Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 82 , Issue 10
Showing 1-16 articles out of 16 articles from the selected issue
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  • Tomoo Miyahara, Jun-ya Hasegawa, Hiroshi Nakatsuji
    2009 Volume 82 Issue 10 Pages 1215-1226
    Published: October 15, 2009
    Released: October 08, 2009
    JOURNALS OPEN ACCESS
    The singlet excited states of oxirane and thiirane derivatives, ethylene oxide, (R)-methyloxirane, (2S,3S)-dimethyloxirane, ethylene sulfide, (R)-methylthiirane, and (2S,3S)-dimethylthiirane, were calculated employing the symmetry-adapted cluster (SAC)/SAC-configuration interaction (CI) method. The rotatory strengths of the CD spectra were calculated in the velocity form, which is gauge-origin independent. Both the ultraviolet (UV) spectra and the circular dichroism (CD) spectra obtained with the SAC-CI method were in good agreement with the experimental spectra. In oxirane derivatives, the low-lying excited states were composed of excitations from n and σ orbitals to s, p, and d Rydberg orbitals. The excitation from the σ orbital was especially important in (2S,3S)-dimethyloxirane because of the steric effect of the methyl substitutions. However, in thiirane derivatives, the excitations to the low-lying excited states were only from the n orbital.
    Both the CD and UV spectra of oxirane and thiirane derivatives obtained with the SAC-CI method were in good agreement with the experimental spectra. The rotatory strengths of the CD spectra were calculated in the velocity form. Fullsize Image
BCSJ Award Article
  • Hiroyuki Noda, Hiromitsu Uehara, Masaaki Abe, Takayuki Michi, Masatosh ...
    2009 Volume 82 Issue 10 Pages 1227-1231
    Published: October 15, 2009
    Released: October 08, 2009
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    We present here an in situ scanning tunneling microscopy (STM) study of potential-induced reactions of oxo-centered acetato-bridged triruthenium clusters on Au(111) under electrochemical conditions, in which (i) reversible interconversion between two different redox states of the cluster and (ii) spontaneous dissociation of CO from the cluster were probed and visualized. It is known that the triruthenium complex [Ru33-O)(μ-CH3COO)6(CO)(4-methylpyridine){(NC5H4)CH2NHC(O)(CH2)10S}] (1), which is in the mixed-valent {(RuII–CO)RuIIIRuIII} state, on Au(111) is one-electron oxidized to cationic complex 1+ which corresponds to a {(RuIII–CO)RuIIIRuIII} oxidation state. The redox reaction is reversible on a cyclic voltammetry timescale. Complex 1+ undergoes irreversible dissociation of CO in an aqueous phase on a longer timescale (ca. minutes) to form an aqua ligand-coordinated complex, 2+, which is expressed as {(RuIII–OH2)RuIIIRuIII}. The reversible redox reaction (1 1+) and the irreversible ligand substitution reaction (1+2+) were independently examined with in situ STM in a monolayer level by visualizing molecular-sized spots showing a different extent of brightness in STM images. We show here that the molecular-sized spots corresponding to 1, 1+, and 2+ are resolved by their brightness, which strongly depends on both the oxidation states and the ligand nature of the clusters. By employing multiple fast scans at an applied potential of +0.80 V vs. Ag/AgCl, we obtained STM images that follow the irreversible 1+2+ reaction on the surface, from which a rate constant of the CO release was calculated to be 1.9 (±0.2) × 10−2 s−1 (25 °C; in contact with 0.1 mol dm−3 aqueous HClO4 solution). The difference in brightness of the molecular spots is rationalized in terms of orbital-mediated tunneling by considering the difference in electronic states of the dπ–pπ system in the μ3-O triruthenium cluster.
    Potential-induced reversible redox interconversion and irreversible ligand-substitution reaction of triruthenium clusters on an Au(111) electrode surface have been successfully visualized at a monolayer level with use of in situ STM under electrochemical conditions. Fullsize Image
 
  • Kazuma Gotoh, Takahiro Ueda, Taro Eguchi, Koji Kawabata, Kenji Yamamot ...
