日本結晶学会誌
Online ISSN : 1884-5576
Print ISSN : 0369-4585
ISSN-L : 0369-4585
55 巻 , 1 号
選択された号の論文の21件中1~21を表示しています
特集 結晶学による化学反応の可視化
1.原子・分子の動きの可視化
  • 星野 学
    2013 年 55 巻 1 号 p. 2-6
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    Molecular structure of an organic photocatalist, 9-mesityl-10-methylacrinium cation, at a photo-induced electron-transferred state was directly observed by a pump-probe single crystal X-ray structure analysis. Observed photo-induced structural changes were the bending of the N-methly group and the positional change of perchrolate anion, which co-exists in the crystal. Those structural changes respectively represented the reduction of the 10-methylacridinium cation and the oxidation of the mesitylene by photo-induced electron transfer. The dyhedral angle betweem 10-methylacridinium and mesitylene moieties at the electron-transferred state was almost identical with the ground one. This is a clear evidence for restriction of intramolecular back electron transfer and long-lived character of the electron-transferred state. The observed geometrical features will provide a solid basis for designing a novel artificital photosynthetic system.
  • 河野 正規
    2013 年 55 巻 1 号 p. 7-13
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    This account describes the development of direct observation of unstable species and chemical reactions in single crystals by X-rays. The methodology was developed by three steps: utilization of 1) the crystal packing of target molecules, 2) a void of a cage compound (a prison cell approach), and 3) a pore of coordination networks (a crystalline molecular flask approach). Using these strategies, we succeeded in observing radical, nitrene, carbene, a 2+2 reaction, condensation reactions, imine, hemiaminal, and so on. Noteworthy is that, using a porous coordination network as a nano-meter sized flask, various chemical reactions can be directly observed by X-rays. The crystalline molecular flask concept can be a general method to observe many kinds of chemical processes.
  • 佐藤 篤志
    2013 年 55 巻 1 号 p. 14-18
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    Time-resolved X-ray absorption spectra was conducted to investigate transient structure change in the triplet metal-to-ligand charge transfer (3MLCT) state of ruthenium(II)-tris-2,2'-bipyridine ([RuII(bpy)3]2+). The results obtained by visible (400 nm) and UV (267 nm) excitation indicates that electrostatic interaction between the oxidized Ru atom and the reduced bipyridine ligand are the dominant factors affecting the Ru-N bond contraction. The EXAFS analysis of the 3MLCT state shows decrease of Ru-N distance and increase of Debye-Waller (DW) factor. An increase of the DW factor suggests that fast and localized structural distortions due to electron hopping exist in the 3MLCT excited state.
  • 原田 潤
    2013 年 55 巻 1 号 p. 19-23
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    This review introduces pedal motion of molecules in crystals, where a pair of benzene rings in a molecule move like the pedals of a bicycle. The pedal motion brings about conformational interconversions, which result in disordered crystal structures. This type of molecular motion takes place in a wide range of compounds. This review describes how to investigate molecular motions using X-ray diffraction analysis, especially focusing on disorder analysis as a function of temperature.
  • 苙口 友隆, 池口 満徳, 佐藤 衛
    2013 年 55 巻 1 号 p. 24-31
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    The combination of small-angle X-ray solution scattering (SAXS) experiments and molecular dynamics (MD) simulations is now becoming a powerful tool to study protein dynamics in solution at an atomic resolution. We have developed a method called MD-SAXS, in which this combination is used with explicit evaluation of X-ray scattering from water molecules hydrating protein molecules. This method offers a link between low-resolution structural information from SAXS and the three-dimensional high-resolution structure. The study using MD-SAXS method revealed the importance of intrinsic dynamics of DNA-binding protein EcoO109I in its function.
