Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
71 巻 , 9 号
選択された号の論文の30件中1~30を表示しています
  • Hiroshi Okamoto, Masahiro Yamashita
    1998 年 71 巻 9 号 p. 2023-2039
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    We report the photogeneration of solitons and polarons in the quasi-one-dimensional (1-D) halogen (X)-bridged metal (M) compounds (simply abbreviated as the MX chain compounds). The most significant feature of this system is the remarkable tunability of the charge density wave (CDW) ground states. By substituting the metals (M = Pt, Pd, and Ni), the bridging halogens (X = Cl, Br, and I), the ligand molecules and the counter anions surrounding the 1-D chains, the amplitude of CDW, the optical gap energy, and the degeneracy of CDW can be widely controlled. On the basis of these controls, we have investigated the nature of photoexcited states. By comparing the results of photoinduced absorption (PA), ESR and photoinduced ESR measurements in the degenerate CDW states with those in the non-degenerate CDW states, we clearly characterized the photoinduced gap states as solitons and polarons. In the compounds having relatively large optical gap energies (ECT), spin-solitons and polarons are photogenerated. From a comparison of the excitation profiles of the PA signals with those of the luminescence of the self-trapped exciton (STE), it was demonstrated that the luminescence process strongly competes with the dissociation to spin–soliton pairs. An analysis of the temperature dependence of the luminescence decay time revealed that the conversion from an STE to a solitonic state occurs through a finite potential barrier, the magnitude of which depends on degeneracy of CDW. With decrease of ECT, the nature of the photoexcited states changes considerably; photogenerations of charged-solitons are observed instead of spin–solitons and the STE luminescence is remarkably quenched. While referring to the theoretical expectations based upon the Peierls–Hubbard model, we will discuss the overall view of the relaxation process of the photoexcited states related to solitons, polarons, and excitons in the MX compounds.
  • Atsuyoshi Ohno
    1998 年 71 巻 9 号 p. 2041-2050
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Stereoselectivity controlled by an electronic effect but not by a steric effect is presented. A modern concept of stereochemistry is proposed where stereochemistry is controlled by acceleration of the reaction instead of deceleration, as has been proposed based on classical concept. The mechanism of (net) hydride transfer from a dihydronicotinamide adenine dinucleotide (NADH)/dihydronicotinamide adenine dinucleotide phosphate (NADPH) analogue to certain oxidizing agents is discussed in relation to this modern stereochemistry concept. The reaction involves a preassociation complex where the stereochemistry of the reaction is defined. Only a complex that has appropriate intermolecular arrangement can proceed to the transition state. The difference in free energy between the two stereoisomers of the preassociation complex contributes to almost all of the difference in the free energy of activation for the stereoisomers in the transition state, then to the ratio of stereoisomers in the product. Thus, the transition state does not participate in determining the stereochemistry of the reaction.
    Similarities between the present and enzymatic reactions from the viewpoint of the reaction scheme are also suggested.
  • Rong-Shun Zhu, Ke-Li Han, Jian-Hua Huang, Ji-Ping Zhan, Guo-Zhong He
    1998 年 71 巻 9 号 p. 2051-2054
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The X1Σ ground state and the low-lying 1,3Σ, 1,3Π excited states of the Ca–Ar and Sr–Ar systems have been studied using pseudopotentials at MCSCF(CASSCF)-SDCI level. The results indicate that the 1,3Σ excited states are essentially repulsive, but the X1Σ ground state and the 1,3Π excited states have shallow potential minima at large equilibrium distance (Re) values. Spectroscopic constants of the X1Σ ground state and the 1,3Π excited states have been calculated and compared to those obtained by experiment.
