Nihon Kessho Gakkaishi
Online ISSN : 1884-5576
Print ISSN : 0369-4585
ISSN-L : 0369-4585
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Volume 53, Issue 6
Displaying 1-14 of 14 articles from this issue
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Review Articles
  • Crystallographic Studies on the Mechanisms of the Cluster Formation and the Higher Order Structure Evolution of Mixed-valence Polyoxometalates
    Tomoji OZEKI
    2011 Volume 53 Issue 6 Pages 371-379
    Published: December 31, 2011
    Released on J-STAGE: January 18, 2012
    DOIhttps://doi.org/10.5940/jcrsj.53.371
    JOURNAL FREE ACCESS
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    The advantages of the use of synchrotron radiation for single crystal X-ray diffraction experiments were exploited to obtain a deeper understanding of the chemistry of polyoxometalates through structural investigations. The pH dependence of the structures of {Mo154-x} mixed-valence oxomolybdate clusters were investigated by analyzing the structures of systematically prepared compounds containing wheel-shaped mixed-valence polyoxometalates with 138, 142, 148, 150, or 152 molybdenum atoms. Direct correlation was observed between the nuclearity of the clusters with the pH of the mother liquor. On the other hand, the geometries of extended structures do not show apparent correlation with the pH. They turned out to be determined by the structures of the constituent polyoxometalate. The pH of the mother liquor exerts influence on the extended structure through the structures of the constituent clusters. Such systematic preparation—structure determination study was enabled by the use of synchrotron radiation.
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  • Development of an Accurate Crystal Structure Analysis Method Using Energy-Filtering Convergent-Beam Electron Diffraction
    Kenji TSUDA
    2011 Volume 53 Issue 6 Pages 380-386
    Published: December 31, 2011
    Released on J-STAGE: January 18, 2012
    DOIhttps://doi.org/10.5940/jcrsj.53.380
    JOURNAL FREE ACCESS
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    An accurate crystal structure analysis method has been developed using energy-filtering convergent-beam electron diffraction. Characteristic features of the method, the analysis procedure, some applications are described, together with future prospects.
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  • Static and Dynamic Structure Analyses of Polymer Crystals
    Kohji TASHIRO
    2011 Volume 53 Issue 6 Pages 387-395
    Published: December 31, 2011
    Released on J-STAGE: January 18, 2012
    DOIhttps://doi.org/10.5940/jcrsj.53.387
    JOURNAL FREE ACCESS
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    Recent development in static and dynamic structure analyses of polymer crystals has been reviewed. Various methods were developed to enhance the reliability of static structure analysis. Usage of synchrotron high-energy X-ray beam allowed us to increase the total number of observed X-ray reflections by one order. Wide-angle neutron diffraction revealed the hydrogen atomic positions accurately, making it possible to evaluate the mechanical property of polymer crystals quantitatively. Time-resolved measurements of wide-angle and small-angle X-ray scatterings as well as infrared and Raman spectra have revealed the structural revolution processes as seen in the studies of isothermal crystallization and mechanical deformation processes.
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Articles
  • Structure of the Flagellar Type III Export Chaperone FliT, and Its Regulatory Mechanism of Flagellar Assembly
    Katsumi IMADA, Tohru MINAMINO, Keiichi NAMBA
    2011 Volume 53 Issue 6 Pages 396-401
    Published: December 31, 2011
    Released on J-STAGE: January 18, 2012
    DOIhttps://doi.org/10.5940/jcrsj.53.396
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    Flagellar export chaperones are multifunctional small proteins required for efficient construction of the bacterial flagellum. FliT is a flagellar export chaperone for the filament-capping protein FliD. We have determined the structure of FliT at 3.2 Å resolution. FliT adopts an anti-parallel α-helical bundle structure with a unique C-terminal helical segment of flexible orientation. The structure and following genetic and biochemical studies indicated that a conformational change of the C-terminal segment is responsible for switching the binding partners to regulate gene expression and protein export. This finding reveals how the complex pattern of interactions with various binding partners is regulated by a conformational change of such a small protein molecule.
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  • Construction and Mechanistic Studies of Vapochromic Metal Complexes
    Atsushi KOBAYASHI, Masako KATO
    2011 Volume 53 Issue 6 Pages 402-408
    Published: December 31, 2011
    Released on J-STAGE: January 18, 2012
    DOIhttps://doi.org/10.5940/jcrsj.53.402
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    Recently, vapochromic materials have drawn increasing attention because of their promising vapor sensing functions. In this paper, from the viewpoint of structural chemistry, several types of vapochromic metal complexes are described. The first one is vapochromic materials composed of Pt (II)-diimine complexes in which the origin of vapochromic behavior is the modification of the intermolecular metallophilic interactions. Second are the materials utilizing porous frameworks to adsorb/desorb vapor molecules. Third is the vapochromic hydrogen-bonded proton-transfer assembly which can recognize the hydrogen-bonding ability of vapor molecules.
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  • Crystal Structure of Cobalt Oxide Superconductors and Their Short-Range-Order Stacking
    Mitsuko ONODA, Kazunori TAKADA, Takayoshi SASAKI
    2011 Volume 53 Issue 6 Pages 409-415
    Published: December 31, 2011
    Released on J-STAGE: January 18, 2012
    DOIhttps://doi.org/10.5940/jcrsj.53.409
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    Neutron powder diffraction patterns of 2H- and 3R-NaxCoO2·yD2O (x~0.35, y~1.3), which show superconductivity with Tc of about 4.7 K, show conspicuous diffuse maxima presumed to originate from the Na/D2O part in addition to sharp reflections due to the CoO2 part. The structure is treated as an interpenetration of two layered structures, the CoO2 part (a1=b1=2.82 Å) and the Na/D2O part (a2=b2=3.26 Å). A model of the short-range-order stacking of the Na/D2O part is expressed and diffuse scattering intensities simulated using the matrix method satisfactorily explain the neutron diffraction patterns. Information about atomic coordinates was obtained based on superstructure expression with A=B=2a1=a2√3=5.64 Å including short-range order stacking.
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Topics
  • How is Cd Incorporated in Biominerals Eliminated by Tobacco Trichomes?
    –Phase Identification of Calcium Carbonate by Micro-XRD and Micro-XANES
    Akiko HOKURA
    2011 Volume 53 Issue 6 Pages 416-418
    Published: December 31, 2011
    Released on J-STAGE: January 18, 2012
    DOIhttps://doi.org/10.5940/jcrsj.53.416
    JOURNAL FREE ACCESS
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    In tobacco plants, elimination of Zn and Cd via the production of Ca-containing grains at the top of leaf hairs, called trichomes, is a potent detoxification mechanism. When tobacco plants were grown in a nutrient solution containing an amount of Cd and low Ca supplement, most of the grains were oblong-shaped and low-Cd-substituted calcite. When exposed to the same amount of Cd and high Ca supplement, grains were more abundant and diverse in compositions, and in total more Cd was eliminated. Most grains in the high Ca/Cd experiment were round-shaped and composed predominantly of Cd-substituted vaterite, a usually metastable calcium carbonate polymorph, and subordinate calcite.
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