Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 80 , Issue 7
Showing 1-26 articles out of 26 articles from the selected issue
Vol. 80 Commemorative Accounts
  • Arnout Ceulemans, Erwin Lijnen
    2007 Volume 80 Issue 7 Pages 1229-1240
    Published: July 15, 2007
    Released: July 11, 2007
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    A uniform view of electronic degeneracies, resulting from finite point group symmetries, is developed. It relates any n-fold degeneracy to the geometrical structure formed by the set of equidistant points in a space with exactly n dimensions. Jahn–Teller interactions within the degenerate manifold can simply be represented as bond stretchings of this structure. This approach thus can be qualified as the “chemical perspective” to the study of vibronic instabilities. The procedure is described for two-fold, three-fold, four-fold, and five-fold degeneracies. As a result a simple general proof of the Jahn–Teller theorem can be obtained. The electronic degeneracy is connected to the reaction graph of the stable minima on the surrounding Jahn–Teller surface. The findings are illustrated with some structural and dynamic molecular examples.
    A structural analysis of electronic degeneracies provides a simple and uniform picture of the molecular JT effect. Fullsize Image
  • Michele Soleilhavoup, Guy Bertrand
    2007 Volume 80 Issue 7 Pages 1241-1252
    Published: July 15, 2007
    Released: July 11, 2007
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    Valence isomers are compounds featuring the same fragments connected in different ways. In this personal account, we describe how we first met by serendipity this kind of isomerism, and how later on we used the specific properties of phosphorus and boron to prepare two types of valence isomers that are not accessible with elements exclusively from the first long row. In the carbon series, benzene is calculated to be 608 kJ mol−1 lower in energy than its singlet diradical valence isomer, the anti-tricyclohexylene, but a tetraphosphorus analogue of the latter has been isolated. According to calculations, the parent amidinium salt is 541 kJ mol−1 more stable than its three-membered heterocyclic valence isomer, but in the phosphorus series, the difference in energy between the open and closed forms is only a few kJ mol−1; provided the right substituents are used, the cyclic form can be isolated. Lastly, among butadiene valence isomers, singlet cyclobutane-1,3-diyls were predicted only as transition states for the inversion of bicyclo[1.1.0]butane. In marked contrast, 1,3-dibora-2,4-diphosphacyclobutane-1,3-diyls can be prepared by valence isomerization of the corresponding butadiene derivatives and isolated under conventional experimental conditions.
    Valence isomers of benzene, amidinium salt, and butadiene that are not accessible with carbon and/or nitrogen can be prepared using phosphorus and boron. Fullsize Image
Award Accounts
The Chemical Society of Japan Award for 2002
  • Kimitsuna Watanabe
    2007 Volume 80 Issue 7 Pages 1253-1267
    Published: July 15, 2007
    Released: July 11, 2007
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    This report characterizes the structure and function of four modified nucleosides first identified by myself or members of my research group in thermophilic bacteria and animal mitochondria over the past 30 years. I identified 2-thioribothymidine (s2T) (or 5-methyl-2-thiouridine (m5s2U)) in 1974 at position 54 in the T loop of tRNAs from an extreme thermophile, Thermus thermophilus, as well as related thermophiles, and a good deal of evidence has shown that it is required for thermostabilization of tRNAs, functioning at high temperatures. The functional roles and the biosynthetic pathway of s2T are outlined here. My research group has identified three novel modified nucleosides, 5-formylcytidine (f5C), N-(uridine-5-ylmethyl)taurine (τm5U), and N-(2-thiouridine-5-ylmethyl)taurine (τm5s2U), at the first anticodon position of mitochondrial (mt) tRNAs from higher animals (f5C is present in tRNAMet, τm5U in tRNALeu(UUR) and tRNATrp, and τm5s2U in tRNAGln, tRNALys, and tRNAGlu). Their chemical structures were determined and their functional roles in translation were examined. Additionally, f5C at the first anticodon position of mt tRNAMet plays a crucial role in decoding the AUA codon (decoded as isoleucine in the universal genetic code system) as methionine, which will form the second topic of this article. Defective modification of τm5U and τm5s2U at the first anticodon position in human mt tRNALeu(UUR) and tRNALys, respectively, is the result of point mutations in these tRNAs in mitochondria. It is strongly suggested that these defects are the direct cause of two mitochondrial diseases, MELAS (mitochondrial encephalomyopathies, encephalopathy, lactic acidosis, and stroke-like episodes) and MERRF (myoclonus epilepsy associated with ragged-red fibers). Their molecular mechanisms are also discussed here. These studies would serve to highlight again the importance of modified tRNA nucleosides in the structure and function of tRNAs.