  • Pandharinath S. Nikam, Arun B. Sawant
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2055-2061
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The viscosity measurements for some symmetrical tetraalkyl ammonium bromide (R4NBr, R = CH3 to C5H11) KCl, and KBr solutions in acetonitrile (ACN) + water mixtures containing 0, 10, 30, 50, 70, 90, and 100 mass% of ACN at 303.15 K have been performed. The Jones–Dole equation was used for the analysis of viscosity data of these salts. The viscosity B-coefficients in the entire range of ACN+water mixtures were obtained from the computerized least-squares method. The experimental criterion B(K+) = B(Cl) = (1/2)B(KCl) was applied in order to obtain the ionic B-coefficients. The B± coefficients are interpreted in terms of solvent structure and ion-solvent interactions in the solvents.
  • Kentaro Nakamura, Kazuo Eda, Noriyuki Sotani
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2063-2070
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Hydrogen molybdenum bronze, HxMoO3 (x = 0.25), was treated in vacuo, which was changed by four steps to form MoO3 and MoO2 through the Type-I and the MoO3-like structure with defects, such as an oxygen vacancy. The structural changes were studied by TG-DTA, XRD, ESR, and XANES. Type-I with a defect structure was effective for the isomerization of 1-butene.
  • Shinsaku Fujita
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2071-2080
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The maturity of a finite group G is defined by examining how a dominant class (Q-conjugacy class) corresponding to a cyclic subgroup H contains conjugacy classes. If the ingeter q = |NG(H)|/|CG(H)| (called the maturity discriminant) is less than an Euler function φ(|H|), the group |G| is concluded to be unmatured concerning H, where NG(H) and CG(H) respectively denote the normalizer and the centralizer of H within G. A matured representation defined for a matured or an unmatured group is subduced into cyclic subgroups to give the corresponding monomials, which are applied to the combinatorial enumeration of isomers.
  • Akinori Takahashi, Yohko F. Yano, Takao Iijima
    1998 年 71 巻 9 号 p. 2081-2086
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The structure of liquid chloroform has been investigated by energy-dispersive X-ray diffraction. For the stability of the sample thickness, even for a volatile liquid, a glass capillary tube has been used as a sample container. The intensity function has been accounted for by a bcc (body-centered cubic)-like local lattice structure model with a lattice constant of 6.24 Å. However, it has been necessary to replace a fraction (34%) of the nearest neighbors by super-near configurations in which molecules are rather tightly correlated. The correlation is, however, rapidly lost as the distance between molecules increases, and the long range structure is characterized by a large Prins parameter. The structure of liquid chloroform is much less ordered than that of carbon tetrachloride.
  • Kazunari Yoshizawa, Takashi Kato, Tokio Yamabe
    1998 年 71 巻 9 号 p. 2087-2095
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The role of second-order perturbations in interlayer interactions of two-dimensional electronic systems is examined from simple two-layer models. The preferred nuclear motions are discussed specifically for the preferred stacking of layers in graphite on the basis of transition-density analyses for extended systems. The well-known ABAB stacking of layers in neutral graphite and the AAAA stacking of layers in graphite intercalation compounds (GICs) such as C6Li and C8K complexes are proposed to be consequences of orbital interactions (near the Fermi level) between nearest neighbor layers. This paper raises doubts about a widely accepted belief that the interlayer interaction between graphite layers is of the van der Waals type.
  • Takashi Kawakami, Syusuke Yamanaka, Yu Takano, Yasunori Yoshioka, Kiza ...
    1998 年 71 巻 9 号 p. 2097-2108
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The electronic structures of linear magnetic clusters composed of eleven triplet methylenes, eleven quartet nitrogen atoms, and five triplet methylenes plus six quartet nitrogen atoms were investigated by the unrestricted Hartree–Fock (UHF), post UHF and their spin-projected wavefunctions in combination with the Heisenberg model. The effective exchange integrals (Jab) in the Heisenberg model were calculated by the difference between the total energies of the highest spin (HS) and lowest spin (LS) UHF-based wavefunctions of the clusters. The Jab values by the UHF-based and spin-polarized DFT methods were compared with those of the SO-Cl, MRSDCI, CASSCF, CASPT2, and MRMP2 calculations in the case of small linear clusters, such as a triplet methylene dimer. The spin-polarized density functional (BLYP and B3LYP) calculations followed by the size-consistent spin projection were carried out for dimer, trimer, and clusters with eleven magnetic sites to obtain the Jab values, since the DFT methods were heavily utilized in solid state physics. It was found that all of the methods, except for DFT, provide similar Jab values in the magnetic region of the dimer, where the interatomic distance is longer than 3.0 Å. However, the spin crossover from the LS state to the HS state occurs at a larger distance in the cases of MRSDCI and MRMP2. The spin projection for LS spin-polarized wavefunctions becomes less important in the case of long linear clusters, such as (CH2)11. The DFT results are generally biased to stabilize the low-spin states. The implications of the calculated results are discussed in relation to the molecular magnetisms in mesoscopic molecular aggregates.
