Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 73 , Issue 1
Showing 1-33 articles out of 33 articles from the selected issue
  • Juzo Nakayama
    2000 Volume 73 Issue 1 Pages 1-17
    Published: 2000
    Released: October 31, 2001
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    The first topic of the present article involves recent advances in the chemistry of thiophene 1-oxides. Next is the chemistry of the parent thiophene 1,1-dioxide, which is followed by that of congested thiophene 1,1-dioxides, where emphasis is placed on their syntheses and synthetic applications. The chemistry of 1-imino, 1,1-diimino, and 1-imino-1-oxo derivatives of thiophenes is then described. Finally, the newborn chemistry of selenophene 1-oxides and 1,1-dioxides is discussed.
  • Teruhisa Komura, Kouji Mori, Takahiro Yamaguchi, Kousin Takahashi
    2000 Volume 73 Issue 1 Pages 19-27
    Published: 2000
    Released: October 31, 2001
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    The kinetic parameters of charge transport in composite-modified electrodes were measured as a function of the electrode potential, film thickness, solution pH, and counter ion composition by electrochemical impedance spectroscopy. The impedance characteristics of composite films were analyzed on the basis of the diffusion-migration transport of both holes and protons in the film. Incorporation of the polyanion with the host matrix produced a more compact deposite. A slow growth of the composite film during electropolymerization was ascribed mainly to its low electronic conductivity caused by poor contacts among polyaniline chains. Poly(styrenesulfonic acid) lowered the coupled diffusion coefficient of the charge carriers by a factor of ten. The relationships between the kinetic parameters and the oxidation and protonation levels of polyaniline suggested that the rate of charge transport through the composite film was controlled by electron transport, which occurred probably via interchain electron hopping.
  • Kazunari Yoshizawa, Takashi Yumura, Yoshihito Shiota, Tokio Yamabe
    2000 Volume 73 Issue 1 Pages 29-36
    Published: 2000
    Released: October 31, 2001
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    The so-called ``α-oxygen" on Fe-ZSM-5 zeolite, a surface oxygen species responsible for high reactivity in oxidation of methane and of benzene, has been investigated. We present from density-functional-theory (DFT) calculations how such a reactive surface species is generated upon decomposition of dinitrogen oxide (N2O) and propose a possible form of ``α-oxygen" on Fe-ZSM-5 zeolite. In the initial stages of the reactions, a complex involving an Fe(ON2) moiety is formed, followed by dissociation into an iron-oxo species and N2. The activation energy for the decomposition of N2O on a possible iron active site model of Fe-ZSM-5 zeolite is predicted to be 2.4 kcal mol-1 at the B3LYP level of theory. Therefore the decomposition of N2O is expected to take place easily at a coordinatively unsaturated iron active center supported on zeolite. The iron-oxo species thus formed should play an essential role in the direct hydroxylation of methane, benzene, and other hydrocarbons if it involves a coordinatively unsaturated iron. The oxygen exchange on the iron-oxo complex was also investigated. The activation energy for the oxygen exchange on the ``α-oxygen" is predicted to be 26.8 kcal mol-1. We propose that the bare FeO+ complex and the so-called ``α-oxygen" on Fe-ZSM-5 zeolite involve similar catalytic active centers responsible for similar catalytic functions for methane and benzene.
  • Keishi Ohara, Shin-ichi Nagaoka, Kazuo Mukai
    2000 Volume 73 Issue 1 Pages 37-42
    Published: 2000
    Released: October 31, 2001
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    The photosensitized reaction of maleimide (MI) with xanthone (Xn) in 2-propanol was investigated by the time-resolved EPR method. The emissive CIDEP spectrum observed in neat 2-propanol is predominantly assigned to two kinds of MI alkyl-type radicals. On the other hand, the absorptive spectrum of the MI anion radical has been newly observed in 2-propanol including hydrochloric acid. The addition effect of hydrochloric acid indicates the existence of two mechanisms for the photosensitization of MI by Xn. One is a typical triplet-triplet energy transfer followed by hydrogen abstraction by the triplet state of MI from the solvent. The other is an electron-transfer process to MI from the Xn ketyl radical produced primarily by a fast reaction of the triplet Xn with HCl. The spin-polarization transfer mechanism based on these photosensitization processes can successfully explain the present CIDEP results. The effect of water and the sensitizer dependence on the above reaction were also investigated.
  • Kazuchiyo Takaoka, Sigehiro Maeda, Hidetoshi Miura, Takao Otsuka, Kazu ...