2.反応機構の可視化
3.可視化に立脚した反応設計・反応制御
  • 関根 あき子
    2013 年 55 巻 1 号 p. 58-62
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    Photochromism is reversible change of color by photoirradiation. In recent years, photochromic compounds have been attracting considerable attention of the chemists because of their potential application in optical memory media and optical switching devices etc. However, photochromic property such as the lifetime of the colored species depends on the crystal structure of the compounds, therefore it is difficult to control. Here we designed new hybrid cobalt complexes with photochromic compounds and show the dynamical change of the color fading rate of photochromic compounds by structural change with photoisomerization of alkyl group of the complexes in the crystalline-state.
  • 山田 眞二
    2013 年 55 巻 1 号 p. 63-68
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    Exposure of 4-methoxyazachalcone (1) with a head-to-head orientation to HCl gas produced the corresponding HCl salt with a head-to-tail stacked arrangement, which was confirmed by PXRD experiments. A plausible mechanism for the reorientation was proposed, in which cation-π interaction plays a key role during the processes. Irradiation of the produced salt afforded synHT dimer in high regio- and stereoselectivities, thus showing the effectiveness of the cascade process in crystals. Photodimerization of styrylpyridine (5) and 5·HCl·2H2O was also investigated. While 5 was photo-stable, irradiation of 5·HCl·2H2O gave synHT dimer in high selectivity. X-ray structural analysis of 5·HCl·2H2O clarified that water molecules assist the assembly of the molecules in a head-to-tail and face-to-face fashion through N-H⋅⋅⋅O hydrogen bonds in combination with cation-π interactions between the pyridinium and aromatic rings. Dehydration of 5·HCl·2H2O produced anhydrous 5·HCl, which was also photo-stable. This was rehydrated to produce 5·HCl·2H2O by exposure to H2O vapor.
  • 黒田 玲子
    2013 年 55 巻 1 号 p. 69-74
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    Molecular rearrangement and reactions occur between crystals spontaneously or by mechanical methods by way of molecular diffusion, cleavage and creation of hydrogen bonds or formation of co-ordination bonds, while retaining the memory of original crystal structures. Therefore, crystals thus formed in the solid state are often different from those obtained from conventional solution crystallization. Photocyclization of 2-(o-substuted-arylthio)-3-methyl-2-cyclohexene-1-ones within a crystal is influenced by external heavy-atom effect, and affords unique reaction products. By placing reactant molecules in a different environment by way of co-crystal formation, we could switch reaction pathways and hence product distribution in the solid state.
  • 植村 卓史
    2013 年 55 巻 1 号 p. 75-80
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    Recently, crystalline metal complexes with regular nanochannel structures have been extensively studied. The characteristic features of these metal complexes are controllable channel structures approximating molecular dimensions, designable pore surface functionality, and flexible frameworks responsive to guest molecules. Owing to these advantages, successful applications range from molecular storage/separation to heterogeneous catalysts. In particular, use of their tunable nanochannels for polymer chemistry can allow precision polymer synthesis and unique polymer confinement. This review article discusses promising approaches to multiple controls of polymer structures, analysis systems for low-dimensional polymer assemblies, and the construction of functional polymer nanohybrid materials.
  • 安部 聡, 上野 隆史
    2013 年 55 巻 1 号 p. 81-85
    発行日: 2013/02/28
    公開日: 2013/03/07
    ジャーナル フリー
    In recent years, protein crystals receive much attention in the filed of nanobiomaterial sciences because they consist of highly ordered protein assemblies with unique nano reaction environments. Therefore, protein crystals have been utilized as nanosized porous materials for application in separation processes, heterogeneous catalysis, drug delivery, and so on. These crystals are able to capture and deposit metal ions and metal complexes within solvent channels because the amino acid side chains responsible for coordinating the metal ions are periodically aligned on the surface of solvent channels of the crystal lattices. Here, we elucidate accumulation process of metals by X-ray crystallographic analysis of protein crystals containing metal complexes or ions and apply to catalytic reactions and preparation of magnetic materials.
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