  • Keiju Sawada, Tatsuo Kitamura, Yuji Ohashi, Nahoko Iimura, Hirotaka Hi ...
    1998 年 71 巻 9 号 p. 2109-2118
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The cationic surfactants such as hexadecyl-, tetradecyl-, dodecyl-, and decyltrimethylammonium bromides form complexes with a variety of aromatic compounds in aqueous solutions. Well-defined crystals were obtained if the aromatic compounds had hydrogen donor moieties. The structures of ten kinds of the complex crystals were analyzed by X-rays. All the crystal structures had a common pattern of complex formation, in which the aromatic compounds are sandwiched by the two alkyl chains of the surfactant molecules. There are two modes of stacking when the complexes with the common pattern are piled up to form the crystalline lattice. The common pattern of complex formation is responsible for the high viscoelasticity of the aqueous solutions containing cationic surfactants and aromatic compounds.
  • Akira Shiga, Akira Tsujiko, Shinji Yae, Yoshihiro Nakato
    1998 年 71 巻 9 号 p. 2119-2125
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Photoelectrochemical activity of nanocrystalline TiO2 film electrodes prepared by use of various TiO2 particles has been studied comparatively. It is confirmed that the photocurrent (or photoactivity) for anatase-type TiO2 is in general higher than that for the rutile-type. The photocurrent quantum yield (ηpc) for anatase-type TiO2 is nearly equal to that for rutile-type in long wavelengths but increases more and more with decreasing wavelength in contrast to the ηpc for rutile-type, and thus the ηpc for anatase-type becomes much higher than the ηpc for rutile-type in short wavelengths around 300 nm, indicating that the high photoactivity for anatase-type TiO2 is due to this high ηpc in short wavelengths. There are some discussions on the reasons for the high ηpc for anatase-type TiO2 in short wavelengths, including the possibility of contribution of hot electrons or holes in the TiO2 film.
  • Masanobu Watanabe, Masaru Sato, Akira Nagasawa, Izumi Motoyama, Toshio ...
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2127-2136
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The structures of ferroceno[1.1]ruthenocenophane-1,13-dione (1a) and related compounds have been analyzed by X-ray diffraction. The crystal form of 1a is orthorhombic, space group Pbc21, a = 6.0660(3), b = 13.371(1), c = 19.420(2) Å, V = 1575.1(2) Å3, and the final R = 0.043 and Rw = 0.054. The air-oxidation of ferroceno[1.1]ruthenocenophane (2a) in xylene at 400 K gives ferroceno[1.1]ruthenocenophane-1-one (3a), implying the oxidation of the methylene group to a carbonyl group. The crystal form of 3a is orthorhombic, space group Pbn21, a = 7.6460(7), b = 10.708(1), c = 19.587(2) Å, V = 1603.7(3) Å3, and the final R = 0.052 and Rw = 0.051. The same oxidation is found for [1.1]ferrocenophane (2b) giving [1.1]ferrocenophane-1-one (3b). The crystal form of 3b is orthorhombic, space group Pbnm, a = 7.5460(9), b = 10.6560(6), c = 19.8290(7) Å, V = 1594.4(2) Å3, and the final R = 0.070 and Rw = 0.077. All the structural data of 1a, 3a, and 3b showed their syn conformation about two bridging methylene groups and rigid structures caused by the good planarity of C5H4COC5H4 and C5H4CH2C5H4 planes. These rigid structural features give remarkable variable temperature NMR (VT-NMR) spectra caused by the appropriate rate constant of synasynb motion in solutions. The ΔG(Tc) values of the motion are estimated to be about 60 kJ mol−1, which is more than six times larger than those of 2a and 2b. The anti-form of ferrocenium[1.1]ruthenocenophane formulated as [FeIII(C5H4CH2C5H4)2RuII]PF6 (4) was prepared by the oxidation of the syn-form 2a in sulfuric acid containing NH4PF6. This is the first example of the oxidative occurrence of the conformational change from syn- to anti-form. The crystal form of 4 is triclinic, space group P1, a = 9.350(2), b = 10.777(3), c = 10.980(3) Å, α = 91.84(3)°, β = 96.66(2)°, γ = 111.12(2)°, V = 1021.8(5) Å3 and the final R = 0.044 and Rw = 0.048. The cation contains largely twisted C5H4CH2C5H4 plane (the twist angle, 34.1—38.5°) and largely tilted and rotated Cp-rings of the Ru(C5H4)2 moiety.