    2000 Volume 73 Issue 1 Pages 43-51
    Published: 2000
    Released: October 31, 2001
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    Theoretical valence photoelectron and UV-visible absorption spectra of four stable conductive molecules (N, N-diphenyl-1,4-phenylenediamine (DPPD), p-quaterphenyl (PQP), 2, 3, 7, 8, 12, 13, 17, 18-octaethyl-21H, 23H-porphyrin (OEP), and 29H, 31H-phthalocyanine (PC)) have been obtained by semiempirical HAM/3 and ZINDO MO calculations, respectively. The Al K α photoelectron spectra were simulated using Gaussian lineshape functions of an approximate linewidth 0.10 Ek (Ek = Ek - WD), where Ek is the vertical ionization potential (VIP) of each MO and WD is a shift to account for sample work function and other energy effects, as stated in previous studies. The theoretical valence spectra of the four conductive compounds are in good accordance with the observed ones. The theoretical UV-visible absorption curves of DPPD, PQP, OEP, and PC were obtained after AM1 calculations with COSMO option to reflect solvent effects. The absorption curves as simulated with Gaussian lineshape functions of a constant linewidth of 0.003 eV. Correspond well to the observed spectra. For PC, the simulated spectrum which consists of 0.5 inner protonation (IP) and 0.5 outer protonation (OP) types for PC-ring shows much better agreement with the experimental spectrum in H2SO4 than the spectrum of either IP or OP type alone.
  • Tatsuo Oguchi, Akira Miyoshi, Mitsuo Koshi, Hiroyuki Matsui
    2000 Volume 73 Issue 1 Pages 53-60
    Published: 2000
    Released: October 31, 2001
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    The unimolecular decomposition of methoxy radicals, CH3O + M → CH2O + H + M (1a), has been directly studied by laser photolysis-laser-induced fluorescence method in the temperature range 610—740 K. Nearly linear pressure dependence of the first-order decay rate was observed in the investigated pressure range (100—450 Torr), and the second-order rate constants were derived for He and N2 buffer gases as: k0(He) = 2.8 × 10-9 exp (-84.3 kJ mol-1/RT) cm3 molecule-1 s-1 and k0(N2) = 4.3 × 10-9 exp (-84.1 kJ mol-1/RT) cm3 molecule-1 s-1, respectively. An RRKM calculation with a semiclassical one-dimensional tunneling treatment showed that the tunneling effect is essentially important in the present experimental conditions. The calculation indicates a non-linear pressure dependence of the rate constant even in the classical low-pressure limiting conditions, which is consistent with the experimental observations. The RRKM model (with threshold energy = 101.7 kJ mol-1) derived by the best fit to the experimental results is in good agreement with the theoretical investigations and the microcanonical rate constants measured by the stimulated emission pumping method.
  • Megumi Kameya, Toshio Naito, Tamotsu Inabe
    2000 Volume 73 Issue 1 Pages 61-65
    Published: 2000
    Released: October 31, 2001
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    A fused polycyclic aromatic compound, rubrene (RB), has been found to form a charge-transfer compound with iodine with the stoichiometry of RB·I9. The crystal is monoclinic, space group C2/c, a = 14.482(4), b = 16.676(8), c = 19.985(4) Å, β = 106.90(2)°, V = 4618(2) Å3, and Z = 4. In this crystal, a unique branched crank-shaped one-dimensional (I9-) polyiodide chain is formed. RB is surrounded by the polyiodide, and its cation radical state, which is unstable under normal conditions, is stabilized. The formation of the RB cation radical has been confirmed by IR, VIS-NIR, and EPR spectroscopies. The magnetic susceptibility measurement has indicated the existence of superexchange interactions through the polyiodide.
  • Yuji Miyazaki, Tetsuya Matsumoto, Takayuki Ishida, Takashi Nogami, Mic ...
    2000 Volume 73 Issue 1 Pages 67-71
    Published: 2000
    Released: October 31, 2001
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    Heat capacities of the organic free radical ferromagnet, 4-(4-chlorobenzylideneamino)-2,2,6,6-tetramethylpiperidin-1-oxyl (CATMP) have been measured in the temperature range between 0.1 and 311 K. A ferromagnetic phase transition was observed at 0.28 K and a heat capacity hump was found above the transition temperature. This hump is due to the short-range order characteristic of low-dimensional magnetic spin systems. The enthalpy and entropy gains due to the ferromagnetic phase transition were estimated to be 4.06 J mol-1 and 5.71 J K-1 mol-1, respectively. This entropy agrees well with the theoretical value Rln 2 ( = 5.76 J K-1 mol-1) expected for the magnetic entropy of a spin system with the spin quantum number S = 1/2, where R is the gas constant. The heat capacity hump above the transition temperature is well accounted for in terms of the S = 1/2 two-dimensional ferromagnetic Heisenberg model of square lattice with the intralayer exchange interaction J/kB = 0.42 K, where the spin Hamiltonian H = -2JSi·Sj is adopted and kB stands for the Boltzmann constant. The analysis of the magnetic heat capacities below the transition temperature on the basis of the spin wave theory clarified that the magnetic system settles down in three-dimensional ferromagnetic order below the transition temperature with the interlayer exchange interaction J/kB = 0.024 K.