    The structure and function of four tRNA modified nucleosides from thermophilic bacteria and animal mitochondria were characterized. They function in thermostabilization of tRNA or selective decoding of the proper codons, which serves to highlight the importance of modified nucleosides. Fullsize Image
The Chemical Society of Japan Award for Creative Work for 2005
  • Eiji Nakata, Shinya Tsukiji, Itaru Hamachi
    2007 Volume 80 Issue 7 Pages 1268-1279
    Published: July 15, 2007
    Released: July 11, 2007
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    Proteins are one of the most sophisticated biomolecules that play important roles in many biological processes and recently have attracted much attention as a key molecular player in new fields of nanobio-science and -technology. To use protein molecules, suitable molecular interfaces for maintaining, regulating, and/or expanding the structure and activity of natural proteins are highly desirable. In addition, development of flexible strategies and new concepts to manipulate protein structures at precise atomic levels is an important challenge from the viewpoint of organic chemistry. In this account, we highlight two unique chemistry-based strategies, developed by our group, for incorporating unnatural molecules into natural proteins, which include (i) reconstitution of chemically modified cofactors with apo-proteins or -enzymes, and (ii) post-(photo)affinity labeling modification of natural proteins. Using these methods, various unnatural molecules were incorporated into natural proteins without any genetic manipulation to produce semi-artificial proteins, of which the function can be regulated, modulated, and/or read-out with help of the incorporated unnatural functionalities.
    Two unique chemistry-based strategies for incorporating unnatural molecules into natural proteins, which include (i) reconstitution of chemically modified cofactors with apo-proteins or -enzymes, and (ii) post-(photo)affinity labeling modification of natural proteins, are highlighted. Fullsize Image
The Chemical Society of Japan Award for Technical Development for 2004
  • Yoshitaka Izumi, Hiroshi Ichihashi, Yasumoto Shimazu, Masaru Kitamura, ...
    2007 Volume 80 Issue 7 Pages 1280-1287
    Published: July 15, 2007
    Released: July 11, 2007
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    The development of a new catalyst effective for the vapor-phase Beckmann rearrangement of cyclohexanone oxime has made it possible to establish a commercial process for the production of ε-caprolactam without producing any ammonium sulfate. Through fundamental studies of the catalyst, it was discovered that an MFI-type zeolite composed exclusively of silica had a high selectivity and activity for the vapor-phase Beckmann rearrangement. Based on acidity measurements and on the reactivity of oximes with different sizes as well as the calculation results of the deprotonation energies of some silanols, we have suggested that the active sites are nest silanols located close to their mouth of the micro pores. By addition of methanol into the reaction system, the selectivity for ε-caprolactam was markedly improved to the levels required for industrialization. A fluidized bed reactor was used for the reaction system in order to maintain a continuous production. By combining the ammoximation process for production of cyclohexanone oxime using the TS-1 catalyst and the vapor-phase Beckmann rearrangement, a commercial plant has been operating on a 60000 tons per year scale since April 2003, without any troubles.
    The development of a high silica MFI zeolite effective for the vapor-phase Beckmann rearrangement of cyclohexanone oxime made it possible to establish a commercial process for the production of ε-caprolactam without producing any ammonium sulfate, by Sumitomo Chemical Co., Ltd. Fullsize Image
Accounts
  • Yasutaka Honda, Hidekazu Arii, Takeshi Okumura, Akira Wada, Yasuhiro F ...
