distances. The axial ESR spectra with g// > g and the electronic spectra suggest that the ground state of the Cu atom is essentially dx2 − y2, even in the metal geometry of the greatest distortion toward TBP (the z-axis is along the longest Cu–O bond).
  • Katsuma Hiraki, Shu-ichi Kira, Hiroyuki Kawano
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1583-1592
    Published: 1997
    Released: June 13, 2006
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    Dihydridoruthenium(II) complex [RuH2(CO)(PPh3)3] (1) reacts with methyl benzoate in the presence of an olefin at 110 °C to afford some dicarbonylruthenium(O) species [Ru(CO)2(PPh3)3] (2) and “Ru(CO)2(PPh3)2L” (L = the olefin or the ester). A tricarbonylruthenium(O) complex [Ru(CO)3(PPh3)2] (3) is formed at higher reaction temperature. The experiment using 13C-enriched methyl benzoate reveals that the second and the third carbonyl ligands are mainly derived by subtraction of the carbonyl group from the ester. When the reaction is carried out in the presence of triethoxyvinylsilane, a part of the second and the third carbonyl groups is derived from the ethoxy group of the silane, because 1 reacts with the silane at 110 °C in the absence of the ester to afford 2 and 3. The formation ratio of 2 and 3 is affected by the type of olefins used; selective formation of 2 and 3 is achieved when triethoxyvinylsilane is used, whereas allylbenzene or cyclooctene affords merely a mixture of the di- and tricarbonyl species. The reaction mixture containing 2 and “Ru(CO)2(PPh3)2L” is exposed to air to give a peroxo complex [Ru(η2-O2)(CO)2(PPh3)2] (4) smoothly. The molecular structures of 2 and 4 are determined by the single crystal X-ray diffraction method. The complex 2 has a distorted trigonal bipyramidal coordination geometry with two equatorial CO ligands, whereas the complex 4 has a distorted octahedral structure.
  • Sen-ichi Aizawa, Shigeo Iida, Kayoko Matsuda, Shigenobu Funahashi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1593-1597
    Published: 1997
    Released: June 13, 2006
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    The solvent exchanges of nickel(II), iron(II), and manganese(II) ions in 1,3-propanediamine (tn) and n-propylamine (pa) have been studied by the 14N NMR line-broadening method. The rate constants of the amine exchanges for the first-row transition metal ions are in the order of ethylenediamine (en) < tn < pa, which is largely affected by the difference in the activation enthalpies. The differences in the rate constants and the activation enthalpies among the three amine solvents become greater along the series from manganese(II) ion to nickel(II) ion. These kinetic results have clarified that the differences in the kinetic chelate strain effect in the transition state and the chelate strain effect in the ground state can be attributed to the difference in the chelate ring sizes and the ion radii.
  • Tatsuya Kawamoto, Hiro Kuma, Yoshihiko Kushi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1599-1606
    Published: 1997
    Released: June 13, 2006
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    The reactions of 2-phenylbenzothiazoline with [M(CH3COO)2]·4H2O (M = Co(II) and Ni(II)) afford the complexes [M(phbt)2 ] (phbt = 2-(phenylmethyleneamino)benzenethiolato) via a ring opening reaction of 2-phenylbenzothiazoline. Spectroscopic data indicate that the cobalt and nickel atoms occupy a tetrahedral and a square planar N2S2 environment, respectively. The single crystal X-ray structure of [Ni(phbt)2] is redetermined and this complex shows a monohelical geometry. Crystal data: [Ni(phbt)2], monoclinic, C2/c, a = 23.065(4); b = 6.924(2); c = 13.809(2) Å; β = 102.64(1)°; V = 2152.0(9) Å3; Z = 4, R = 0.052 (Rw = 0.050). The toluene solution of [Co(phbt)2] and that of [Ni(phbt)2] lead to the complexes [Co(ddbt)] and [Ni(ddbt)] (ddbt = bis-2,2′-(1,2-diphenylethylenediimine)benzenethiolato) through the carbon–carbon bond formation, respectively. The structural features of [M(ddbt)] (M = Co and Ni) point clearly to the neutral dithiolene-like charge distribution. These complexes [M(ddbt)] have the same chemical compositions as the starting complexes [M(phbt)2], and both can be correlated in a new valence isomerism. Crystal data: [Co(ddbt)], monoclinic, P21/n, a = 8.573(2); b = 24.486(3); c =10.771(1) Å; β = 102.08(2)°; V = 2211.0(9) Å3; Z = 4, R = 0.056 (Rw = 0.048); [Ni(ddbt)], monoclinic, P21/n,a = 8.631(10); b = 24.365(19); c = 10.798(4) Å; β = 102.69(6)°; V = 2215.2(33) Å3; Z = 4, R = 0.078 (Rw = 0.075).