  • Akira Hanaki, Tomoyuki Kinoshita, Toshihiko Ozawa
    2000 Volume 73 Issue 1 Pages 73-80
    Published: 2000
    Released: October 31, 2001
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    Catecholamines including epinephrine, norepinephrine, dopamine, and dihydroxyphenylalanine accelerated copper-catalyzed oxidation of cysteine under aerobic conditions, while they had no effect under anaerobic conditions. The efficiency of the catecholamines was arranged in the decreasing order as follows; epinephrine ≈ norepinephrine ≥ dopamine > dihydroxyphenylalanine. On the contrary, phenolic amines such as tyramine and tyrosine neither accelerate nor inhibit the autoxidation. The reaction can be elucidated by a ``sequentical mechanism'' which is composed of Eqs. I, II, III, IV, V, and VI :

    where L is glycylglycine used as the buffer, and CyS- and Cat- denote cysteinate and catecholamine ions, respectively. The reactions (IV), (V), or both are considered to be rate-determining. The optimum pH for the autoxidation was observed at pH 7.5—7.6, and below pH 7.2 reaction (V) does not participate in the autoxidation system.

  • Shuji Emori, Michio Nakashima, Wasuke Mori
    2000 Volume 73 Issue 1 Pages 81-84
    Published: 2000
    Released: October 31, 2001
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    Dinuclear compounds (R4N)2[Co2Cl4(4-XC6H4O)2] (X = H, CH3; R = CH3, C2H5) were prepared, and their temperature-variable magnetic susceptibilities were determined to evaluate the exchange-coupling strength's between the cobalt(II) ions. The coupling strength of (Et4N)2[Co2Cl4(4-CH3C6H4O)2] was considered in terms of its structural parameters and the electronic effects of the methyl substituent. Such magneto-structural correlations, together with those for copper(II), nickel(II), and iron(II) systems, confirm that the exchange couplings in phenoxo-bridged metal(II) compounds are affected concurrently by the s/p character of the hybrid orbitals on the bridging oxygen atom, by the electronic effects of the substituents on the aromatic ring, by the ionic radius and acidity of the metal(II) ion, as well as by the number of unpaired electrons and d character of the hybrid orbitals on the metal(II) ion.
  • Masao Mukaida, Yoshinobu Sato, Hideji Kato, Mami Mori, Dai Ooyama, Hir ...
    2000 Volume 73 Issue 1 Pages 85-95
    Published: 2000
    Released: October 31, 2001
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    Degradation sequences of cis-[Ru(NO·)X(bpy)2]n+ (X = ONO2, OCHO, OCOMe, NO2, Cl for n = 1; X = CH3CN, H2O for n = 2) ({RuNO}7-type), a one-electron reduction species of {RuNO}6-type complexes, were investigated in CH3CN by monitoring using electrochemical techniques (both cyclic and hydrodynamic voltammetries). The results show that an oxygen transfer occurs effectively at the nitrosyl site of cis-[Ru(NO·)X(bpy)2]n+ (X = ONO2 for n = 1, X = CH3CN, H2O for n = 2) to give identical nitro species, cis-[Ru(NO2)(CH3CN)(bpy)2]+. The extent that the nitrosyl-to-nitro conversion proceeded, however, differs depending on the X ligands; X = CH3CN and H2O complexes gave the nitro species in almost 40% yield, while X = ONO2 complex afforded nearly 80%. The monitoring results of the degradation sequences, along with the differences in yields, suggest that different processes are operating separately in the oxygen-transfer reaction. We propose some possible processes for both reactions, although a further investigation is needed for a detailed explanation.
  • Masafumi Goto, Takashi Matsumoto, Masamitsu Sumimoto, Hiromasa Kurosak ...