    2007 Volume 80 Issue 7 Pages 1288-1295
    Published: July 15, 2007
    Released: July 11, 2007
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    Three new complexes with FeIII2(μ-O)(μ-OH) core surrounded with one, two, and three amino groups, that is, (6-amino-2-pyridylmethyl)bis(pyridylmethyl)amine (MAPA), bis(6-amino-2-pyridylmethyl)(pyridylmethyl)amine (BAPA), and tris(6-amino-2-pyridylmethyl)amine (TAPA), which act as hydrogen-bonding sites, were synthesized and characterized by electronic absorption spectroscopy and X-ray diffraction analysis. Their structural bond parameters, Fe–N(pyridine), Fe–N(amine), and Fe–μ-O(H) bonds, Fe···Fe distance, and Fe–O–Fe angle, could be explained in terms of a combination of two conflicting interactions between NH2 and μ-O(H) groups, that is, a steric repulsion and a hydrogen-bonding interactions. The LMCT bands of μ-O to iron(III) may be affected by hydrogen-bonding interactions between NH and μ-O(H) groups, which are discussed in connection with the formation processes of compound Q and compound X in sMMO and RNR-R2, respectively.
    μ-Oxo-μ-hydroxodiiron(III) complexes with amino groups as an intramolecular hydrogen-bonding site were synthesized as an active center model for sMMO and RNR-R2, compounds Q and X, respectively, which were characterized by electronic absorption spectroscopic and X-ray structure analytic methods. Fullsize Image
BCSJ Award Article
  • Ayumi Kashiwada, Atsuko Sakakibara, Yohei Nakamura, Kiyomi Matsuda
    2007 Volume 80 Issue 7 Pages 1296-1301
    Published: July 15, 2007
    Released: July 11, 2007
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    We describe the synthesis and characterization of novel isoleucine zipper polypeptide dimers, connected with a maleimide-containing linker molecule, that can assemble into structurally defined heterotrimeric α-helical coiled coil dimers on the basis of architectural features of the polypeptide sequences. Linear- and crosslinked-isoleucine zipper polypeptide dimers were designed in this study. Circular dichroism spectroscopy, gel filtration, and HPLC analyses indicate that each polypeptide dimer can noncovalently assemble with four isoleucine zipper polypeptides and lead to heterotrimeric α-helical coiled coil dimer formation. Thus, we concluded that monodispersed dimerization of triple-stranded coiled coil was achieved for the first time. Moreover, the noncovalently assembled supramolecule may be useful as a the building-block for constructing artificial polypeptide fibrillogenesis systems.
    In this work, we demonstrated the noncovalent dimeric assembly of heterotrimeric α-helical coiled coil. Fullsize Image
 
  • Noritoshi Nanbu, Masahiro Takehara, Susumu Watanabe, Makoto Ue, Yukio ...
    2007 Volume 80 Issue 7 Pages 1302-1306
    Published: July 15, 2007
    Released: July 11, 2007
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    Successive fluorination of dimethyl carbonate (DMC) exerts a polar effect on various fundamental properties. We describe the temperature dependence of the mass density (ρ), refractive index (nD), relative permittivity (εr), dynamic viscosity (η), and kinematic viscosity (ν) of trifluorinated, difluorinated, and monofluorinated DMCs (TFDMC, DFDMC, and MFDMC, respectively). η decreased in essentially the same order as εr: DFDMC > TFDMC > MFDMC > DMC. However, ν and the boiling point of the TFDMC were lower than those of the MFDMC.