  • Shoji Tagashira, Yoshiko Murakami, Mituya Yano, Yoshiaki Sasaki
    1998 年 71 巻 9 号 p. 2137-2140
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    An aqueous solution containing surfactants exhibits the property of being separated into two phases due to a temperature change or an addition of salts. The extraction and stripping of copper(I) as a neocuproine complex were investigated between the anionic surfactant of sodium dodecylsulfate (SDS) and aqueous phases. When the surfactant was separated by the addition of NaCl, the copper complex was extracted into the SDS phase. The stripping of copper(I) into the aqueous phase was maintained by phase separation, which was achieved by cooling the solution. Since neocuproine is a highly specific chromogen for copper(I), iron(II) could not form a complex with neocuproine, and was scarcely extracted into the SDS phase. This selective extraction was applied to the separation of copper from iron and the determination of copper in steel samples by a spectrophotometric method and/or an atomic-absorption spectrometric method (AAS).
  • Akinobu Nasu, Koji Kato, Tatsuya Sekine
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2141-2148
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The solvent extraction of copper(I) and copper(II) from 1 mol dm−3 Na(X, NO3), where Xis Cl, Br, or I, as ion-pairs of anionic halide complexes with tetrabutylammonium ions (tba+) into chloroform was studied in the absence and presence of a reducing agent, ascorbic acid. The extraction of copper(II) with 2-thenoyltrifluoroacetone (Htta) in chloroform from these aqueous solutions was also studied. In the absence of ascorbic acid, the extraction of copper which was added as Cu2+ with tba+ was negligible from chloride and bromide solutions but tba+CuIII3 and (tba+)2CuIII42− were extracted from iodide solutions. In the presence of ascorbic acid, the extraction of tba+CuIX2 was found from all of these halide solutions. Only copper(II) was extracted with Htta from these solutions. The distribution ratio was lower when the halide concentration was higher due to formation of copper(II) complexes in the absence of ascorbic acid and it was much lower in the presence of this reducing agent due to formation of copper(I) complexes, which were stabler than the copper(II) complexes. From the extraction data with tba+ and with Htta, the formation constants of copper(I) and copper(II) halide complexes from Cu2+ in the aqueous phase as well as the extraction constants of certain complexes into the organic phase were determined. It was concluded that the dominant metal species in the aqueous phase was Cu2+ when the halide concentration was low even in the presence of the reducing agent and thus copper(I) anionic complexes were extracted into the organic phase and the molar ratio of copper(I) complex species to Cu2+ in the aqueous phase was higher at higher halide concentrations.
  • Byongjin Lee, Junko N. Kondo, Fumitaka Wakabayashi, Kazunari Domen
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2149-2152
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Quantitative analysis of the high-temperature behavior of the Brønsted acidic hydroxyl groups on H-ZSM-5 and H-mordenite zeolites was conducted by in situ IR spectroscopy. The integrated intensity of the Brønsted acidic hydroxyl band on H-ZSM-5 was decreased to 67% at 873 K compared with that at room temperature. This was considered to reflect the deprotonation of hydroxyls at high temperature. Attributing the decreased OH groups at high temperature region to the conversion to IR inactive dissociated species, we estimated the energy difference between the nondissociated and dissociated hydroxyls as 24 kJ mol−1 on H-ZSM-5.