    2000 Volume 73 Issue 1 Pages 97-105
    Published: 2000
    Released: October 31, 2001
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    Square-planar complexes with the formula [Pt(L1)(L2)](NO3)2·nH2O, where L1 is bipyridine (bpy) and L2 is N-benzyl-1,2-ethanediamine (Been) (1) (n = 0), N-(1-naphthyl)methyl-1,2-ethanediamine (Npen) (2) (n = 2), and N-(9-anthryl)methyl-1,2-ethanediamine (Aten) (3) (n = 2), were prepared and X-ray crystal-structure determinations were carried out. The molecular structures of the complex cations revealed that the N-arylmethyl groups are forced to take pseudo axial dispositions due to an intramolecular repulsion from hydrogen atoms of bpy. The aromatic-aromatic interaction between the aromatic rings of ethanediamine derivatives and coordinated bpy caused 2 and 3 to take a conformation where the aromatic ring and bpy stack face-to-face to each other intramolecularly. An intermolecular aromatic-aromatic face-to-face interaction was also observed for 1, 2, and 3 in the crystals. The latter interaction occurs between bpy and the aryl substituent, except for 1. For D2O solutions of 1 through 3, significant upfield shifts due to the intramolecular stacking were observed in the 1H NMR spectra for the protons on the half ring of bipyridine, depending on the size of the aromatic ring. The crystal data of 1: monoclinic, P21/c, a = 9.884(2), b = 24.717(2), c = 9.560(5) Å, β = 113.83(3)°, Z = 4, and R = 0.029. 2: monoclinic, Ia, a = 17.030(5), b = 10.461(4), c = 14.727(4) Å, β = 94.72°, Z = 4, and R = 0.023. 3: monoclinic, Pn, a = 10.471(2), b = 8.844(5), c = 15.332(3) Å, β = 98.61(2)°, Z = 2, and R = 0.034.
  • Tetsuyoshi Naito, Hiromichi Yamada, Hiroko Wada
    2000 Volume 73 Issue 1 Pages 107-113
    Published: 2000
    Released: October 31, 2001
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    The solvent extraction of copper(II) with aliphatic carboxylic acids (CH3(CH2)nCOOH : n = 2—7) in alcohols (CH3(CH2)nOH : n = 4—7) was carried out at 25 °C and an aqueous ionic strength of 0.1 mol dm-3 (NaClO4). Each extraction equilibrium for these systems was determined in detail by a slope analysis and a curve-fitting method. In all of the extraction systems, except for butanoic acid ones, copper(II) carboxylates were found to be extracted as monomeric and dimeric species: CuA2, Cu2A4, and Cu2A4(HA)2. The dimerization and the adduct formation constants of copper(II) carboxylates in the organic phase were estimated. The dimerization and the adduct formation constants in the organic phase were found to be dependent on the chain length of the acids and alcohols, although the extraction constant of CuA2 were found to be independent of their chain length.
  • Makoto Watanabe, Masami Watanabe, Noriaki Narita, Makoto Sakurai, Hiro ...
    2000 Volume 73 Issue 1 Pages 115-119
    Published: 2000
    Released: October 31, 2001
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    Ammonium polyphosphate (APP) form II was prepared by heating of a mixture of ammonium orthophosphates (triammonium, diammonium, and monoammonium orthophosphates) and urea at 280 to 300 °C under wet ammonia, which was made by passing air through 3 to 5% aqueous ammonia. The following reaction process is proposed:

    Ammonium orthophosphate → APP form I → Amorphous APP → APP form II.

    The addition of APP form II shortened the preparation time significantly. A wider range of concentrations (1 to 8%) of aqueous ammonia was available to prepare APP form II. The average particle size of the obtained APP form II was larger than 5 μm.

  • Akihide Itoh, Kosuke Iwata, Koichi Chiba, Hiroki Haraguchi
    2000 Volume 73 Issue 1 Pages 121-127
    Published: 2000
    Released: October 31, 2001
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    The chemical stability of large organic molecule-metal complexes (LOMMCs) dissolved in pond water were investigated by a hyphenated system of size exclusion chromatography/UV absorption detection/inductively coupled plasma mass spectrometry (SEC/UV/ICP-MS) after ultrafiltration using a filter with a molecular permeation limit larger than 10000 Da. LOMMCs dissolved in the preconcentrated pond water sample were observed at the retention times corresponding to molecular weights larger than 300000 Da (Peak I) and that of 10000—50000 Da (Peak II) in the chromatograms measured by UV absorption and ICP-MS. When the pH of the sample solution was varied from 7.0 to 0.5 by adding the HNO3 solution, the peak intensities of both Peak I and Peak II in these chromatograms decreased with the decrease in pH of the sample solution. These results indicate that LOMMCs were decomposed by addition of HNO3. Peak I was rapidly decomposed below pH 4, while Peak II was gradually decomposed over the pH range from 7.0 to 0.5. The decomposition curve of Peak I was similar to the solubility characteristics of hydroxides of Fe and Al. On the other hand, that of Peak II suggested the dissociations of metal complexes (Cu and Zn) with some biogenic organic molecules. It was concluded from these results that some colloidal particles of hydroxides of Fe and Al may be core materials of LOMMCs for Peak I, while some metal complexes with biogenic protein-like compounds may be LOMMCs for Peak II. The possible models for LOMMCs in pond water were proposed as ``a string-ball model'', which might interpret as the removal and preservation mechanisms for trace elements in natural water.