  • Viruthachalam Thiagarajan, Perumal Ramamurthy
    2007 Volume 80 Issue 7 Pages 1307-1315
    Published: July 15, 2007
    Released: July 11, 2007
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    Newly synthesized nonconjugated, but covalently linked, bichromophoric systems (ADDSA) contain a salicylideneaniline (SA) moiety linked to an acridinedione (ADD) fluorophore via a covalent bond. The absorption and fluorescence characteristics of the ADDSA systems in various solvents reveal that the dual fluorescence originates from two different chromophores in the same molecule. The solvent polarity independent, long wavelength anomalous emission originates from the keto form of SA moiety via excited state intramolecular proton transfer (ESIPT). The ESIPT pathway was further confirmed by the benzylideneaniline (BA) and ADD moieties coupled non-proton transfer model system (ADDBA). Absence of the longer wavelength anomalous emission in the steady state as well as the shorter lifetime component in the time-resolved study for ADDBA system supports ESIPT mechanism for long wavelength anomalous emission in ADDSA system.
  • Keiko Nakasone, Norio Nemoto
    2007 Volume 80 Issue 7 Pages 1316-1322
    Published: July 15, 2007
    Released: July 11, 2007
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    An X-ray diffraction study on the crystal structures of binary mixtures of very pure long-chain symmetrical ketone (K39) and n-alkane (C39) with an odd carbon number of 39 is presented. When the samples were prepared with the solution-crystallization method, which form two different types of solid solutions for the molar fraction (fm) of K39 above and below fm,c=0.204. From composition and temperature dependencies of a long period (L) and two subcell lengths (as and bs) determined from (00l), (200), and (110) reflections, respectively, we show that nearly the same crystal structure as that of pure C39 is maintained for the solid solutions in regime S1 where fm<fm,c, while K39 dominantly affects the crystal structures at room temperature in regime S2 where fm>fm,c. When temperature was raised above the solidus line of the phase diagram in the S2 regime, recrystallization occurred to form a solid solution very rich in the K39 component in the liquid–solid solution coexisting phase before final melting of K39. The solid–solid phase transition behaviors and resulting chain packing in the S1 regime are discussed in relation to anomalous anisotropy of linear thermal expansion coefficients along two lattice directions.
  • Hossein Roohi, Sayed Mostefa Habibi
    2007 Volume 80 Issue 7 Pages 1323-1330
    Published: July 15, 2007
    Released: July 11, 2007
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    The conformational preference for gauche structures over anti ones in the simple model molecules CH4−nClnS (where n=1 and 2) was examined in detail by means of Natural Bond Orbital (NBO) analysis. We also compared the origin of the anomeric effect in CH2ClSH and CH2FSH. The energetic preference at MP2/6-311+G(d,p) level was slightly greater in CH2ClSH than in CHCl2SH. NBO analysis at the HF/6-311+G(d,p)//MP2/6-311+G(d,p) level indicates that the conformational preference for gauche conformers over anti ones is the result of a wide variety of orbital interactions. However, the interaction between the lp(S) and σ(C–Cl) is the most important factor for stabilizing the gauche conformers. In all compounds studied here, the effect of electrostatic and steric contributions involved in the Lewis term on stability of gauche conformers was less important than the charge delocalization.
  • Kazuo Mukai, Tomoe Isozaki, Shin-ichi Nagaoka
    2007 Volume 80 Issue 7 Pages 1331-1334
    Published: July 15, 2007
    Released: July 11, 2007
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    The kinetics of reactions between water-soluble antioxidants (glutathione, uric acid, and cysteine) and vitamin E radicals in aqueous Triton X-100 micellar dispersions were studied by using a spectrophotometer, and the second-order rate constants for these reactions were compared to those for the corresponding reactions between vitamin C (ascorbic acid) and vitamin E radicals. These reactions are regarded as a model for regeneration of vitamin E by the water-soluble antioxidants in human blood, and the relative contributions of each antioxidant to the total regeneration in blood are discussed.