    2009 Volume 82 Issue 10 Pages 1232-1239
    Published: October 15, 2009
    Released: October 08, 2009
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    The pore structure of hard carbon samples made from two kinds of phenolic resins by heating between 1073 and 1473 K was investigated by 129Xe NMR. The difference of porous structure of hard carbon samples by heat treatment temperature, which was difficult to analyze precisely by general gas adsorption methods, could be evaluated by Xe NMR at an equilibrium state of xenon gas adsorption. Carbon samples produced by heating precursors under a 0.1 MPa xenon atmosphere showed stronger NMR signals than carbon heated at reduced pressure, despite their almost identical powder X-ray diffraction (XRD) patterns. Applying this method, the dependence of NMR spectra on heating temperature between 1073 and 1473 K was examined. A carbon sample consisting of smaller particles showed almost constant shift values at about 102 ppm, while the peak of another sample with larger particles shifted between 118 and 82 ppm depending on the heating temperature. Then, almost all entrances of each sample closed above 1273 K. Using NMR with the improved heat-treatment by xenon gas, we evaluated pores in hard carbon that were hard to access from the outer surface of the hard carbon.
  • Kikujiro Ishii, Hideyuki Nakayama, Ryo Moriyama, Yuki Yokoyama
    2009 Volume 82 Issue 10 Pages 1240-1247
    Published: October 15, 2009
    Released: October 08, 2009
    JOURNALS OPEN ACCESS
    Ethylbenzene (EB) films prepared on cold metal substrates by vapor deposition in vacuum show a curious light scattering in the supercooled liquid (SCL) state when the temperature is raised at a constant rate. To investigate the cause of this phenomenon, we examined the behavior of similarly prepared samples of a series of alkylbenzenes. We found that the vapor-deposited glass of propylbenzene (PB) and isopropylbenzene (IPB) showed a deposition-temperature (Td) dependence of the initial molar volume (Vm) on deposition similar to EB glass. Interestingly, the samples of the three compounds, which were formed initially as glasses with Vm much larger than that of SCL at the same temperature, exhibited the curious light scattering when they transformed to SCL states after the temperature elevation to above their glass-transition temperature, while the corresponding samples with initial Vm smaller than that of SCL did not exhibit this light scattering. On the basis of these observations, a hypothesis on the cause of the light scattering in the SCL state is proposed in relation to structural transformation between different SCL states. A microscopic mechanism of the formation of a high-density glass with Vm smaller than that of SCL is briefly discussed by referring to the observations of toluene samples which showed a slightly different Td dependence of Vm and did not show the curious light scattering in the SCL state.
  • Umpei Nagashima, Shin-ichi Nagaoka
    2009 Volume 82 Issue 10 Pages 1248-1249
    Published: October 15, 2009
    Released: October 08, 2009
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    A reason for the greater chemical shift difference observed in a deep core level than a shallow level is presented.
  • Hiroshi Takashima, Satomi Shibata, Yuka Sekiguchi, Yoshitane Imai, Kei ...
    2009 Volume 82 Issue 10 Pages 1250-1257
    Published: October 15, 2009
    Released: October 08, 2009
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    In order to understand the detailed mechanisms of stereoselective photoinduced electron-transfer (ET) reactions of zinc-substituted myoglobin (ZnMb) with optically active viologens by flash photolysis, we prepared new optically active agents, such as (R,R)- and (S,S)-1,1′-bis(3-hydroxy-2-methylpropyl)-4,4′-bipyridinediylium dichloride ([BMV]Cl2). The photo-excited triplet state of ZnMb, 3(ZnMb)*, was successfully quenched by (R,R)- and (S,S)-[BMV]2+ ions to form the radical pair of ZnMb cation (ZnMb•+) and (R,R)- and (S,S)-[BMV]•+, followed by a thermal back ET reaction to the ground state. The ratio of the rate constants (kq) for ET quenching at 25 °C, kq(R,R)/kq(S,S) = 1.1, indicates that the (R,R)-[BMV]2+ preferentially quenches 3(ZnMb)*. The selectivity of the rate constants (kb) for the back ET from (R,R)- and (S,S)-[BMV]•+ to ZnMb•+ at 25 °C was kb(R,R)/kb(S,S) = 0.83. The highest stereoselectivity of 1.3 for [BMV]•+ was found at low temperature (10 °C) in the thermal back ET reaction, where ΔΔH (R–S) = 6.2 ± 1.9 kJ mol−1 and ΔΔS (R–S) = 19 ± 2 J mol−1 K−1 were obtained. The structural differences between [BMV]2+ and the other viologens imply that the bulky aromatic substituent seems to be more important than the distance from the chiral center to the viologen moiety in order to enhance the ET stereoselectivity.