  • Yoshitaro Miyashita, Narumi Sakagami, Yasunori Yamada, Takumi Konno, K ...
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2153-2160
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Novel dinuclear complexes, [M2(aet)4(cysta)]2+ (M = IrIII (1), RhIII (2); aet = NH2CH2CH2S, cysta = NH2CH2CH2SSCH2CH2NH2), were prepared by the oxidation reactions of fac(S)-[M(aet)3]. The crystal structures of the complexes were determined by X-ray diffractions: 1Cl2·4H2O, monoclinic, P21/a, a = 12.427(2), b = 8.879(1), c = 13.387(1) Å, β = 91.947(10)°, V = 1476.3(3) Å3, Z = 2, and R = 0.031; 2Cl2·2H2O, monoclinic, P21/c, a = 11.788(2), b = 8.485(1), c = 14.800(2) Å, β = 112.980(9)°, V = 1362.9(3) Å3, Z = 2, and R = 0.023. In the structures of 1 and 2, two octahedral fac(S)-[M(aet)3] units are linked by a coordinated disulfide bond. Their disulfide sulfur atoms are bound to the Ir and Rh atoms more strongly than to the Co atom. Both complexes 1 and 2 take only the ΔRΛS configuration of ten possible isomers. The electronic absorption, 13C NMR, and infrared spectra exhibit characteristic behavior in relation to the disulfide bond. 1 and 2 are fairly stable in water, and their structures in solid are retained in solution. The reduction or oxidation of the dinuclear complexes causes a cleavage of the disulfide bond to afford the mononuclear thiolato or sulfinato complexes. The properties of the present complexes are also discussed in comparison with those of the mononuclear and/or polynuclear complexes with the corresponding metal ions.
  • Masahiro Mikuriya, Xiao Jian, Shin-ichiro Ikemi, Takako Kawahashi, Hid ...
    1998 年 71 巻 9 号 p. 2161-2168
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Zinc(II) complexes with 2-[(2-aminoethyl)amino]ethanethiol (HL1), 2-[(3-aminopropyl)amino]ethanethiol (HL2), 2-[(2-pyridylmethyl)amino]ethanethiol (HL3), and 2-{[2-(2-pyridyl)ethyl]amino}ethanethiol (HL4), [Zn(L1)](ClO4) (1), [Zn{Zn(L1)2}2](ClO4)2 (2), [Zn(L2)](ClO4) (3), [Zn{Zn(L3)2}2](ClO4)2 (4), and [Zn3(L4)3](ClO4)3 (5), have been synthesized and characterized by measurements of the infrared and electronic spectra. The molecular structures of these complexes were determined by the single-crystal X-ray structure analysis. Complex 1 has a thiolato-bridged polymeric chain structure, in which each metal atom is essentially four-coordinated in a distorted tetrahedron. Complexes 2 and 4 have a thiolato-bridged trinuclear complex with a linear arrangement of three metal atoms. Complex 5 is a thiolato-bridged trinuclear complex displaying a six-membered ring of Zn3S3.
  • Habib Firouzabadi, Nasser Iranpoor, Mohammad Ali Zolfigol
    1998 年 71 巻 9 号 p. 2169-2173
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Fe(NO3)3·1.5N2O4 and Cu(NO3)2·N2O4 are efficient reagents for oxidative deprotection of various silyl and tetrahydropyranyl ethers, acetals, and thioacetals in aprotic organic solvents. Fe(NO3)3·1.5N2O4 is also able to perform the reactions efficiently in the absence of solvents at room temperature. Over-oxidation of the products has not been observed in these reactions. A synergic effect of N2O4 upon the oxidation abilities of metal nitrates is observed.