  • Hirotoshi Mori, Eisaku Miyoshi
    2007 Volume 80 Issue 7 Pages 1335-1340
    Published: July 15, 2007
    Released: July 11, 2007
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    The electronic and vibrational spectra of a proton–electron-coupled inorganic complex [Co(Hbim)(C6H4O2)(NH3)2]2 having multistable states, were theoretically investigated using density functional theory calculations using B3LYP parameters. The electronic excitation spectrum in the low-spin ground 1Ag state of the complex has no strong absorption in the visible region (600–700 nm), while in the high-spin 5A1 and 9Ag complexes, some prominent peaks were predicted in the visible region. Frequency analyses of the 1Ag, 5A1, and 9Ag states showed the strong band of the NH stretching vibration at 2690, 2120, and 2770 cm−1, respectively. Based on this, it is possible to distinguish 5A1 from 1Ag and 9Ag by measuring IR light absorption at 2120 cm−1, showing that [Co(Hbim)(C6H4O2)(NH3)2]2 would be a good candidate for use as optically durable molecular level memory.
  • Ayako Nakata, Takeshi Baba, Hiromi Nakai
    2007 Volume 80 Issue 7 Pages 1341-1349
    Published: July 15, 2007
    Released: July 11, 2007
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    The geometries and electronic structures in the lowest triplet (T1) states of psoralen, 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP), and their monoadducts were studied by performing density functional theory (DFT) calculations. It was shown that the pyrone ring of 8-MOP is cleaved in the T1 state and the cleaved pyrone ring loses the ability to bond to the thymine residue. Therefore, 8-MOP in the open-ring structure does not form a diadduct, which is thought to cause side effects. DFT calculations on 20 kinds of substituted psoralens showed that the cleavage of the pyrone ring in the T1 state can be controlled by substituting an electron-donating group, especially one having a strong electron-donating resonance effect, at the 8-position of psoralen.
  • Miharu Eguchi, Hiroshi Tachibana, Shinsuke Takagi, Donald A. Tryk, Har ...
    2007 Volume 80 Issue 7 Pages 1350-1356
    Published: July 15, 2007
    Released: July 11, 2007
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    Complexes formed with synthetic clay minerals and dicationic and tetracationic porphyrins were prepared. The Soret bands of the multicationic porphyrins shifted to longer wavelength upon the formation of a complex with clay. The clay sheets themselves and the porphyrin molecules on the clay surface were examined by use of atomic force microscopy (AFM) and polarized visible-light-attenuated total reflectance (ATR) spectroscopy (PV-ATR) with a waveguide system. The flat adsorption of the clay sheets on the glass substrates was confirmed by AFM. A theoretical treatment of the analysis by ATR spectroscopy was derived. The orientations of the multicationic porphyrin molecules on the clay sheets in water turned out to be nearly parallel (<5°) to the clay surface, based on the PV-ATR analysis.
  • Takanori Nishioka, Shigeru Mitsui, Isamu Kinoshita, Tamami Koshiyama, ...
    2007 Volume 80 Issue 7 Pages 1357-1367
    Published: July 15, 2007
    Released: July 11, 2007
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    A dinucleating ligand consisting of thiopyridyl groups appended to a p-xylene backbone reacts with copper(I) halides to afford dinuclear copper complexes with terminal halogeno ligands, which are in equilibrium with bridging halogeno dicopper complexes formed by rearrangement and loss one of the terminal halogeno ligands. The identity of the products was confirmed by using 1H NMR spectroscopy, electrospray ionization mass spectrometry, and X-ray structure analyses.
  • Takayuki Michi, Masaaki Abe, Junzo Matsuno, Kohei Uosaki, Yoichi Sasak ...
