Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 80 , Issue 5
Showing 1-27 articles out of 27 articles from the selected issue
Vol. 80 Commemorative Accounts
  • Markus Albrecht, Roland Fröhlich
    2007 Volume 80 Issue 5 Pages 797-808
    Published: May 15, 2007
    Released: May 14, 2007
    JOURNALS FREE ACCESS
    The self-assembly of well-defined metallosupramolecular aggregates highly depends on the symmetry of the ligands as well as of the metals. Approaches in which symmetry considerations allow the stepwise—“hierarchical”—assembly of helicate-type complexes from very simple catechol derivatives are described. In addition helicates and meso-helicates are stereoselectively obtained by the use of linear ligands possessing the relevant symmetry element for the formation of either diastereomer (even–odd principle). In case of helicates, this allows the preparation of enantiomerically pure complexes. Finally, the self-assembly of tetrahedral M4L4 complexes is described using either constrained flexible or highly predisposed rigid ligands.
    The self-assembly leading to metallosupramolecular aggregates like helicates, meso-helicates or M4L4 tetrahedra is controlled by the symmetry of the molecular building blocks: ligands as well as metal ions. Fullsize Image
  • Sunggak Kim, Sangmo Kim
    2007 Volume 80 Issue 5 Pages 809-822
    Published: May 15, 2007
    Released: May 14, 2007
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    Tin-free radical reactions based on α-scission of alkylsulfonyl radicals are very useful for the formation of carbon–carbon bonds and include allylation, acylation, cyanation, vinylation, and carbonylation. For secondary, tertiary, and benzylic radicals, it is possible to use the corresponding iodides as precursors but the primary radicals still require the use of phenyl tellurides or alkyl allyl sulfones. Especially, alkyl allyl sulfones are highly efficient and most reliable primary alkyl radical precursors for the further formation of carbon–carbon bonds. The present approach is very useful for introducing various functional groups such as carbonyl and alkenyl groups under tin-free conditions.
    Tin-free radical reactions based on α-scission of alkylsulfonyl radicals are very useful for various carbon–carbon bond formations. Especially, alkyl allyl sulfone precursors are highly efficient and most reliable to generate primary alkyl radicals under tin-free conditions for the further formation of carbon–carbon bonds. Fullsize Image
Award Accounts
The Chemical Society of Japan Award for Creative Work for 2004
  • Hiroshi Sugiyama
    2007 Volume 80 Issue 5 Pages 823-841
    Published: May 15, 2007
    Released: May 14, 2007
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    Fifty years after the discovery of the double-helical structure of DNA, the complete sequence of the human genome has been determined. All genetic information, which is necessary for life, is written in 30 billion base pairs of DNA. Many diseases, including cancer, and hereditary and viral diseases, can now be understood at the DNA sequence level. Local DNA conformations are also thought to play an important role in biological processes, such as gene expression. Therefore, DNA sequences and local DNA conformations are the targets of novel drugs that would precisely switch certain genes on or off. Modified bases that perform various functions can also be incorporated into defined DNA sequences. DNA can now be synthesized by the phosphoramidite method and amplified by PCR, and by using organisms such as Escherichia coli, DNA becomes a promising unit for nanotechnology applications. In this review, I focus on our efforts in understanding the DNA reactivity, structure, and function of DNA. The prospective uses of the chemical biology of DNA will also be discussed.