  • Motoharu Tanaka, Masaaki Tabata
    2009 Volume 82 Issue 10 Pages 1258-1265
    Published: October 15, 2009
    Released: October 08, 2009
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    Equations derived on the basis of mechanistic considerations have been utilized to calculate the stability constants of binary and ternary copper(II) complexes of amine(s) or aminocarboxylates. Calculated values of 185 copper(II) amine complexes have been compared with the observed. For 89 complexes including ammonia, ethylenediamine, cyclohexane-1,2-diamine, imidazole, pyridine, and some substituted analogs, the calculated values agree with the observed within 0.3 log unit. These complexes may be regarded as regular. Among the remaining non-regular complexes we find some complexes with lower stability constants due to steric hindrance, and some others with higher constants resulting from aromatic π–π interactions and/or hydrophobic interactions between coordinated ligands. Mechanistic considerations have also been successfully utilized to predict stability constants of polyamine and aminocarboxylate chelates of nickel(II), cobalt(II), and copper(II) according to Adamson’s approach.
  • Mariko Saito, Hisako Sato, Yukie Mori, Yutaka Fukuda
    2009 Volume 82 Issue 10 Pages 1266-1273
    Published: October 15, 2009
    Released: October 08, 2009
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    Crystal structures of nickel(II), copper(II), and palladium(II) complexes with (R)-/(S)-2,2′-bis(salicylideneamino)-1,1′-binaphthyl were determined. The nickel complex 1 is binuclear consisting of two Ni2+ ions and homochiral two ligand dianions in the crystal. Each Ni2+ ion has a trans-N2O2 square-planar coordination sphere. Either the metal ion or the ligand is less distorted in binuclear complex 1 as compared with the mononuclear copper(II) complex, which has an intermediate structure between square-planar and tetrahedral forms. When dissolved in solvent, complex 1 dissociates into mononuclear species. It is likely that crystallization involves partial ligand-exchange of a mononuclear complex with another molecule of the same chirality to form a homochiral dimer in a self-sorting fashion. Nickel complex with 2,2′-bis(4-methoxysalicylideneamino)-1,1′-binaphthyl (2) forms a 1:1 adduct with (R)-2-(1-hydroxyethyl)pyridine in chloroform solution. The binding constant of (R)-2 is twofold higher than that of (S)-2, which means that the adduct formation proceeds with enantio-differentiation.
  • Zhong Yu, Toshiyuki Shimizu, Toshi Tominaga, Takashi Okubo, Masahiko M ...
    2009 Volume 82 Issue 10 Pages 1274-1276
    Published: October 15, 2009
    Released: October 08, 2009
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    Columnar assembly of dimeric FeII Schiff base complex based on twisted-overlap orientation of salophen platforms exhibits ferromagnetic interactions at low temperature, which is ascribable to μ-phenoxy-bridged Fe…Fe interactions and π–π interactions.
  • Makoto Handa, Yoshiyuki Ishitobi, Taku Yakuwa, Daisuke Yoshioka, Hidea ...
    2009 Volume 82 Issue 10 Pages 1277-1279
    Published: October 15, 2009
    Released: October 08, 2009
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    The reaction of copper(II) pentafluorobenzoate ([Cu2(O2CC6F5)4]) with pyrazine (pyz) in methanol gave a polymer complex [Cu(O2CC6F5)2(pyz)]n. The pyz-bridged structure of Cu(O2CC6F5)2 was characterized by X-ray crystal structure analysis. Temperature-dependent magnetic susceptibility showed the existence of an antiferromagnetic interaction (J = −3.0 cm−1) within the polymer.