    2007 Volume 80 Issue 7 Pages 1368-1376
    Published: July 15, 2007
    Released: July 11, 2007
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    Densely packed redox-active self-assembled monolayers (SAMs) of monocarbonyl triruthenium complexes [Ru33-O)(μ-CH3COO)6(CO)(mpy)(C10PY)] (1) (mpy, 4-methylpyridine; C10PY, {(NC5H4)CH2NHC(O)(CH2)10S–}2), [Ru33-O)(μ-CH3COO)6(CO)(μ-C10PY)] (2), and [{Ru33-O)(μ-CH3COO)6(CO)(mpy)}2(μ-C10PY)] (3) have been constructed on an Au(111) electrode surface. They were characterized by infrared reflection absorption spectroscopy (IRRAS), spectroscopic ellipsometry, and contact angle measurement as well as cyclic voltammetry. Redox potential of the SAMs of 1 at the interface of aqueous electrolyte solutions shifted negatively as the concentration of HClO4 increased from 0.01 to 1.0 mol dm−3 with the slope of 0.059 V/decade and as the electrolyte was changed from H2SO4 (0.79 V vs. Ag|AgCl) to HNO3 (0.69 V) and HClO4 (0.59 V) at a fixed concentration of 0.1 mol dm−3. No significant difference in the redox potential was observed between the acid and its sodium salt. The effect is explained, as previously reported for the ferrocenylalkanethiol and non-carbonyl triruthenium SAMs, in terms of the effective ion pair formation in the order ClO4 > NO3 > SO42−. The rate of the CO dissociation reaction of the complex in the SAMs (complete within a few minutes at room temperature) that occurs in the oxidation state of Ru3III,III,III was not very sensitive to the applied electrode potential (0.6–0.8 V), but increased by ca. 2.5 times as the concentration of HClO4 (0.01–1.0 mol dm−3) was lowered, and by ca. one-order of magnitude as the electrolyte anions was changed from ClO4 to SO42− and NO3.
  • Yuji Tokunaga, Megumi Yoshioka, Tatsuya Nakamura, Tatsuhiro Goda, Ryuj ...
    2007 Volume 80 Issue 7 Pages 1377-1382
    Published: July 15, 2007
    Released: July 11, 2007
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    In this study, we synthesized dibenzo[22–30]crown ethers and dumbbell-like secondary ammonium salts having stoppers of varying bulk. These crown ethers formed pseudorotaxanes with the ammonium ions in solution and in the gas phase, as evidenced using NMR spectroscopy and MS/MS spectrometry, respectively. The association constants in solution were obtained through regulation of the association and dissociation rates by varying the nature of the stopper groups of the dumbbell-like ammonium ions. The [25]- and [26]crown ether/isopropylphenyl group, the [27]- and [30]crown ether/tert-butylphenyl group, and the [22]- and [23]crown ether/furyl group were matched pairs. 1H NMR spectra of mixtures (CDCl3/CD3CN) of the crown ethers and their matched ammonium salts indicated the presence of three sets of signals in solution: those of the crown ether, the ammonium salt, and their pseudorotaxane. Integration of pertinent signals allowed the association constants of pseudorotaxanes to be determined readily. Among the [22–30]crown ethers, the highest value of the association constant was that for the [24]crown ether/dibenzylammonium ion system; the [25–30]crown ether/ammonium ion systems exhibited moderate values of their association constants [Kexp=35–114 M−1 when using (ArCH2)2NH2+PF6 as the ammonium salt at 27 °C; Kexp=21 M−1 when using (ArCH2)2NH2+TsO at 27 °C]. The [22]- and [23]crown ethers interacted weakly [Kexp=6–14 M−1 when using (ArCH2)2NH2+TsO at 27 °C].