    Our long term efforts in understanding of DNA reactivity, structure, and function are reviewed. The prospective uses of the chemical biology of DNA are also discussed. Fullsize Image
The Chemical Society of Japan Award for Creative Work for 2005
  • Yoshiyasu Matsumoto
    2007 Volume 80 Issue 5 Pages 842-855
    Published: May 15, 2007
    Released: May 14, 2007
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    This account describes excitation mechanisms and ultrafast nuclear dynamics at metal surfaces induced upon photon irradiation. After reviewing possible excitation mechanisms for photochemistry of adsorbates on metal surfaces, we discuss the ultra-violet photochemistry of saturated hydrocarbons, i.e., methane and cyclohexane, on metal surfaces. Although these alkanes in the gas phase do not absorb photons at ≈6 eV, CH bond dissociation takes place upon 6.4-eV photon irradiation on metal surfaces. Hybridization between CH antibonding orbitals of the alkanes and metal bands, forming a new band across the Fermi level, is proposed to be responsible for both the photochemistry and CH vibrational mode softening. Since electronic relaxation at metal surfaces takes place very rapidly, most of excited adsorbates do not proceed to dissociation and/or desorption, but rather they are vibrationally excited. To probe photo-induced nuclear motions in real time, we developed femtosecond (fs) time-resolved second harmonic generation spectroscopy on metal surfaces. This method was used to explore the dynamics of photo-excited coherent vibration at Pt(111) surfaces covered with alkali-metal atoms. Irradiation of fs pump-laser pulses induced coherent vibrational motions of the stretching vibration of alkali atoms with respect to the metal surface and the Rayleigh modes of the Pt surface, which manifest themselves in modulations of second harmonic intensity of probe pulses. We also demonstrated that selective excitation of a phonon mode can be achieved by using tailored light pulse trains.
    The stretching mode of alkali-metal adsorbates at a metal surface is coherently excited with femtosecond pump pulses and its decaying process is probed by using second harmonic generation in real time. Fullsize Image
  • Makoto Sasaki
    2007 Volume 80 Issue 5 Pages 856-871
    Published: May 15, 2007
    Released: May 14, 2007
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    The polycyclic ether class of marine natural products presents formidable and challenging synthetic targets due to their structural complexity and exceptionally potent biological activities. Over the past decade, however, their extremely limited availability from natural sources has precluded detailed biological studies on polycyclic ethers. Therefore, the supply of useful quantities of these natural products by chemical total synthesis has been strongly demanded. We developed a highly convergent strategy for the rapid assembly of a huge polycyclic ether array, which features Suzuki–Miyaura cross-coupling reaction of alkylboranes, generated from exocyclic enol ethers, with cyclic ketene acetal triflates or phosphates combined with reductive ring-closure. The utility of this strategy was demonstrated by its application to the convergent total synthesis of the natural products gambierol and gymnocin-A. These practical synthetic routes allowed for the first time systematic studies of the structure–activity relationships of the polycyclic ether class of natural products.
    The polycyclic ether class of marine natural products presents formidable and challenging synthetic targets due to their structural complexity and exceptionally potent biological activities. In this account, the development and application of a convergent strategy for the synthesis of natural polycyclic ethers are described. Fullsize Image
The Chemical Society of Japan Award for Young Chemists for 2005
  • Katsuro Hayashi, Masahiro Hirano, Hideo Hosono
    2007 Volume 80 Issue 5 Pages 872-884
    Published: May 15, 2007
    Released: May 14, 2007
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    A cage structure formed in a positively charged lattice framework of 12CaO·7Al2O3 (C12A7) is utilized to incorporate and release chemically unstable anions, imparting chemical and electronic activities to this material. High concentrations of oxygen radical anions, i.e. O and O2, are formed efficiently in these cages under a high oxygen activity condition. The O ion, which is the strongest oxidant among all the reactive oxygen species, can be extracted from the cages into an external vacuum by applying an electric field with thermal assistance. In contrast, hydrogen-reduction processes allow the formation of hydride (H) ions in the cage. H ion-incorporated C12A7 exhibits a persistent insulator–conductor conversion upon irradiation with ultraviolet-light or electron-beam. The irradiation-induced conversion mechanism and electronic transport characteristics are discussed on the basis of experimental evidence and first-principle theoretical calculations. Electrons released from the H ions are trapped by the cages and subsequent inter-cage hopping of the electrons is responsible for the electrical conduction. Furthermore, a severe reducing environment enables us to substitute electrons almost completely for anions in the cages, forming a stable inorganic electride. Finally, the formation of these active anions in this material is examined in terms of electronic structures, thermodynamics, and structural features of the cage.
