Mitsuhiko Shionoya

Massachusetts Institute of Technology, Cambridge, Massachusetts, United States

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Publications (173)912.55 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A macrocyclic host molecule possessing a nano-cavity with two AgI centers for guest binding and four anthracene walls has been developed. This dimetal-macrocycle forms stable inclusion complexes with ditopic aromatic guest molecules, [2.2]paracyclophane and ferrocene, in solution and/or in the solid state through Ag-π interactions within the nano-cavity. The binding constants for the inclusion complexes were found to range roughly from 104 to 109 M-1. Electrochemical measurement revealed that the oxidized form of the included cationic ferrocene was less stabilized due to the direct binding to the cationic two AgI centers.
    Journal of the American Chemical Society 12/2014; · 10.68 Impact Factor
  • Ryou Kubota, Shohei Tashiro, Motoo Shiro, Mitsuhiko Shionoya
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    ABSTRACT: Molecular adsorption is a fundamental phenomenon in porous materials and is usually characterized by the efficiency and selectivity of molecular separations and reactions. However, for functional porous materials, analysis of the dynamic behaviour of molecular adsorbents is a major challenge. Here, we use in situ single-crystal X-ray diffraction to analyse multi-step molecular adsorption in a crystalline nanochannel of a metal-macrocycle framework. The pore surface of the metal-macrocycle framework crystal contains five different enantiomerically paired binding pockets, to which the adsorption of a (1R)-1-(3-chlorophenyl)ethanol solution was monitored with time. The resulting X-ray snapshot analyses suggest that the guest adsorption process takes a two-step pathway before equilibrium, in which the guest molecule is temporarily trapped by a neighbouring binding site. This demonstrates the potential for using X-ray analyses to visualize a transient state during a non-covalent self-assembly process.
    Nature Chemistry 10/2014; 6(10):913-8. · 21.76 Impact Factor
  • Shohei Tashiro, Mitsuhiko Shionoya
    ChemInform 09/2014; 45(35).
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    ABSTRACT: A charge-transfer (CT) complex was formed between corannulene (C20H10) and lithium ion-encapsulated [60]fullerene (Li+@C60) with the binding constant KG = 1.9 × 10 M-1 by concave-convex π-π CT interactions in benzonitrile at 298 K, exhibiting a broad CT absorption extended to the NIR region. Femotosecond laser excitation of the C20H10/Li+@C60 CT complex resulted in the singlet charge-separated (CS) state, 1(C20H10•+/Li+@C60•-), which decayed with the lifetime of 1.4 ns. Nanosecond laser excitation of Li+@C60 resulted in intermolecular electron transfer (ET) from C20H10 to the triplet excited state of Li+@C60 [3(Li+@C60)*] to produce the triplet CS state 3(C20H10•+/Li+@C60•-). The distance between two electron spins in the triplet CS state was estimated to be 10 Å from the zero-field splitting pattern observed by EPR measurements at 4 K. The triplet CS state decayed to the ground state via intramolecular back electron transfer (BET) in the CS state. The CS lifetime was determined to be 240 μs in benzonitrile at 298 K. The temperature dependence of the rate constant of BET afforded the reorganization energy (λ = 1.04 eV) and the electronic coupling term (V = 0.0080 cm-1). The long lifetime of CS state results from the spin-forbidden BET process and a small V value.
    Journal of the American Chemical Society 08/2014; · 10.68 Impact Factor
  • Shohei Tashiro, Mitsuhiko Shionoya
    ChemInform 07/2014; 45(27).
  • Ryosuke Miyake, Mitsuhiko Shionoya
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    ABSTRACT: To understand reversible structural switching in crystalline materials, we studied the mechanism of reversible crystal-to-crystal transformation of a tetranuclear Ni(II) macrocycle consisting of artificial β-dipeptides. On the basis of detailed structural analyses and thermodynamic measurements made in a comparison of pseudo-isostructural crystals (NO3 and BF4 salts), we herein discuss how ligand-exchange reactions take place in the crystal due to changes in water content and temperature. Observations of the structural transformation of NO3 salt indicated that a pseudo crystalline phase transformation takes place through concerted ligand-exchange reactions at the four Ni(II) centers of the macrocycle with hydrogen bond switching. A mechanism for this ligand exchange was supported by IR spectroscopy. Thermodynamic measurements suggested that the favorable compensation relationship of the enthalpy changes due to water uptake and structural changes are keys to the reversible structural transformation. On the basis of a comparison with the pseudo-isostructural crystals, it is apparent that the crystal packing structure and the types of counter anions are important factors for facilitating reversible ligand exchange with single crystallinity.
    Inorganic chemistry. 06/2014; 53(11):5717-23.