  • Ewa D. Raczynska, Masaaki Mishima, Mustanir
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2175-2179
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Proton-transfer reactions for N1,N1-dimethyl-N2-benzoylformamidine containing three basic sites, the carbonyl-O, imino-N, and amino-N atoms, have been studied by experimental (FT-ICR) and theoretical (ab initio) methods. The ICR study gave a GB of 225.5 kcal mol−1 for this compound. The empirical structure-basicity relationships predicted GB values of 224.8 and 212.8 kcal mol−1 for protonation at the imino-N and carbonyl-O atoms, respectively. The observed GB values is close to the value for the imino-N atom. Theoretical calculations (B3LYP/6-311+G(2d,p)//HF/6-31G(d)) also showed that protonation at the imino-N atom is preferred by 7 kcal mol−1 compared to protonation at the carbonyl-O atom.
  • Young Dae Gong, Hiroko Tanaka, Nobuharu Iwasawa, Koichi Narasaka
    1998 年 71 巻 9 号 p. 2181-2185
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Aromatic vinyl ethers and acetals underwent a novel addition-fragmentation reaction affording olefins and esters in the presence of a Lewis acid. This reaction was applied to intramolecular cyclization reaction, giving five or six membered ring compounds in good yields. Paracotoin, an intermediate in the biosynthesis of shikimic acid, was synthesized using this cyclization reaction as the key step.
  • Yasushi Kawai, Takashi Matsuo, Atsuyoshi Ohno
    1998 年 71 巻 9 号 p. 2187-2196
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The kinetics for the hydrolyses of p-nitrophenyl esters of acetic acid and certain amino acid derivatives mediated by α-chymotrypsin have been studied. The kinetics are a function of the medium viscosity, which indicate that the enzyme must change its conformation during the reaction. Detailed analysis of the dependence of kinetic rate constants on the medium viscosity has revealed that (1) the reaction is associated with the induced-fit conformational adjustment of the enzyme: When the enzyme-substrate (ES) complex is converted into the corresponding acyl enzyme, the conformation of the enzyme is changed in order to accommodate the acyl group in the pocket of the enzyme at an appropriate position. (2) The conformationally distorted α-chymotrypsin recovers its conformation when it releases the acid part of the substrate ester. (3) The formation of an ES complex is independent of any induced-fit movement. The induced-fit conformational adjustment of the enzyme plays a crucial role in its catalytic activity.
  • Taro Kimura, Masayuki Takeuchi, Seiji Shinkai
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2197-2204
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    A boronic-acid-appended amphiphile bearing an azobenzene chromophore at the chain center, N-[4-(dihydroxyboryl)benzyl]-N-(10-{4-[(4-dodecyloxyphenyl)azo)]phenoxy}decyl)-N,N-dimethylammonium bromide (4) was synthesized. In aqueous media, compound 4 formed a scarcely-oriented aggregate in the absence of saccharides, but in the presence of saccharides the boronic acid groups formed saccharide complexes and the resultant amphiphiles formed well-ordered aggregates. The ΔH value in DSC depended on the inherent structure of the added saccharides. Although D-glucose and methyl α-D-glucopyranoside could only form less ordered aggregates, D-fructose and D-xylose formed well-ordered aggregates. The saccharide complexes with 4 became CD-active with the appearance of exciton-coupling bands inherent to the saccharides. The CD band intensity was increased with increasing saccharide concentration but decreased by a further increase in the saccharide concentration. These results indicate that the reversible boronic acid–saccharide interaction is useful to induce the chirality in the ordered aggregate structure, where saccharides are used as a trigger for the chiral induction.