  • Keiichi Tomishige, Yosuke Nagasawa, Uk Lee, Yasuhiro Iwasawa
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1607-1614
    Published: 1997
    Released: June 13, 2006
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    The catalytic property of a [PtMo6]/MgO catalyst prepared by using a [PtMo6O24]8− precursor for NO–CO reactions and a structural analysis by means of Pt L3- and Mo K-edge EXAFS spectroscopy was studied. The catalytic activity of the bimetallic ensemble catalyst appeared due to the incorporation of Pt ions into the MgO surface, where Pt4+ ions substituted Mg2+ ions in the first layer of the MgO surface. It seems that the NO–CO reaction proceeded on the Pt sites embedded in the MgO surface by a redox mechanism, whereas metallic Pt particles on MgO were inactive under the present reaction conditions, characterized by an in-situ EXAFS analysis.
  • Jun-ichi Tateiwa, Sakae Uemura
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1615-1619
    Published: 1997
    Released: June 13, 2006
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    Our previous structure assignment of two phenylbicyclooctanes obtained in Friedel–Crafts transannular alkylation of benzene with (Z,Z)-1,5-cyclooctadiene has been reinvestigated and partly corrected on the basis of 13C NMR spectral data, a separate preparation of an authentic sample, and MM3 calculation. The compounds assigned previously to exo-3-phenyl-cis-bicyclo[3.3.0]octane and exo-3-phenylbicyclo[3.2.1]octane among six products should be assigned to 1-phenyl-cis-bicyclo[3.3.0]octane and exo-3-phenyl-cis-bicyclo[3.3.0]octane, respectively, showing that almost all products have bicyclo[3.3.0]octane framework. A new preparative method for an authentic 1-phenyl-cis-bicyclo[3.3.0]octane and MM3 calculations of all products are also presented.
  • Sadayuki Matsuda
    1997 Volume 70 Issue 7 Pages 1621-1624
    Published: 1997
    Released: June 13, 2006
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    S-100 proteins, which are acidic Ca2+-binding proteins, exist in the brain and modulate enzymes and proteins as does calmodulin. In order to clarify some unique characteristics of S-100 proteins, the effects of mastoparan (MP) on the Ca2+ affinity of two S-100 protein isoforms (S-100a.a′, S-100b) in the presence of Zn2+ were examined using dialysis and stopped-flow methods. It was clearly demonstrated that the enhancement of S-100a.a′ was distinct from that of S-100b. Although the former isoform was affected only by the addition of MP, the latter was affected by MP or Zn2+.
  • Ramadan Ahmed Mekheimer, Nabil Helmi Mohamed, Kamal Usef Sadek
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1625-1630
    Published: 1997
    Released: June 13, 2006
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    The reaction of 4-hydroxy-6-methyl-2-pyridone 1 with benzylidenemalononitriles in an ethanolic solution containing a catalytic amount of piperidine and α-cyanoacrylic esters in pyridine affords the corresponding 4H-pyrano[3,2-c]pyridines. However, it’s reaction with 3-(cyanomethylene)-2-indolinones gives either 2-amino-3-quinolinecarbonitriles or ethyl 2-amino-5′,6′-dihydro-7′-methyl-2,5′-dioxospiro-[indoline-3,4′-[4H]-pyrano[3,2-c]pyridine-3′-carboxylate. In contrast, the reaction of 1 with 3-aryl-2-cyano-2-propenethioamides affords 3,3′-benzylidenebis[4-hydroxy-6-methyl-2(1H)-3-pyridinone]s. The reaction of the obtained 4H-pyrano[3,2-c]pyridines with acetic anhydride affords the corresponding fused system.
  • Zhi-hong Zhao, Kazuyuki Hasebe, Yoshikazu Sakagami, Tetsuya Osaka
    1997 Volume 70 Issue 7 Pages 1631-1637
    Published: 1997
    Released: June 13, 2006
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    The antibacterial activity of various electroplated coatings (cobalt, zinc, copper, and cobalt-containing alloys of nickel, zinc, chromium) was determined by a “Drop-method” antibacterial experiment against pathogenic bacteria (gram-positive bacterial S. aureus, MRSA, and gram-negative bacteria E. coli, P. aeruginosa). It was found that all of them possessed a higher antibacterial activity than stainless steel. The ralationship between the inhibitory capability for the growth of bacteria and the rest potential of the electroplated coatings was also investigated. A significant antibacterial activity of the coatings was apparently displayed by a rest-potential shift to more negative values. It was suggested that all of the tested bacteria fell closely within the lethal range when the rest potentials were lower than -543 mV. However, some amount of metal ions dissolved from various from various electroplated coatings was measured; accordingly, the inhibitory capability of the simulated dissolution concentrations of metal ions the growth of bacteria is discussed.