  • Takeshi Matsumoto, Yingjin Liu, Yoshimi Sueishi, Shunzo Yamamoto
    2007 Volume 80 Issue 7 Pages 1383-1390
    Published: July 15, 2007
    Released: July 11, 2007
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    The kinetics of the hydride-transfer reaction between methylene blue (MB+) and 1-benzyl-1,4-dihydronictinamide (BNAH) were studied in media containing cyclodextrins (β- and γ-CD) and surfactants (sodium dodecyl sulfate (SDS), dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and hexadecyltrimethylammonium bromide). Cationic surfactants decreased the apparent first-order rate constant (kobsd) above the cmc, while SDS increased kobsd just above the cmc and then decreased kobsd with increasing surfactant concentration. This behavior for cationic surfactants was typical of micellar effects due to a separation of the reactants by the micelles. BNAH associated with micelles, whereas MB+ ions were repelled from the cationic interface of the micelles. Binding of BNAH and MB+ to the same SDS micelle enhanced the reaction, but dilution of reagents within the micellar interface with the increase in [SDS] caused a decrease in kobsd. In β-CD–cationic surfactant mixtures, the results were interpreted in terms of the model which takes into account the formation of CD–BNAH, CD–MB+, and CD–surfactant complexes and the association of BNAH with micelles. The decrease in kobsd with increasing surfactant concentration observed in γ-CD–cationic surfactant mixtures can be explained by the decrease in the concentration of free γ-CD by the formation of 1:1 and 2:1 complexes of surfactant monomer with γ-CD.
  • Wataru Yamada, Yasunori Kitaichi, Hirotaka Tanaka, Tomohide Kojima, Mi ...
    2007 Volume 80 Issue 7 Pages 1391-1401
    Published: July 15, 2007
    Released: July 11, 2007
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    The enantioselective chemical fixation of CO2 into an epoxide was developed using an optically active ketoiminatocobalt(II) complex as a chiral Lewis acid. In the presence of a catalytic amount of the cobalt complex and amine base, enantioselective CO2 fixation with an epoxide proceeded with kinetic resolution to afford the corresponding carbonate along with unreacted epoxide, both of which were optically active. To improve their enantioselectivities, the ligand structures of the cobalt complexes and amine bases were examined. Thus, the optimized catalytic system was successfully applied to various epoxides to obtain the corresponding optically active cyclic carbonates and to recover epoxides with good-to-high enantioselectivities.
  • Hiroyuki Kurata, Hideki Takakuwa, Naoaki Imai, Kouzou Matsumoto, Takes ...
    2007 Volume 80 Issue 7 Pages 1402-1404
    Published: July 15, 2007
    Released: July 11, 2007
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    2,5-Bis(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-2,5-dihydrothiazole, which is to our knowledge, the first p-terphenoquinone incorporating a 1,3-thiazole ring, had a sharp and strong absorption in the visible region and good electron affinity enhanced by sp2 nitrogen atom. Alkali-metal reduction afforded the corresponding dianion, which showed strong fluorescence.
  • Hirofumi Kondo, Yasuyo Nishida
    2007 Volume 80 Issue 7 Pages 1405-1412
    Published: July 15, 2007
    Released: July 11, 2007
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    In thin film magnetic recording media, the carbon protective layer and the outermost lubricant layer have a significant influence on the tribological properties. It is thought that the functional groups on the surface of the carbon influence the adsorption of the lubricant. The present study describes the identification and quantification of the functional groups on the surface of magnetic thin film media based on an X-ray photoelectron spectroscopy (XPS) preceded by chemical derivatization. The number of functional groups on the surface of the carbon protective layer was obtained from the ratio of the fluorine and carbon in the XPS spectrum. Gas-phase chemical modification was found to be preferable as a pretreatment for surface analysis, and the number of carbonyl, hydroxy, and carboxylic acid groups were directly determined. The number of hydroxy group was higher immediately after deposition, and the carbonyl group, of which the concentration rapidly increased with exposure time to air, became the most abundant. Both groups improved the affinity of the lubricant and will probably lead to a better lubricity.
  • Hirohito Umezawa, Shuji Okada, Hidetoshi Oikawa, Hiro Matsuda, Hachiro ...