  • Shu-ichi Nakano, Naoki Sugimoto
    1998 年 71 巻 9 号 p. 2205-2210
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    A 24-mer peptide with L2 and helix G amino acids of E. coli RecA protein (Ac–Ile–Arg–Met–Lys–Ile–Gly–Val–Met–Phe–Gly–Asn–Pro–Glu–Thr–Thr–Thr–Gly–Gly–Asn–Ala–Leu–Lys–Phe–Tyr–NH2) showed a single-stranded DNA (ssDNA) binding property with a more than 1000 times affinity difference than for a double-stranded DNA. However, a truncated 15-mer peptide (sequence) showed no ssDNA binding activity. In the ssDNA binding, the 24-mer peptide changed its conformation with the perturbation of an α-helix structure. The ssDNA binding and the DNA discrimination property of this peptide were due to almost all L2 and helix G amino acids, respectively. This result useful to design synthetic peptides as functional materials for DNA recognition.
  • Masanobu Kojima, Akito Ishida, Setsuo Takamuku
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2211-2220
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The selective excitation of contact charge-transfer (CCT) bands of 1,1-diarylethenes [Ar = 4-MeOC6H4 (1a); 4-MeC6H4 (1b); Ph (1c)] with molecular oxygen in CH2Cl2 and MeCN resulted in the formation of the corresponding 3,3,6,6-tetraaryl-1,2-dioxanes (2) as a primary product, together with diaryl ketones (3). The reaction mechanism and intermediates for the production of 2 and 3 were studied in terms of the effects of the solvent polarity, additives, substituents on the aromatic rings, and the excitation wavelength on the product distribution, as well as in terms of the result of the photolysis of 2. On the basis of these results, it was shown that 2 was produced through dimer cation radicals of 1, whereas 3 was formed through the photolysis of 2 and the autoxidation of 1 initiated by neutral radical species, which must have been generated by the reaction of monomer cation radicals of 1 (1•+) with a superoxide anion radical. In particular, the formation of 2 depended to a large degree on the solvent polarity; namely, 2 was produced more efficiently in CH2Cl2 with moderate polarity rather than in MeCN with high polarity. Moreover, the reactivities of monomer and dimer cation radicals of 1 were investigated by γ-radiolyis and pulse radiolysis. For 1a and 1b, the transient-absorption spectra of their dimer cation radicals trapped by oxygen molecules were directly observed at 365 ns after pulse irradiation. The reactivities of 1•+ are also discussed based on the optimum structure, charge density, and spin density, obtained by semi-empirical molecular orbital calculations (PM3 method).
  • Takeji Enya, Hitomi Suzuki, Yoshiharu Hisamatsu
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2221-2228
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The reaction of benzanthrone (7H-benz[d,e]anthracen-7-one, 1) with nitrogen dioxide alone or in admixture with ozonized oxygen has been investigated in polar and nonpolar organic solvents at different temperatures. A remarkable change of product distribution was observed depending on the solvent employed; 3-nitrobenzanthrone (4) was the main product from the reaction in dichloromethane, while 2-nitrobenzanthrone was obtained as the major product in tetrachloromethane. Addition of protonic acid or inorganic solid support was found to promote the reaction, favoring the formation of the former nitro compound at the expense of the latter. All major products were identified. The variation of isomer distribution depending on the conditions employed has been discussed in terms of the competition between the homolytic and heterolytic mechanisms involved in the nitration of ketone 1. On the basis of the results obtained, the atmospheric formation of the genotoxic nitro ketone 4 has been briefly discussed.
  • Hiroyuki Higuchi, Shima Yoshida, Yoshiyuki Uraki, Juro Ojima
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2229-2237
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    2,2′-(Dihexyl-2,2′-bithienylidene-5,5′-diylidene)bis(propanedinitrile)s (dihexylbithienoquinonoid derivatives), in which two 3-hexylthiophene moieties are connected with head-to-tail (HT) and tail-to-tail (TT) orientations, were synthesized. HT bithienoquinonoid was isolated in a single form together with a small amount of its bromo derivative, similarly to the case for the head-to-head (HH) orientational isomer. On the other hand, TT isomer exhibited a peculiar feature in solution, affording an equilibrium mixture of two geometrical isomers. Electronic and electrochemical properties of these bithienoquinonoids were studied and compared with those of HH isomer. The results proved that all these bithienoquinonoid compounds possess highly polarizable and electron-acceptable properties. HH bithienoquinonoid was reduced through one two-electron transfer process, while HT and TT isomers were reduced through two one-electron transfer processes via stable radical anions to the corresponding dianions.