    A cage structure in a positively charged lattice framework was utilized to incorporate and release chemically unstable anions. This approach imparted unique chemical and electronic activities to this material. Fullsize Image
BCSJ Award Article
  • Yoshiki Shimodaira, Hideki Kato, Hisayoshi Kobayashi, Akihiko Kudo
    2007 Volume 80 Issue 5 Pages 885-893
    Published: May 15, 2007
    Released: May 14, 2007
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    Chromium-replaced PbMoO4, PbMo1−xCrxO4, prepared by an aqueous reflux method, showed a photocatalytic activity for O2 evolution from an aqueous solution containing an electron accepter, such as Ag+ or Fe3+ under visible light irradiation (vis) (λ ≥ 420 nm). PbMo0.98Cr0.02O4 (Energy gap: 2.26 eV) showed the highest activity for the O2 evolution under vis and UV + vis light irradiation. The activity of PbMo0.98Cr0.02O4 was one order of magnitude higher than that of PbMoO4 under UV + vis light irradiation. The crystal structures of PbMo1−xCrxO4 were studied by the Rietveld analysis for powder X-ray diffraction. PbMo1−xCrxO4 had a scheelite-type structure when x was equal to or smaller than 0.2. The energy band structures of PbMo1−xCrxO4 were calculated based on density functional theory using the structural parameters refined by the Rietveld analysis. It was revealed that the top of the valence band of PbMoO4 consisted of O2p and Pb6s orbitals and the accepter level was composed of a Cr3d orbital in the forbidden band below the conduction band consisting of a Mo4d orbital. It was concluded that the visible light response was due to the excitation from the Pb6s + O2p valence band to the Cr3d accepter level.
    PbMo1−xCrxO4 exhibited visible light-driven photocatalytic activity for O2 evolution from an aqueous solution. On the basis of DFT calculations, the present study indicated that the formation of an electron-accepter level is one strategy for developing new visible light driven photocatalysts. Fullsize Image
 
  • Yoshimi Sueishi, Hideto Tobisako, Yashige Kotake
    2007 Volume 80 Issue 5 Pages 894-898
    Published: May 15, 2007
    Released: May 14, 2007
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    High static pressure was applied to the inclusion complex of a modified β-cyclodextrin, heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD), and the influence of O-methylation on the inclusion equilibrium was investigated. Guest molecules to be included by cyclodextrin were stable nitroxide radicals, α-substituted 2,4,6-trimethoxybenzyl(t-butyl)nitroxides. Each guest molecule had more than one bulky group that can form ESR-spectroscopically separable isomeric inclusion complexes. Previously, using selected nitroxide probes, group-inclusion equilibrium in DM-β-CD has been shown to be significantly altered as compared with unmodified β-CD. Thus, we investigated group-inclusion equilibria in DM-β-CD under high static pressure by employing high pressure ESR spectroscopy, and compared the data with that for unmodified β-CD. The reaction volume (ΔV) of the inclusion equilibrium, a unique parameter which is calculated only from pressure dependence data, showed a drastic shift in some DM-β-CD group-in complexes, such as cyclohexyl- and s-butyl-in complex. We concluded that the O-methylation mediated changes in the hydrophobic void space and the number of residual water molecules in the CD cavity are causal factors for the difference.
  • Akram A. Rousan, Ahmad M. Al-Ajlouni
    2007 Volume 80 Issue 5 Pages 899-901
    Published: May 15, 2007
    Released: May 14, 2007
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    The effect of applying an external magnetic field on the catalytic oxidation of indigo dyes with H2O2/imidazole was investigated. It was found that the rate of oxidation, in the presence of imidazole as a catalyst, was enhanced by applying an external magnetic field in the range of 0.035–0.12 T. The magnetic field did not affect the reaction in the absence of imidazole. A mechanism that involves radical intermediates is proposed.