  • Mitsuaki Narita, Koji Sode, Shokichi Ohuchi, Mitsuo Hitomi, Yuka Murak ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1639-1648
    Published: 1997
    Released: June 13, 2006
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    φ, ψ Representations of three-dimensional structures of 125 globular proteins were depicted for analyzing conformational details in their secondary and tertiary structures. They can be drawn in the form of a two-dimensional diagram. The new type of representation of the protein tertiary structure can be used as a stereotyped finger printing for 125 protein molecules. It is powerful for a precise comparison of the relationship of the primary, secondary, and tertiary structures of homologous proteins. The precise or broad similarity between the patterns of proteins classified into the same family is obvious. This representation is also useful in readily recognizing all of the secondary structures as one progresses along the chain. Complicated three-dimensional structures of 125 globular proteins are easily recognized to be built up from only four secondary structures: helix, β-strand, β-turn, and unordered structure. A combination of intersegments hydrogen bonds among β-strands was also shown in the diagram. In order to demonstrate the usefulness of the diagram, 195 type-II β-turns were extracted from 125 proteins using the new type of two-dimensional φ, ψ diagrams. Their amino acid sequences were surveyed so as better to understand amino acid preferences previously observed. For their analysis, a normalized preference (NP) value of an amino acid residue at a particular position of the secondary structure is defined as the ratio of the average percentage composition at the position based on average percentage composition at large. The statistical significance of the NP-value used in this study is more simple and clearer than that of the d-test based on a normal distribution, which was used in the previous study. It is clearly shown that a high NP-value (5.0) of a single P residue for the position i + 1 of the type-II β-turn is an average preference of a variety of P residues in the middle of triplets consisting of consecutive amino acid residues. The NP-values of P residues, in the middle of 25 particular triplets are outstandingly high. Out of 400 possible P residues 322 kinds of P residues were found in 125 proteins. A remarkable high NP-value (8.8) of a single G residue for the position i + 2 is also an average preference of G residues in the middle of various triplets.
  • Hiroshi Ogawa, Shigeyoshi Kanoh, Masatoshi Motoi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1649-1657
    Published: 1997
    Released: June 13, 2006
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    Polyoxetanes anchoring the mesogen cores of p-spacer-substituted phenyl 4-(4-alkoxyphenylazo)benzoates through a pendant spacer, –CH2O(CH2)4O–, were prepared by a BF3-initiated cationic ring-opening polymerization of the corresponding oxetanes, followed by a fractional reprecipitation of the raw polymer products containing oligomer fractions. The polyoxetanes separated from the oligomers had their peak tops at molecular weights of around 10000—23000 in nearly mono- or dimodal molecular-weight dispersity curves determined by gel permeation chromatography, and indicated fan-shaped textures due to a smectic mesophase over a wide temperature range from about 250 °C to room temperature on heating and cooling processes by polarized optical microscopy. The formation of highly ordered assemblies of the pendant mesogens is ascribable to a cohesion of the 4-(4-alkoxyphenylazo)benzoate moiety in the mesogen core, which can form a larger dipole, due to forming a longer conjugated system from the ester carbonyl to the alkoxy tail, than that of the simple 4-alkoxybenzoate moiety of the mesogen core previously reported by us.
  • Toshiyuki Urano, Hideki Nagasaka, Shigeki Shimizu, Hiroto Ito, Makoto ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1659-1664
    Published: 1997
    Released: June 13, 2006
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    The sensitization mechanisms of ketocoumarin dyes with a radical-generating reagent (10,10′-carbonylbis[1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one] (KCD-J), 3,3′-carbonyldis[7-(diethylamino)-2H-1-benzopyran-2-one] (KCD-DA)) with 2,2′-bis(2-chlorophenyl)-4,4′,5,5′-tetraphenyl-1,1′-bi-1H-imidazole (BI) in a poly(methyl methacrylate) (PMMA) film have been investigated by laser-flash photolysis using a total-reflection cell. The triplet decay time of the dyes in a PMMA film was quenched by BI with a kqs of 1.3 and 0.60 × 105 mol dm−3 s−1 for KCD-J and KCD-DA. The fluorescence and initial absorption for KCD-DA were not quenched by BI in a PMMA film. The fluorescence was quenched at a quenching distance of 10.0 Å, and the initial triplet absorption was not quenched for KCD-J in a PMMA film.