  • Akira Onoda, Masahiro Igarashi, Satoshi Naganawa, Kiyomi Sasaki, Shiny ...
    2009 Volume 82 Issue 10 Pages 1280-1286
    Published: October 15, 2009
    Released: October 08, 2009
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    Neutral zinc porphyrin containing flexible alkyl linker, 5-[4-(5-hydroxypentyloxy)phenyl]-10,15,20-tri-p-tolylporphyrinatozinc, was attached to the 5′ ends of 20- and 30-bp oligodeoxynucleotides (ODN) by solid-phase synthesis. Zinc porphyrin-modified double-stranded DNA (dsDNAs), which included dsDNAs with porphyrin moieties on one end and on both ends (ZnPor–ds20, ds20–ZnPor, ZnPor–ds20–ZnPor, ZnPor–ds30, ds30–ZnPor, and ZnPor–ds30–ZnPor), were successfully prepared and were analyzed by variable-temperature UV–vis spectroscopy and CD measurements to elucidate the interaction behavior of the porphyrin ring. Detailed investigation revealed that the zinc porphyrin–DNA conjugates exhibited intra-duplex porphyrin–ODN interaction in a low-salt condition and inter-duplex porphyrin–porphyrin interaction in a high-salt condition.
  • Shinji Toyota, Rie Azami, Tetsuo Iwanaga, Daisuke Matsuo, Akihiro Orit ...
    2009 Volume 82 Issue 10 Pages 1287-1291
    Published: October 15, 2009
    Released: October 08, 2009
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    Three dianthrylethynes and an anthracene–acetylene trimer were conveniently synthesized by double elimination reactions starting from anthraldehydes and [(phenylsulfonyl)methyl]anthracenes. In the optimal one-shot process, a THF solution of these substrates and diethyl chlorophosphate was treated with LiHMDS at room temperature to give the desired alkynes in excellent yields without chromatographic purification. The structure of one of the intermediate vinyl sulfones was determined by X-ray crystallography.
  • Masayuki Wakioka, Yuichiro Mutoh, Ryo Takita, Fumiyuki Ozawa
    2009 Volume 82 Issue 10 Pages 1292-1298
    Published: October 15, 2009
    Released: October 08, 2009
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    A highly selective system for palladium-catalyzed polycondensation of (E,E)-1,4-bis(2-bromoethenyl)benzene ((E,E)-1) with 2,5-dioctyloxybenzene-1,4-diboronic acid (2a) to give all-trans poly[( p-phenylenevinylene)-alt-(2,5-dioctyloxy-1,4-phenylenevinylene)] (all-trans 3) has been investigated using (E)-styryl bromide ((E)-4) and 2,5-dioctyloxybenzeneboronic acid (5a) as model compounds of (E,E)-1 and 2a, respectively. The reaction of (E)-4 and 5a in toluene in the presence of Pd(PPh3)4 catalyst and aqueous K2CO3 base affords considerable amounts of homocoupling products (i.e., 1,4-diphenylbutadiene (13%) and 2,2′,5,5′-tetraoctyloxybiphenyl (22%)), together with (E)-2,5-dioctyloxystilbene ((E)-6a) as the cross-coupling product (30%). The use of aqueous NaOH as a strong base and Bu4NBr as a phase-transfer catalyst notably reduces the homocoupling products, and the use of Pd(PBut3)2 instead of Pd(PPh3)4 results in almost perfect selectivity of the cross-coupling product (E)-6a. Under optimized catalytic conditions, the desired all-trans 3 has been successfully prepared without notable defects in the polymer chain.