  • Yasumasa Takenaka, Kohtaro Osakada
    2000 Volume 73 Issue 1 Pages 129-130
    Published: 2000
    Released: October 31, 2001
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    4-(N,N-Dimethylamino)pyridine (dmap) reacts with [{RhCl(nbd)}2] to give [RhCl(nbd)(dmap)] (1), which was characterized by X-ray crystallography and NMR spectroscopy. The crystal structure and dynamic behavior of the molecule in solution are compared with those of [RhCl(nbd)(PPh3)] (2).
  • Masaharu Tsuji, Takeshi Arikawa, Yukio Nishimura
    2000 Volume 73 Issue 1 Pages 131-145
    Published: 2000
    Released: October 31, 2001
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    The gas-phase ion-molecule reactions of CH5+, C2H5+, and C3H5+ with four monosubstituted benzenes carrying a hydroxy group in the substituent [PhX : X = OH, CH2OH, CH2CH2OH, and CH(OH)CH3] have been studied under a reactant-ion selective chemical ionization mode of an ion-trap type of GC/MS. The major product channel for PhOH is non-dissociative proton transfer leading to (M+H)+ ions, while that for the other three reagents is dissociative proton transfer leading to (M + H-H2O)+ ions in most cases. Small amounts of dissociative alkylation channels are found in some reactions with C2H5+ and C3H5+. The reaction mechanism is discussed based on the dependence of product-ion distributions on the reaction time and semi-empirical calculations of the energies of intermediates and products.
  • Makio Tamura, Akihiko Ueno
    2000 Volume 73 Issue 1 Pages 147-154
    Published: 2000
    Released: October 31, 2001
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    We constructed a polyrotaxane (1) composed of about 15 α-cyclodextrins, each bearing roughly two naphthalene units and a polyethylene glycol (PEG) as a threading chain with adamantane groups at both ends. The product was characterized by 1H NMR, 13C NMR, and absorption spectroscopies. We observed that photoenergy transfer occurs from the naphthalene units of 1 to 5-dimethylamino-1-naphthalenesulfonyl (dansyl) of dansyl modified β-cyclodextrin (Dnsβ-CD) when Dnsβ-CD forms a complex with each terminal adamantane moiety of the polyrotaxane. This energy transfer was reduced by the addition of adamantanol, which acts as a competitive binder for Dnsβ-CD.
  • Kentaro Okuma, Kyoko Shiki, Shinya Sonoda, Yuji Koga, Kosei Shioji, Ts ...
    2000 Volume 73 Issue 1 Pages 155-161
    Published: 2000
    Released: October 31, 2001
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    The reaction of thiobenzophenones (1) with phenyl[2-(trimethylsilyl)phenyl]iodonium trifluoromethanesulfonate (4) in the presence of tetrabutylammonium fluoride afforded the corresponding [4+2] cycloadducts, which are the first examples of thiobenzophenone-benzyne adducts. The reaction of thiopivalophenone (6) with benzyne prepared from 4 and tetrabutylammonium fluoride at room temperature gave [2+2] cycloadducts (7). When the reaction was carried out in refluxing dichloromethane, a mixture of 7 and [4+2] cycloadducts (13) was obtained.
  • Hiroshi Hinou, Atsusi Umino, Koji Matsuoka, Daiyo Terunuma, Shunya Tak ...
    2000 Volume 73 Issue 1 Pages 163-171
    Published: 2000
    Released: October 31, 2001
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    With interest in clustering bioactive chitooligosaccharides, a pair of amphiphilic derivatives of around DP (degree of polymerization) 6, which has been considered to be the minimum molecular length for some kinds of bioactivity, was synthesized. Homologous derivatives of chitopentaose and chitoheptaose carrying tetradecanoyl and tetradecyloxy groups at the NH and C-1 of the reducing ends, respectively, were actually obtained using a 1,6-anhydro-2-azido-2-deoxy-β-D-glucopyranose derivative as the terminal precursor and a chitobiose derivative as the elongation unit. Micelle formation of both derivatives was assumed from the results obtained by dye solubilization tests.