  • Joe Otsuki, Izumi Kurihara, Arata Imai, Yuki Hamada, Nobuyuki Omokawa
    2007 Volume 80 Issue 5 Pages 902-909
    Published: May 15, 2007
    Released: May 14, 2007
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    The azobis(bipyridine) ligand 6,6″-azobis(2,2′-bipyridine) (6-azobpy) was prepared as a new member of the family of azopolypyridine derivatives. This compound undergoes reversible trans/cis photoisomerization. Reaction of 6-azobpy and [Ru(bpy)2Cl2] afforded a dinuclear complex [{Ru(bpy)2}2(μ-6-azobpy)]4+. An analogue with deuterated bpy fragments was also prepared to help clarify the 1H NMR signals in the part of the 6-azobpy ligand. The analysis of 1H NMR spectra clearly identified the structure of the complex, in which the Ru2+ ions are chelated by the bpy parts of the bridging 6-azobpy ligand. Electronic absorption and electrochemical properties are characterized by the presence of a low-lying π* level of the bridging ligand, manifested by a metal-to-ligand charge-transfer band extending down to 800 nm and by two consecutive one-electron reduction waves at relatively less negative potentials in cyclic voltammetry. These properties were compared with those of previously reported positional isomers with the help of density functional theory (DFT), time-dependent DFT, and ZINDO calculations. The analysis of the redox couple of Ru3+/2+ showed that the redox potentials differ slightly between the diastereomers and that there is an intermetallic electronic interaction.
  • Toru Takahashi, Yuka Takehara, Hitoshi Hoshino
    2007 Volume 80 Issue 5 Pages 910-915
    Published: May 15, 2007
    Released: May 14, 2007
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    The dissociation kinetics and the complexation equilibrium of a ZnII complex with 1,5-bis(2-hydroxy-5-sulfophenyl)-3-cyanoformazan (hscf: H5L) during capillary electrophoretic (CE) separation process were studied. The solvolytic dissociation reaction rate constants of the ZnII–hscf complex ([ZnL]3−) (kd) in the pH range of 6.4 to 8.0 were determined with a CE-based dissociation kinetic analysis method. Small kd values on the order of 10−5 s−1 showed the remarkable kinetic inertness of [ZnL]3−, which was detectable in the CE system. The stability constant of [ZnL]3− (KZnL) at 293 K and I = 0.10 was estimated to be [ZnL3−]/{[Zn2+][L5−]} = 1024.2±0.3 through the spectrophotometric titration. The thermodynamic stability of [ZnL]3− in the pre-capillary complexation stage was thus demonstrated. In contrast, it was shown that the CE separation environment is thermodynamically unsuitable for the metal complexes based on the conditional stability constant of [ZnL]3−, which was determined under CE separation conditions, and the concentration of free HSCF in the complex band in the capillary. Thus, the “stability” of metal complex in the CE system strongly depends on kinetic inertness rather than thermodynamic stability, though their thermodynamic stability is necessary for the pre-capillary derivatization step.
  • Hui Liang, Young Mee Na, In Sung Chun, Soon Sik Kwon, Young-A Lee, Ok- ...
    2007 Volume 80 Issue 5 Pages 916-921
    Published: May 15, 2007
    Released: May 14, 2007
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    Dinuclear 1,2-semiquinonato/catecholatocobalt complexes containing 1,1,4,7,10,10-hexamethyltriethylenetetramine (hmdeta) as a potential tetradentate N4 coligand, [Co2(hmteta)(dbbq)4], (dbbq = 3,5- and 3,6-di-tert-butyl-1,2-benzoquinone (3,5-dbbq and 3,6-dbbq)) were synthesized and characterized. The crystal structures proved that [Co2(hmteta)(3,6-dbbq)4]·2C6H5CH3 ([3,6]) exists as low spin [(3,6-dbsq)(3,6-dbcat)CoIII(hmteta)CoIII(3,6-dbsq)(3,6-dbcat)] (3,6-dbsq = 3,6-di-tert-butyl-1,2-semiquinonato; 3,6-dbcat = 3,6-di-tert-butylcatecholato), while [Co2(hmteta)(3,5-dbbq)4]·C6H5CH3 ([3,5]) approximates to [(3,5-dbsq)2CoII(hmteta)CoII(3,5-dbsq)2] in the solid state at ambient temperature. On the basis of the effective magnetic moments, the [CoIII] → [CoII] conversion of [3,6] underwent a relatively abrupt transition around 330 K while that of [3,5] occurs in a wide range of temperature. Electronic absorption spectra showed that [3,6] shifts predominantly to [CoIII] whereas [3,5] shifts to [CoII] valence tautomer in solution at room temperature. The charge distribution of [3,6] exhibited significant solvent effects at room temperature. These prominent features between [3,5] and [3,6] appeared to be associated with difference between delicate electronic and steric effects of the two dbbq ligands.