    These results show that a nonstatic sensitization from the triplet to BI is the predominant process in a photoinitiation system containing KCD-DA, and that both static sensitization from the singlet excited state to BI and nonstatic sensitization from the triplet to BI exist in a photoinitiation system containing KCD-J.
  • Piotr Lulinski, Lech Skulski
    1997 Volume 70 Issue 7 Pages 1665-1669
    Published: 1997
    Released: June 13, 2006
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    An easy and cheap laboratory method is presented for the direct mono- and diiodination of a number of activated and deactivated arenes. The main iodination reactions occurred at the temperatures not exceeding 65 °C for 0.5—12 h in the anhydrous, strongly acidic liquid system, I2/AcOH/Ac2O/H2SO4, in the presence of prior dissolved CrO3 used as the oxidant. The yields of the pure iodinated products varied from 31% (for 3,5-diiodobenzoic acid) up to 90% (for 4-iodoanisole). So far, benzonitrile and some oxidizable aromatics, e.g. naphthalene, fluorene, xanthene, and thiophene, have been found to be unsuitable for the effective iodination. Nevertheless, this novel, simple method of direct iodination is worthy to be extended to other appropriate aromatics.
  • Susumu Saito, Itsuro Shimada, Yusuke Takamori, Michiaki Tanaka, Keiji ...
    1997 Volume 70 Issue 7 Pages 1671-1681
    Published: 1997
    Released: June 13, 2006
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    Michael addition of lithium enolates derived from ketones to a variety of α,β-unsaturated ketones was realized in the presence of aluminum tris(2,6-diphenylphenoxide) (ATPH). In this reaction, ATPH can be used as a carbonyl protector of α,β-unsaturated carbonyl substrates upon complexation, which facilitates the regioselective 1,4-addition of lithium enolates to Michael acceptors. Similarly, dianions of β-dicarbonyl compounds undergo Michael addition smoothly using ATPH as an effective promoter of the reaction. Subsequent regioselective, intramolecular aldol condensation was also demonstrated, leading to bicyclic carbon ring systems. Such systems are difficult to obtain by the Robinson annulation usually performed in protic media.
  • Yasushi Kawai, Kousuke Takanobe, Atsuyoshi Ohno
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1683-1686
    Published: 1997
    Released: June 13, 2006
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    The reduction of ethyl 2-methyl-3-oxobutanoate with Geotrichum candidum yields approximately equal amounts of the corresponding syn-(2R,3S)- and anti-(2S,3S)-3-hydroxy esters. When the microbe is incubated with methyl vinyl ketone (MVK) or chloroacetone before it is subjected to the reduction, the corresponding anti-(2S,3S)-hydroxy ester is obtained with exclusive enantio- as well as diastereoselectivity. In order to obtain more insight into the mechanism of this stereochemical control in microbial reduction, β-keto ester reductases were isolated and purified from the cells of G. candidum. Three dominantly competing enzymes were purified. One of them affords the anti-(2S,3S)-hydroxy ester selectively, whereas the others give the syn-(2R,3S)-hydroxy ester selectively. The rates of enzymatic reductions were measured in the presence and absence of an additive. Chloroacetone and MVK are competitive and suicide substrates, respectively, for the syn-enzymes, whereas they hardly affect the activity of the anti-enzyme. In the presence of an additive, the reduction of ethyl 2-methyl-3-oxobutanoate with G. candidum is catalyzed by the anti-enzyme only.
  • Masatoshi Asami, Seiichi Inoue
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1687-1690
    Published: 1997
    Released: June 13, 2006
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    The enantioselective addition of diethylzinc to aldehydes in the presence of a catalytic amount of several chiral diamines, (S)-2-(N,N-disubstituted aminomethyl)pyrrolidines, was studied. Relatively high selectivity was achieved in the case of aromatic aldehydes by employing 15 mol% of (S)-2-(1-pyrrolidinylmethyl)pyrrrolidine.