  • Shinkiti Koto, Motoko Hirooka, Kazuo Yago, Mitsuo Komiya, Toshio Shimi ...
    2000 Volume 73 Issue 1 Pages 173-183
    Published: 2000
    Released: October 31, 2001
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    Four tri-O-benzyl derivatives of 2-deoxy-2-(2,4-dinitroanilino)-D-glucopyranose were synthesized. Glycosylation using 3,4,6-tri-O-benzyl-2-deoxy-2-(2,4-dinitroanilino)-D-glucopyranose as glycosyl donor and a reagent mixture of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine produced β-glycosides with complete selectivity. Starting from benzyl 3,6-di-O-benzyl-2-deoxy-2-(2,4-dinitroanilino)-β-D-glucopyranoside as acceptor, O-α-D-galactopyranosyl-(1→4)-O-β-D-galactopyranosyl-(1→4)-2-acetamido-2-deoxy-D-glucopyranose, the human blood-group P1-antigenic determinant, was synthesized.
  • Koji Yano, Mitsunobu Osatani, Keita Tani, Tomohiro Adachi, Koji Yamamo ...
    2000 Volume 73 Issue 1 Pages 185-189
    Published: 2000
    Released: October 31, 2001
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    The syntheses of the title compounds are described. The unusually strained structures were supported by their 1H NMR spectra, electronic spectra, and X-ray crystallographic analyses.
  • Toshiya Sagisaka, Yasushi Yokoyama
    2000 Volume 73 Issue 1 Pages 191-196
    Published: 2000
    Released: October 31, 2001
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    When an enantiomer of resolved indolylfulgide (1) or either of the (R)-binaphthol-condensed indolylfulgides (2, 3) was mixed with a nematic liquid crystal (5CB), the cholesteric phase was induced. Their cholesteric pitches were reversibly changed by photoirradiation. Whereas the twisting ability of the cholesteric pitch (βM) was larger for the colorless form than for the colored form in the case of 1, it was larger for the colored form than for the colorless form in the cases of 2 and 3. In addition, βM of 1 is generally smaller than that of 2 and 3. These phenomena were explained in terms of the helical conformation of the hexatriene moiety of fulgides and the chirality of the binaphthol moiety.
    The cholesteric sense of a fulgide-doped liquid crystal was changed between plus and minus reversibly by the pre-doping of the chiral formaldehyde acetal of 1,1-bi-2-naphthol ((S)-4).
  • Toru Kawakami, Koki Hasegawa, Saburo Aimoto
    2000 Volume 73 Issue 1 Pages 197-203
    Published: 2000
    Released: October 31, 2001
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    A method for the synthesis of phosphorylated polypeptides was investigated through the synthesis of the phosphorylated cAMP response element binding protein 1 (19-106) amide, [Thr(PO3H2)69,71]-CRE BP1(19-106)-NH2, as a model compound. Three partially protected peptide segments: Boc-[Lys(Boc)23,46,48,54, Cys(Acm)27,32]-CRE BP1(19-56)-SCH2CH2CO-β-Ala-NH2, Fmoc-[Thr(PO3H2)69,71, Lys(Boc)77, Cys(Acm)79]-CRE BP1(57-83)-SCH2CH2CO-β-Ala-NH2, and [Lys(Boc)97,98,105,106]-CRE BP1(84-106)-NH2, were prepared by the Boc solid-phase method and were used as building blocks. The segment condensations were carried out sequentially by a thioester method in the presence of a silver compound, HOObt, and DIEA. The desired product was obtained in 19% yield, based on the C-terminal building block, after removal of all the protecting groups on the peptide. These results indicate that the thioester method is quite useful for the preparation of phosphorylated polypeptide even if it contains cysteine residues. One thing which remains to be improved is the efficiency of the method for the preparation of partially protected peptide thioesters, which contain phosphorylated amino acid residues.
  • Shinji Toyota, Takao Yamamori, Mitsuhiro Asakura, Michinori Oki
    2000 Volume 73 Issue 1 Pages 205-213
    Published: 2000
    Released: October 31, 2001
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    The substituent effect on the rotational barriers of acetylenic to tetrahedral C-C bonds was studied for the title compounds carrying Me or OMe substituents at the 1,4-positions in the 9-triptycyl groups. These compounds were prepared by use of the Diels-Alder and the Sonogashira reactions from a 9-ethynylanthracene derivative. The kinetic parameters were determined by the total lineshape analysis of the signals observed by the variable temperature 1H NMR for five compounds. The rotational barriers are in the range of 9—15 kcal mol-1, and are enhanced as the steric size of the substituents is increased (H < OMe < Me). This substituent effect is attributed to the destabilization of the transition state of the rotation process, where the two triptycyl groups are almost eclipsed about the central axis, by the steric interactions between the peri substituents. The acetylenic carbons are significantly deformed from the linear geometry in the X-ray structure of the tetramethyl compound. The substituent effect on the rotamer population is also discussed with the aid of the MM calculation.