  • Mari Toyama, Ryuji Suganoya, Daisuke Tsuduura, Noriharu Nagao
    2007 Volume 80 Issue 5 Pages 922-936
    Published: May 15, 2007
    Released: May 14, 2007
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    The reaction between trans-[RuCl2(dmso-S)4] (dmso = dimethyl sulfoxide) and di-2-pyridylamine (Hdpa) in EtOH–H2O at ca. 273 K afforded trans(Cl),cis(S)-[RuCl2(Hdpa)(dmso-S)2] (1) in moderate to high yield. When dissolved in DMSO, 1 rearranged to the more thermodynamically stable cis(Cl),cis(S)-[RuCl2(Hdpa)(dmso-S)2] (2), along with cis(Cl),trans(X)-[RuCl2(Hdpa)(dmso)2] (X = S- or O-bonded dmso). The reaction of 2 with Ag(OTf) afforded cis(Cl,S),trans(O,S)-[RuCl(Hdpa)(dmso-O)(dmso-S)2](OTf) (3·(OTf)) (OTf = trifluoromethanesulfonate). X-ray crystal structures of 1, 2, and 3·(OTf) revealed that the conformation of the six-membered chelate ring formed by the Hdpa ligand with the Ru ion varies according to interactions among the co-ligands (dmso and Cl) and the counter-anion (OTf). For 3·(OTf), the structural parameters, apart from the dmso-O ligand, were essentially comparable to those of 2, except for the axial Cl ligand; the remaining axial site is occupied by the O-donor of the dmso ligand instead of the S-donor. The solution structures (in DMSO solution) of 1, 2, and 3·(OTf) are discussed on the basis of their 1H NMR spectra. In 3·(OTf), “flapping” of the Hdpa ligand causes the coordination modes (O- and S-bonded) of the two axial dmso ligands to undergo mutual alternation.
  • Mari Toyama, Makito Nakahara, Noriharu Nagao
    2007 Volume 80 Issue 5 Pages 937-950
    Published: May 15, 2007
    Released: May 14, 2007
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    The reaction between trans-[RuCl2(dmso-S)4] (dmso = dimethyl sulfoxide) and di-2-pyridyl ketone (dpk) in H2O at room temperature afforded trans(Cl),cis(S)-[RuCl2(dpk-κ2N,O)(dmso-S)2] (1) in high yield, while the reaction between cis(Cl),fac(S)-[RuCl2(dmso-S)3(dmso-O)] and dpk in EtOH–DMSO at reflux afforded cis(Cl),cis(S)-[RuCl2(dpk-κ2N,N′)(dmso-S)2] (2). Reaction of 1 with Ag+ and OH afforded the one-dimensional Ru–Ag coordination polymer trans(Cl),cis(S)-[AgRuCl2(dpk-OH-κ3N,O,N′)(dmso-S)2]n (3), which, as shown by X-ray crystallographic analysis, was in an “arrested” state of chloride ion abstraction. Reaction of 3 in DMSO afforded a mixture of two isomers containing dpk-OH-κ3N,O,N′: trans(Cl,O),cis(S)- and cis(Cl,O),cis(S)-[RuCl(dpk-OH-κ3N,O,N′)(dmso-S)2] (4a and 4b, respectively). The trans(Cl,O),cis(S)-isomer 4a was selectively synthesized by reaction of 1 with OH in H2O, while the cis(Cl,O),cis(S)-isomer 4b was selectively synthesized by reaction of 2 with OH in H2O. The isomerization reaction between 4a and 4b in DMSO solution was found to be reversible, and 4b was favored over 4a, with K4ab = [4b]/[4a] = 1.5 ± 0.1. The crystal structures of 1 and 2 showed that the geometry of the RuCl2(dmso-S)2 unit caused selective formation of the κ2N,O- and κ2N,N′-coordination modes of the dpk ligand. In 4a, the flexibility of the κ3N,O,N′-coordination mode of the (dpk-OH) ligand mitigates the steric hindrance caused by the RuCl(dmso-S)2+ unit.