  • Tetsuya Satoh, Jun-ichi Inoh, Yoshiki Kawamura, Yuichiro Kawamura, Mas ...
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2239-2246
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Biphenyl-2-ols undergo regioselective mono- and diarylation upon a treatment with aryl iodides in the presence of a palladium catalyst in DMF using Cs2CO3 as a base to produce 1,1′ : 2′,1″-terphenyl-2-ol and 2′,6′-diphenylbiphenyl-2-ol and their derivatives. The reaction of 1-naphthol selectively occurs at its 8-position to give 8-aryl-1-naphthols. In the reaction of 2-naphthol with aryl bromides, diarylated compounds, 1-(2-arylphenyl)-2-naphthols, are formed as the single major products. Under similar conditions, benzyl ketones, phenylacetonitrile, and methyl phenylacetate are arylated at their benzylic position.
  • In-Seon Kim, Tetsuro Nakamura, Mitsuru Itoh
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2247-2251
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The magnetic properties of 8H-type hexagonal-type Ba(Na1/4Ru3/4)O3 having a 2D geometry of Ru5+(t2g3) ions were studied by magnetic-susceptibility measurements in the temperature range 5 K < T < 700 K. In this structure, the face-shared RuO6 octahedra form (Ru2O9)8− clusters with a 2D array, which are sandwiched by 2D layers of the NaO6 and the RuO6 corner-shared octahedra. The magnetic data show an antiferromagnetism-like behavior, and could be well fitted to a Curie-Weiss law above 520 K with μeff = 3.74 μB and θ = −1330 K. At a lower temperature range of 262 K < T < 520 K, it showed a reduced magnetic moment of μeff = 2.32 μB and θ = −221 K by a new Curie–Weiss law fit. The χ(T) behavior showed a strong external field dependence below 262 K, and magnetic anomaly peaks could be observed in low-field FC data at 30, 110, and 180 K, respectively. The magnetic properties of Ba(Na1/4Ru3/4)O3 are discussed concerning both a long-range 3D antiferromagnetic order and a spin-glass-like behavior.
  • Masahiro Uekawa, Yasuo Miyamoto, Hitoshi Ikeda, Katsuaki Kaifu, Tadao ...
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2253-2258
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    Europium complexes with new β-diketone ligands with fluorene for organic electroluminescent (EL) devices have been synthesized and their properties examined. The absorption spectra of the complexes were varied by changing the conjugated system of the β-diketone; also, the energy transfer from the host material to the europium complexes and the intramolecular energy transfer have been improved. Concerning the volatility, the thermal properties of the europium complexes were improved by using phenanthroline derivatives. We fabricated organic EL devices using the synthesized complexes, and investigated the luminance of the devices.
  • Gerhard Nuspl, Masataka Nagaoka, Kazunari Yoshizawa, Fumihito Mohri, T ...
    原稿種別: Accounts
    専門分野: AI
    1998 年 71 巻 9 号 p. 2259-2265
    発行日: 1998年
    公開日: 2006/06/05
    ジャーナル 認証あり
    The minimum energy migration path and the minimum barrier height of lithium diffusion are discussed for the layer compound LixCoO2. The Universal Force Field (UFF) is adapted for use in solid state compounds. Molecular dynamics simulations with additional impulse dynamics method, performed at a microcanonical ensemble, point out that the lithium migration between the Co–O octahedron layers takes place by ion hopping from one octahedral to another octahedral site via an interstitial tetrahedral site. The barrier height of lithium migration is estimated to be 28.7 kJ mol−1 (0.30 eV) for an original layer distance of 2.54 Å; a potential energy profile is developed from molecular mechanics calculations. The observation that the repulsive van der Waals interaction between Li+ and neighboring O2− ions is the most important contribution to the barrier height is consistent with the fact that the activation energy of lithium diffusion is very sensitive to the layer distance, within the experimentally observed values.
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