  • Hiroshi Uyama, Hirofumi Kikuchi, Shiro Kobayashi
    1997 Volume 70 Issue 7 Pages 1691-1695
    Published: 1997
    Released: June 13, 2006
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    Enzymatic ring-opening polymerization of a 13-membered lactone, 12-dodecanolide (DDL), was performed in the presence of acyclic esters in bulk by using lipase catalyst. The acyl group was introduced at the terminal by adding a fatty acid vinyl ester. Effects of the chain length and concentration of the vinyl ester on the introduced ratio (functionality) and molecular weight of the polymer have been examined. The quantitative acylation of the terminal was achieved by using lipases derived from Pseudomonas family under appropriate reaction conditions. Methacryl- and ω-alkenyl-type polyester macromonomers were synthesized by the polymerization of DDL in the presence of vinyl methacrylate and vinyl 10-undecenoate, respectively. This process could be extended to single-step synthesis of polyester telechelics. The polymerization in the presence of divinyl sebacate produced a telechelic polymer having a carboxylic acid group at each end. In using a fatty acid ethyl ester or an acetic acid alkyl ester as additive, on the other hand, the quantitative introduction of the corresponding acyl group was not achieved.
  • Kazuhiro Kobayashi, Harumi Takabatake, Tomohide Kitamura, Osamu Morika ...
    1997 Volume 70 Issue 7 Pages 1697-1699
    Published: 1997
    Released: June 13, 2006
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    When 2-(methylamino)benzonitrile was treated successively with magnesium bis(diisopropylamide), generated in situ from the reaction of ethylmagnesium bromide and diisopropylamine, and α,β-unsaturated carboxylic acid esters in diethyl ether at 0 °C, conjugate addition and enolate–nitrile coupling proceeded sequentially to give the corresponding 4-amino-1,2-dihydro-3-quinolinecarboxylates in isolated yields ranging from 36 to 79%.
  • Hiromichi Hayashi, Takeo Ebina, Yoshio Onodera, Takashi Iwasaki
    1997 Volume 70 Issue 7 Pages 1701-1708
    Published: 1997
    Released: June 13, 2006
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    The uptake of strontium ions from an aqueous solution by fibrous cerium(IV) bis(monohydrogenphosphate) has been studied from the viewpoints of the immobilization of strontium in radioactive waste by a batchwise operation in the temperature range from 25 to 250 °C. Strontium ions can be exchanged below 100 °C following an ion-exchange reaction between hydrogen ions of the phosphate groups. In contrast, strontium ions can be effectively immobilized under hydrothermal conditions accompanied by a structural change of the exchanger, where divalent strontium ions are incorporated into the monazite-like compound to compensate tetravalent cerium ions in trivalent cerium orthophosphate system. This phenomenon is peculiar to alkaline earth metal ions, since the monazite-like compounds were obtained in the presence of Ca2+ and Ba2+, while this phenomenon was absent in the presence of Cu2+ or Ni2+.
  • Chieko Uchida, Kaori Wakamatsu, Yasuko Iizuka, Kouki Oguma, Masanao Oy ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 7 Pages 1709-1715
    Published: 1997
    Released: June 13, 2006
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    N-Carboxy-Nin-formyltryptophan anhydride (4-(L-1-Nin-formylindol-3-ylmethyl)-2,5-oxazolidine dione, Trp(Form) NCA) was synthesized by formylation of the indole group of tryptophan, followed by N-carboxylation. The reactivity of copolymerization of Trp(Form) NCA with N-carboxy-L-alanine anhydride (4-methyl-1-2,5-oxazolidinedione, L-Ala NCA) was higher than that of Trp NCA. The helix contents of the formed copolypeptides, estimated by CD spectra, were remarkably decreased at a content of about 27% of Trp(Form). The content of Trp(Form) residue needed to destroy helix conformation in the copolypeptides was more than that of Trp residue of 8%.
  • Hiroki Ago, Koji Nagata, Kazunari Yoshizawa, Kazuyoshi Tanaka, Tokio Y ...
    1997 Volume 70 Issue 7 Pages 1717-1726
    Published: 1997
    Released: June 13, 2006
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    The interactions between carbon layers and lithium atoms are described with a semiempirical molecular orbital method in order to clarify the Li storage mechanism in amorphous carbon (a-C) materials used in Li ion rechargeable batteries. The general electronic and geometric structures of Li-doped a-C materials are investigated using ovalene (C32H14) as a model carbon structure. The following results are obtained. (i) The intercalation of Li atoms proceeds preferentially up to the C6Li configuration, followed by the absorption of Li atoms on the surface of the carbon layer. (ii) The adsorption of Li atoms can occur even on the nearest neighbor site and can form Li cation clusters commensurate with the carbon lattice. (iii) Li atoms located at the acene-edge sites are more stable than those at the phenanthrene-edge sites. This result suggests that the acene-edge structure is favorable for carbon anode materials. (iv) Substitution of the carbon skeleton by heteroatoms such as boron and nitrogen is not effective for Li storage.
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