  • Kazutaka Hirakawa, Shoichiro Sano
    2009 Volume 82 Issue 10 Pages 1299-1303
    Published: October 15, 2009
    Released: October 08, 2009
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    Platinum, palladium, gold, rhodium, and silver monometallic nanoparticles protected by poly(N-vinyl-2-pyrrolidone), a water-soluble polymer, were prepared using an alcohol reduction method. Platinum/silver bimetallic nanoparticles were prepared by self-organization from the platinum and silver monometallic nanoparticles. Platinum nanoparticles showed the highest catalytic activity for the decomposition of hydrogen peroxide in the monometallic nanoparticles used in this study. Platinum, silver, and platinum/silver nanoparticles effectively catalyzed the decomposition of hydrogen peroxide generated from the autooxidation of hydroquinone, a derivative of carcinogenic benzene. The autooxidation of hydroquinone itself was hardly inhibited by platinum nanoparticles. The platinum nanoparticles in particular showed the highest catalytic activity per unit atom. The activity of a 2 µg platinum nanoparticle was comparable to that of 20 units of catalase. The modification of platinum nanoparticles with silver rather suppressed the activity of hydrogen peroxide decomposition. These results suggest that Pt nanoparticles can be used as antioxidants against oxidative chemical compounds.
  • Xinling Tang, Masaharu Tsuji, Michiko Nishio, Peng Jiang
    2009 Volume 82 Issue 10 Pages 1304-1312
    Published: October 15, 2009
    Released: October 08, 2009
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    The roles of Cl ions on the shape evolution of various silver (Ag) nanostructures including cubes, triangular bipyramids, and rods/wires in AgNO3/poly(vinylpyrrolidone) (PVP)/ethylene glycol (EG) solution have been investigated by changing the concentration of added NaCl, the reaction solution temperature, and the temperature of injection of NaCl to the original AgNO3/PVP/EG solution under oil-bath heating. The addition of different amounts of NaCl could tune morphologies and sizes of the final products from spheres via cubes to rods/wires. Reaction temperature decided the reduction power and the yield of bipyramids increased with decreasing the reaction temperature from 198 to 120 °C. Changing the solution temperature at which NaCl was introduced into the solution could effectively influence the yields of different Ag structures by adjusting the ratios of Ag and AgCl seeds formed in the solution. We found that AgCl could be an important precursor for the formation of the Ag cubes and bipyramids. The roles of Cl anions for the evolution of various Ag nanostructures have been discussed by taking account of the formation of AgCl as seeds, selective adsorption of Cl on {100} facets of Ag nanoparticles, and oxidative etching of the Ag particles by Cl/O2.
  • Hitomi Nakajima, Yasunori Oumi, Tsuneji Sano, Hideaki Yoshitake
    2009 Volume 82 Issue 10 Pages 1313-1321
    Published: October 15, 2009
    Released: October 08, 2009
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    We demonstrate that the dehydration condensation of 3-aminopropylsilane (APTES) and 3-(2-aminoethyl)aminopropylsilane (AeAPTES) in the presence of alkylsuccinate and alkanoic acid provide layered polysiloxanes where the interlayer is filled with self-assembled carboxylate. Their structure was investigated by XRD, IR, and 29Si NMR. Lamellar solids were successfully obtained by the combination of monocarboxylate–APTES and dicarboxylate–AeAPTES, while the addition of alkanol and TEOS was necessary for the synthesis by cross combinations, dicarboxylate–APTES and monocarboxylate–AeAPTES. The series of lamellar solids with different interlayer distance are formed with alkylsuccinate and AeAPTES. The d-spacing is increased linearly with the number of carbons in the alkyl chain of surfactant. Only T3 species is detected in the 29Si NMR spectrum of hexadecylsuccinic acid–AeAPTES, implying that the structure of polysiloxane is a thin layer with complete condensation of silane molecules. This structural uniqueness is also supported by the IR bands due to Si–O–Si asymmetric vibration at 1132–1140 cm−1, suggesting a large Si–O–Si angle. This is because an angle near 180° is necessary for the structure of a R–SiO1.5 layer solid that has organic groups equally populated on both sides. The amount of Fe3+ sorbed in diaminoalkylpolysiloxanes was smaller than in monoaminoalkylpolysiloxane.
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