  • Masafumi Unno, Akiko Suto, Keisuke Takada, Hideyuki Matsumoto
    2000 Volume 73 Issue 1 Pages 215-220
    Published: 2000
    Released: October 31, 2001
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    The versatility of cis,cis,cis-1,3,5,7-tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane (1) as a precursor of cage and ladder siloxanes is presented. Compound 1 reacted with 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane in pyridine to give 1,3,5,5,7,7,9,11,13,13,15,15-cis-cisoid-cis-dodecaisopropyltricyclo[9.5.1.13,9]octasiloxane (2) in 20% yield. The reaction proceeded with retention of the configuration of the silicon atoms, and only syn-type isomer was obtained. The reaction of 1 with 1,1,3,3-tetrachloro-1,3-diisopropyldisiloxane in pyridine produced hexakis(isopropylsilsesquioxane) (T6) (3) in 25% yield. Treatment of 1 with dicyclohexylcarbodiimide (DCC) as dehydrating reagent led to the formation of octakis(isopropylsilsesquioxane) (T8) (4) in 45% yield. The crystal structures of 2, 3, and 4 are reported.
  • Kouji Iida, Nobuyasu Ohya, Ayumi Kashiwada, Mamoru Mimuro, Mamoru Nang ...
    2000 Volume 73 Issue 1 Pages 221-229
    Published: 2000
    Released: October 31, 2001
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    The linear dichroism (LD) spectra of the light-harvesting polypeptide (LH)/bacteriochlorophyll (BChl a) complex, isolated from photosynthetic bacteria, Rhodospirillum rubrum, were measured to provide insight into the pigment orientation in the LH/BChl a complex. The LD spectrum for the Qy band of BChl a in the complex in a squeezed polyacrylamide gel was positive, while that for the Qx band was negative, indicating that the dipole moment of the Qy band was membrane-parallel while that of the Qx band was membrane-perpendicular. The anisotropy ratio, the LD/A value for the Qy transition of BChl a in the complex, was 0.18 ± 0.02 at a 0.5 compression-ratio, consistent with that for the Qy band of a special pair of BChl a in the reaction center (RC) complex isolated from R. rubrum. This result implies that the orientation of the Qy band in the LH/BChl a complex is perpendicular for the transmembrane axis of the LH in the complex as well as that of the special pair of BChl a in the RC. Furthermore, the LD/A spectrum for the Qy band of BChl a in the LH/BChl a complex indicated that the Qy band was geometrically homogeneous in the direction to the transmembrane axis in the complex.
  • Hiroyuki Nakamura, Masaru Fujiwara, Yoshinori Yamamoto
    2000 Volume 73 Issue 1 Pages 231-235
    Published: 2000
    Released: October 31, 2001
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    Enantiomerically pure L-BPA (4-borono-L-phenylalanine) was synthesized from L-tyrosine or 4-iodo-L-phenylalanine derivatives using the palladium-catalyzed cross-coupling reaction of pinacolborane (2,3-dimethyl-2,3-butanediolatoboron). Cbz-Tyr(Nf)-OBzl (2b) underwent the cross-coupling reaction with pinacolborane (1) in the presence of [PdCl2(PPh3)2] catalyst to give N-benzyloxycarbonyl-4-(2,3-dimethyl-2,3-butanediolatoboryl)-L-phenylalanine benzyl ester (3a) in 58% yield. The reaction of the 4-iodo-L-phenylalanine derivatives, such as N-benzyloxycarbonyl-4-iodo-L-phenylalanine benzyl ester (2c), N,N-dibenzyl-4-iodo-L-phenylalanine benzyl ester (2d), (4S)-3-benzyloxycarbonyl-4-(4-iodobenzyl)-5-oxazolidinone (2e), and (4S)-3-t-butyloxycarbonyl-4-(4-iodobenzyl)-5-oxazolidinone (2f), with 1 proceeded very smoothly in the presence of [PdCl2(dppf)] catalyst, giving N-benzyloxycarbonyl-4-(2,3-dimethyl-2,3-butanediolatoboryl)-L-phenylalanine benzyl ester (3a), N,N-dibenzyl-4-(2,3-dimethyl-2,3-butanediolatoboryl)-L-phenylalanine benzyl ester (3b), (4S)-3-benzyloxycarbonyl-4-[4-(2,3-dimethyl-2,3-butanediolatoboryl)benzyl]-5-oxazolidinone (3c), and (4S)-3-butyloxycarbonyl-4-[4-(2,3-dimethyl-2,3-butanediolatoboryl)benzyl]-5-oxazolidinone (3d), respectively, in high yields. Deprotection of 3ad gave enantiomerically pure L-BPA in high total yields.