  • Kazunori Saitoh, Shogo Naitoh, Miho Endo, Manami Washiya, Masami Shibu ...
    2007 Volume 80 Issue 5 Pages 951-956
    Published: May 15, 2007
    Released: May 14, 2007
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    An on-line electrochemical redox derivatization technique for enhancement of separation selectivity of HPLC using an electrolytic flow cell is presented. This HPLC system consists of two separation columns and a small electrolytic flow cell placed between them. A redox derivatization reaction proceeds in the electrolytic flow cell so that an analyte compound migrates in its original form in the first column, while it moves in its oxidized or reduced form in the second column. The selective separation of an analyte compound has been achieved, because redox reactions specific for the analyte in the electrochemical derivatization unit can be controlled by alteration of potential applied to the cell. A successful application of this method to the separation and determination of cobalt in a stainless steel is demonstrated.
  • Toshiyuki Moriuchi, Masahito Nishiyama, Tomohiko Beppu, Toshikazu Hira ...
    2007 Volume 80 Issue 5 Pages 957-959
    Published: May 15, 2007
    Released: May 14, 2007
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    4,8-Dihydroxyquinoline-2-carboxylic acid (1) possessing quinoline-N, hydroxy-O, and carboxy-O donor functions was demonstrated to serve as a tridentate ligand in the complexation with NH4VO3, affording the cis-dioxovanadium(V) complex 2. Each molecule of 2 was found to be packed in a hexagonal molecular arrangement through π–π interaction in the crystal packing, creating a channel cavity which was occupied by water molecules that form a one-dimensional water chain.
  • Wataru Kosaka, Tomohiro Nuida, Kazuhito Hashimoto, Shin-ichi Ohkoshi
    2007 Volume 80 Issue 5 Pages 960-962
    Published: May 15, 2007
    Released: May 14, 2007
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    A paramagnetic pyroelectric 3-dimensional cyano-bridged assembly, [{MnII(H2O)2}{MnII(pyrazine)(H2O)2}{MoIV(CN)8}]·4H2O (P21) was synthesized. This compound displayed second harmonic generation with a value of 6.0 × 10−11 esu.
  • Machiko Arakawa, Hiroshi Miyamae, Yutaka Fukuda
    2007 Volume 80 Issue 5 Pages 963-965
    Published: May 15, 2007
    Released: May 14, 2007
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    New mixed-ligand nickel(II) complexes containing β-diketonates and 1,2-bis(diphenylphosphino)ethane, [Ni(dike)(dppe)]X (X = BF4, ClO4, and NO3) were synthesized and characterized. Since the ligand field strength of the phosphorus donor is very strong, the complexes [Ni(dike)(dppe)]X studied in this work are as stable as the square-planar both in solid state and in solutions.
  • Kazunori Iida, Makoto Mitani, Chiaki Kuroda
    2007 Volume 80 Issue 5 Pages 966-971
    Published: May 15, 2007
    Released: May 14, 2007
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    Diels–Alder reaction of furanoeremophilan-6β-ol (petasalbin) and its synthetic analogue, 4-hydroxy-4,5,6,7-tetrahydrobenzofuran, was studied using N-ethyl- and N-phenylmaleimides as the dienophiles, affording corresponding adducts as mixtures of stereoisomers. The adduct of petasalbin and maleimide was also obtained when the latter compound was added to a crude extracted solution of Petasites japonicus var. giganteus. By using this method, it was estimated that the contents of unstable furanoeremophilan-10β-ol in L. cymbulifera is more than 32% of the extract.