    2007 Volume 80 Issue 7 Pages 1413-1417
    Published: July 15, 2007
    Released: July 11, 2007
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    Partially fluorinated skeleton of 4-[2-(4-dimethylamino-2,3,5,6-tetrafluorophenyl)ethynyl]-2,3,5,6-tetrafluoro-N,N,N-trimethylanilinium (2) was synthesized as a second-order nonlinear optical (NLO) material to decrease the absorption around 1.3 and 1.5 μm, which deteriorates the device efficiency. Several salts of 2 were prepared, and we found that the trifluoromethanesulfonate salt of 2 (2b) had a shorter absorption-maximum wavelength compared to that of 4-nitroaniline (pNA). From hyper-Rayleigh scattering (HRS) measurement, the β value of 2b was found to be about 8 times greater than that of pNA. We also performed X-ray crystallographic analysis of 2b and estimated NLO coefficient (d) by the oriented gas model. We found that diagonal component of 2b (d11=610 pm V−1) was about 14 times greater than that of 2-methyl-4-nitroaniline and off-diagonal component of 2b (d12=155 pm V−1) was about 6.5 times greater than that of N-(4-nitrophenyl)-L-prolinol. Compound 2b should be an excellent candidate for NLO applications.
  • Yoshihiro Sugi, Hiroyoshi Maekawa, Shafeek Abdul Rashid Mulla, Akira I ...
    2007 Volume 80 Issue 7 Pages 1418-1428
    Published: July 15, 2007
    Released: July 11, 2007
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    Alkylation, i.e. isopropylation, s-butylation, and t-butylation, of biphenyl (BP) was examined over fourteen-membered ring (14-MR) zeolites, CIT-5, UTD-1, and SSZ-53, in order to elucidate the relationships between structure of zeolites and bulkiness of alkylating agents on the shape-selective catalysis. CIT-5 zeolite (CFI) yielded 4,4′-diisopropylbiphenyl (4,4′-DIPB) in the level of 50–60% in the isopropylation in the range of 150–300 °C. 2,2′-, 2,3′-, and 2,4′-DIPB (2,x′-DIPB) isomers were obtained as the predominant DIPB isomers at lower temperatures, and the formation of 3,4′- and 3,3′-DIPB isomers increased with an increase in the temperature. However, the selectivities were in the level of 10–15% for UTD-1 (DON) and SSZ-53 (SFH) zeolites in the range of 150–350 °C. The s-butylation with 1-butene gave results similar to the isopropylation, although the selectivities for 4,4′-di-s-butylbiphenyl (4,4′-DSBB) were higher than those for 4,4′-DIPB at 250 °C: 80–85% for CFI, 40–50% for DON, and 30–40% for SFH. High selectivity for 4,4′-di-t-butylbiphenyl (4,4′-DTBB) was observed in the t-butylation at 250 °C: 95% for CFI, 90% for DON, and 80% for SFH. These differences are due to the spatial difference in their channels, and also due to bulkiness of alkylating agents, propene, 1-butene, and 2-methylpropene. The selectivity for 4,4′-dialkylbiphenyl (4,4′-DABP) was governed by the exclusion of the bulky DABP isomers at the transition state by steric restriction in the zeolite channels.
  • Takahiro Tago, Norikazu Kuwashiro, Hiroyuki Nishide
    2007 Volume 80 Issue 7 Pages 1429-1434
    Published: July 15, 2007
    Released: July 11, 2007
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    A series of highly acid-functionalized poly(phenylene oxide)s and poly(phenylene sulfone) were prepared and proton conductivity in their membranes is discussed. Phosphorylated poly(phenylene oxide)s were prepared via the oxidative polymerization of phosphonoxyphenols in alkaline water, along with a facile monomer preparation. A poly(phenylene oxide) bearing a sulfamide acid group was prepared by reacting amidosulfate with the corresponding carboxylated poly(phenylene oxide). A sulfonated poly(phenylene sulfone) was prepared by hydrogen peroxide oxidation of the sulfonated poly(phenylene sulfide). All these acid-functionalized polymers showed appropriate thermal stability based on the aromatic backbone. The polymers had a high ion-exchange capacity, were water-soluble, but gave transparent and flexible membranes after compositing with the poly(ethylene oxide). Some of the membranes displayed a high proton conductivity of 10−4 S cm−1 at 120 °C under dry conditions.
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