  • Yasuhisa Senda, Nobuhito Kikuchi, Ayuko Inui, Hiroki Itoh
    2000 Volume 73 Issue 1 Pages 237-242
    Published: 2000
    Released: October 31, 2001
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    A significant directive effect of the 2-axial hydroxy group appeared in the LiAlH4, NaBH4, and Zn(BH4)2 reduction of cyclohexanone, while the 3-axial hydroxy group exhibited a steric hindrance. The distance between the carbonyl carbon and the hydroxy group which interacts with the hydride reagent is mainly responsible for such a difference. In the reduction of Na[B(OAc)3H], both the 2- and 3-axial hydroxycyclohexanones exclusively gave the products which were obtained by the hydride approaching from the side of the hydroxy group. The key point of this stereoselectivity is the formation of Na[B(OAc)2(OR)H], which is far more reactive than the parent hydride, by exchanging the acetate ion with the alkoxide.
  • Mitsuru Watanabe, Seiji Suga, Jun-ichi Yoshida
    2000 Volume 73 Issue 1 Pages 243-247
    Published: 2000
    Released: October 31, 2001
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    Organoheteroatom compounds having a 2-(2-pyridyl)ethyl group were synthesized and their oxidation potentials were determined by rotating disk electrode voltammetry. The oxidation potentials were found to be less positive than those of the corresponding compounds having a phenyl group in place of the pyridyl group. The dynamic coordination of the pyridyl group to the heteroatom, which stabilizes the cation radical intermediate, seems to be responsible for facilitating the electron transfer. The magnitude of the intramolecular assistance increases along with an increase in the oxidation potential of the parent compounds. This tendency can be explained in terms of the energy match between the nonbonding p orbital of the pyridyl nitrogen and the HOMO of the parent heteroatom compound.
  • Yuefa Gong, Katsuya Kato, Hiroshi Kimoto
    2000 Volume 73 Issue 1 Pages 249-250
    Published: 2000
    Released: October 31, 2001
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    A number of α-(trifluoromethyl)heteroarylmethanols 2ac are conveniently obtained in good yields by substitution of pyrole, furan, and thiophene with trifluoroacetaldehyde ethyl hemiacetal (TFAE); 2b and 2c are formed only in the presence of a catalyst such as ZnCl2. Analogous methanols 8a and 8b are also prepared by catalytic substitution of uracils with TFAE in moderate yields.
  • Hui-hui Li, Satoshi Inoue, Daisuke Ueda, Ken-ichi Machida, Gin-ya Adac ...
    2000 Volume 73 Issue 1 Pages 251-258
    Published: 2000
    Released: October 31, 2001
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    Lanthanide complexes, [Eu(phen)2]Cl3 and [Tb(bpy)2]Cl3, were doped into organically modified silicate (ORMOSIL) matrices over a wide range of composition. The features and luminescence behavior of the resultant composite products were strongly dependent on the matrix composition. Transparent ORMOSIL composite phosphor disks were obtained under the optimized complex concentration and matrix composition, as well as with careful control of the drying process. Luminescence property varieties of the composites based on various matrix compositions were studied and interpreted from the viewpoint of local chemical environment around the doped complex molecules. Those for composite phosphors incorporated with [Eu(phen)2]Cl3 were additionally characterized by the 5D0-7F2 to 5D0-7F1 emission intensity ratio. Illustrative models of the lanthanide complex-containing sol-gel derived composites were proposed.
  • Hiroaki Shitara, Yoshio Aoki, Takuji Hirose, Hiroyuki Nohira
    2000 Volume 73 Issue 1 Pages 259-265
    Published: 2000
    Released: October 31, 2001
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    Chiral 2-methylchroman-2-carboxylic acid derivatives were prepared as new chiral dopants for nematic liquid crystals. The starting material, optically active 6-benzyloxy-2-methylchroman-2-carboxylic acid, was newly synthesized as a rigid core structure and resolved by a diastereomeric salt formation method. Its absolute configuration was determined by comparing its circular dichroism spectrum with that of the commercially available (S)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid derivative. The helical twisting power of the new dopants was determined and the relationship between their functional groups and flexible terminal structures was studied.
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