  • Shigeaki Imazeki, Ryohiko Kinoshita, Takahiko Akiyama
    2007 Volume 80 Issue 5 Pages 972-978
    Published: May 15, 2007
    Released: May 14, 2007
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    Allylsilane bearing malonate moiety underwent intramolecular carbocyclization reaction by means of AlCl3-n-Bu3N to give silyl-substituted cyclopentanes in good yields.
  • Masahiko Bessho, Takao Kojima, Shuichi Okuda, Masayuki Hara
    2007 Volume 80 Issue 5 Pages 979-985
    Published: May 15, 2007
    Released: May 14, 2007
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    Gelatin hydrogels with various concentrations were cross-linked by the irradiation with 60Co γ-rays, and we investigated the radiation-induced cross-linking of gelatin hydrogels by estimating the physical properties of irradiated hydrogels. In case of the 1, 5, and 10% (w/v) gelatin solutions, the specific water content of the irradiated hydrogels, the index showing the extent of cross-linking depended on the absorbed dose, and that of the irradiated gelatin hydrogels with the lower concentration decreased drastically. The breaking strength correlated to the absorbed dose, irrespective of the initial gelatin concentration. More than 8 kGy irradiation induced insolubility due to the cross-linking of the gelatin hydrogels. Besides, γ-ray irradiation to gelatin with free amino acids revealed that amino acids, which have side chains of hydrocarbon groups that are more than two carbon atoms, obstructed the cross-linking of gelatin hydrogels. It is thought that the hydrocarbon groups, such as an alkyl or a phenyl group of the side chains, are the cross-linking sites of gelatin hydrogels.
  • Zhang-Jun Hu, Jia-Xiang Yang, Yu-Peng Tian, Xu-Tang Tao, Lei Tian, Hon ...
    2007 Volume 80 Issue 5 Pages 986-993
    Published: May 15, 2007
    Released: May 14, 2007
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    Efficient aqueous-phase aldol condensation, Michael addition, and solvent-free Wittig reactions were successfully employed to synthesize two two-photon initiators 9-ethyl-3-[4-(2,2′:6′,2″-terpyridinyl-4′-yl)styryl]carbazole (T1) and 9-{4-[4-(2,2′:6′,2″-terpyridinyl-4′-yl)styryl]phenyl}carbazole (T2). The two initiators with carbazolyl moiety attached to 2,2′:6′,2″-terpyridine present D–π–A-type framework, where A is a π-deficient terpyridine ring. The crystal structures were determined by single-crystal X-ray diffraction determination. The experimental results confirmed that the two initiators have sensitive single-photon-excited fluorescence (SPEF) and two-photon-excited fluorescence (TPEF) properties. The experimental and theoretical two-photon absorption (TPA) cross-sections were investigated. Two-photon initiation polymerization (TPIP) microfabrication experiments were carried out, and possible polymerization mechanisms are discussed based on the theoretical evaluation.
  • Huixia Wu, Yanghui Lin, Jiawei Tang, Dong Gao, Ruifang Cai, Dongyuan Z ...
    2007 Volume 80 Issue 5 Pages 994-998
    Published: May 15, 2007
    Released: May 14, 2007
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    A specific fullerene derivative, C60(CHCOOH)2, was introduced into the matrix network of well-ordered hexagonal mesoporous silica (SBA-15) via a chemical bond interaction. The methods included aminosilylation of the surface silanols within SBA-15 channels by 3-aminopropyl(trimethoxy)silane (APTS) and a subsequent amide reaction between amino groups of APTS/SBA-15 and carboxylic acids of C60(CHCOOH)2. The final material C60(CHCOOH)2/APTS/SBA-15 was confirmed by XRD, TEM, and BET techniques, FT-IR and UV–vis spectra. The [60]fullerene carboxylic derivative molecules were uniformly distributed in the channels of SBA-15, while pure [60]fullerene molecules remained as clusters or larger aggregate states.
  • Masaki Matsui, Takaya Maehashi, Kazumasa Funabiki
    2007 Volume 80 Issue 5 Pages 999-1003
    Published: May 15, 2007
    Released: May 14, 2007
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    Novel non-ionic near-infrared (NIR) fluorescent 2,3-dicyanopyrazines were prepared. 5-[6-(9-julolidyl)-1,3,5-hexatrienyl]- and 5-[8-(9-julolidyl)-1,3,5,7-octatetraenyl]-2,3-dicyanopyrazines showed fluorescence maxima (Fmax) at 716 and 751 nm with fluorescence quantum yields (Φf) 0.12 and 0.03 in toluene, respectively. MO calculations showed that these compounds have an intramolecular charge-transfer chromophoric system from the julolidyl to dicyanopyrazine moieties. The calculations also showed that since the HOMO energy level was unstabilized, and at the same time, the LUMO energy level was stabilized by expanding the conjugated system at 5-position, NIR fluorescent derivatives were obtained. They showed clear positive solvatochromism in the fluorescence spectroscopy. The fluorescence intensity drastically decreased in polar solvents.
  • Kazuhiko Maeda, Kentaro Teramura, Nobuo Saito, Yasunobu Inoue, Kazunar ...
    2007 Volume 80 Issue 5 Pages 1004-1010
    Published: May 15, 2007
    Released: May 14, 2007
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    Gallium nitride (GaN) powder was studied as a photocatalyst for overall water splitting. The photocatalytic activity of GaN for the reaction was found to be strongly dependent on the crystallinity of the material and the cocatalyst employed. Modification of well-crystallized GaN with Rh2−yCryO3 nanoparticles as a cocatalyst for H2 evolution resulted in the stable stoichiometric decomposition of H2O into H2 and O2 under ultraviolet irradiation (λ > 300 nm) by the band gap transition. RuO2 modification did not bring about appreciable H2 and O2 evolution. Low-crystallinity GaN exhibits negligible activity for overall water splitting, regardless of the kind of cocatalyst applied.
  • Toshio Itoh, Ichiro Matsubara, Woosuck Shin, Noriya Izu
    2007 Volume 80 Issue 5 Pages 1011-1016
    Published: May 15, 2007
    Released: May 14, 2007
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    Layered organic/inorganic hybrid thin film, which consist of MoO3 with poly(o-anisidine) (PoANIS), were investigated by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FE-SEM) analysis, and gas-sensing properties analysis. The MoO3 with PoANIS ((PoANIS)xMoO3) hybrid was prepared by an intercalation process, in which sodium ions were exchanged for PoANIS in MoO3 thin films. The laminated structure of the (PoANIS)xMoO3 hybrid was shown to have high periodic regularity by XRD analysis. The highly oriented (PoANIS)xMoO3 hybrid grains were observed on the substrate surface by XRD and FE-SEM analyses. The (PoANIS)xMoO3 hybrid had a large gas-sensing response to aldehydic gases, and little or no response to other volatile organic compounds. Moreover, the gas-sensing abilities of (PoANIS)xMoO3 were stronger for acetaldehyde than for formaldehyde, whereas other typical organic/MoO3 hybrids showed an opposite response, which can be explained by solubility parameter theory.
  • Mst. Shamsun Nahar, Kiyoshi Hasegawa, Shigehiro Kagaya, Shigeyasu Kuro ...
    2007 Volume 80 Issue 5 Pages 1017-1019
    Published: May 15, 2007
    Released: May 14, 2007
    JOURNALS RESTRICTED ACCESS
    The combined photocatalytic system (P25 TiO2 + Fe(ClO4)3) was visible light active, and the phenol degradation rate was higher than the sum of the rates for the separately used single photocatalyst. The reason is discussed based on the catalytic cycle of FeIII/FeII. The suspended TiO2 particles were easily sedimented by neutralizing the suspension.
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