  • Shohei Tashiro, Tsutomu Umeki, Ryou Kubota, Mitsuhiko Shionoya
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    ABSTRACT: Porous crystals are excellent materials with potential spatial functions through molecular encapsulation within the pores. Co-encapsulation of multiple different molecules further expands their usability and designability. Herein we report the simultaneous arrangement of up to three different guest molecules, TTF (tetrathiafulvalene), ferrocene, and fluorene, on the pore surfaces of a porous crystalline metal-macrocycle framework (MMF). The position and orientation of adsorbed molecules arranged in the pore were determined by single-crystal X-ray diffraction analysis. The anchoring effect of hydrogen bonds between the hydroxy groups of the guest molecules and inter-guest cooperation and competition are significant factors in the adsorption behaviors of the guest molecules. This finding would serve as a design basis of multicomponent functionalized nanospaces for elaborate reactions that are realized in enzymes.
    Angewandte Chemie International Edition in English 05/2014; · 13.45 Impact Factor
  • Shohei Tashiro, Tsutomu Umeki, Ryou Kubota, Mitsuhiko Shionoya
    [Show abstract] [Hide abstract]
    ABSTRACT: Porous crystals are excellent materials with potential spatial functions through molecular encapsulation within the pores. Co-encapsulation of multiple different molecules further expands their usability and designability. Herein we report the simultaneous arrangement of up to three different guest molecules, TTF (tetrathiafulvalene), ferrocene, and fluorene, on the pore surfaces of a porous crystalline metal–macrocycle framework (MMF). The position and orientation of adsorbed molecules arranged in the pore were determined by single-crystal X-ray diffraction analysis. The anchoring effect of hydrogen bonds between the hydroxy groups of the guest molecules and inter-guest cooperation and competition are significant factors in the adsorption behaviors of the guest molecules. This finding would serve as a design basis of multicomponent functionalized nanospaces for elaborate reactions that are realized in enzymes.
    Angewandte Chemie 05/2014;
  • Elizabeth M Nolan, Mitsuhiko Shionoya
    Current opinion in chemical biology 04/2014; · 8.30 Impact Factor
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    ABSTRACT: Coordination-driven self-assembly utilizing labile capping ligands has been exploited as a novel strategy for metallo-cage containers. Herein, we report a tetrameric porphyrin barrel complex [C60⊂Zn814(H2O)4(OTs)12](OTs)4 (2) (OTs = p-CH3C4H6SO3) formed from a tetrakis(bipyridyl)porphyrin ligand 1, Zn(OTs)2, and a template guest, C60 fullerene. The tetrameric-barrel 2 contains two kinds of bis(bpy) ZnII centers coordinated by TsO- anions which serve as labile capping ligands in the formation of the finite structure of 2.
    Journal of the American Chemical Society 12/2013; · 10.68 Impact Factor
  • Takashi Nakamura, Hitoshi Ube, Mitsuhiko Shionoya
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    ABSTRACT: Guests welcome: Complex formation between Ag(I) ions and a Zn-porphyrin ligand (L) possessing four 2,2'-bipyridyl groups produced a dimeric complex [Ag4 L2 ](4+) , wherein the interplane distance between the Zn-porphyrin groups was ideal for intercalation of aromatic molecules through π-π interactions. The cofacial dimer [Ag4 L2 ](4+) serves as an excellent receptor for π-electron-deficient guests.
    Angewandte Chemie International Edition 09/2013; · 11.34 Impact Factor
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    ABSTRACT: The syntheses and properties of corannulenes carrying electron-withdrawing groups (F, CF3, C6F5 ) are reported. Direct fluorination of corannulene (C20H10) was carried out with xenon difluoride, and the crystal structure of the product was confirmed by the X-ray analysis. Novel trifluoromethylated corannulenes, including the versatile 4,9-dibromo-1,2-bis(trifluoromethyl)corannulene, were obtained by various established ring-closing reactions. Besides the use of hexafluorobutyne for the construction of fluoranthenes by Diels-Alder reaction as precursor molecules to form 1,2-disubstituted corannulenes, bis(pentafluorophenyl)acetylene was employed as dienophile. The molecular structure and crystal packing of a trifluoromethylated corannulene was determined by single-crystal X-ray analysis and compared with those known brominated and trifluoromethylated corannulenes. The general electron-acceptor properties of corannulenes bearing substituents introduced in particular positions by liquid-phase synthesis are discussed together with published computational results.
    Chemistry - A European Journal 09/2013; · 5.93 Impact Factor
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  • Shohei Tashiro, Ryou Kubota, Minori Kawagoe, Mitsuhiko Shionoya
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    ABSTRACT: Synthetic amphiphiles have been found to self-assemble into a variety of structures such as micelles, vesicles, cylinders and lamellae in aqueous media over many length scales. We report herein cation-induced aggregation of hexaaza-cyclophanes in water. Pd(2+)- or proton-induced formation of submicro spherical aggregates was observed by several spectroscopic and microscopic methods.
    Dalton Transactions 08/2013; · 4.10 Impact Factor
  • Takashi Nakamura, Hitoshi Ube, Mitsuhiko Shionoya
    ChemInform 07/2013; 44(30).
  • Masumi Kuritani, Shohei Tashiro, Mitsuhiko Shionoya
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    ABSTRACT: Stacked rings: A diamond-shaped macrocycle with two inward phenanthroline ligands and outward long alkyl chains, and its Pd(II) complex form organic and organometallic fibrous aggregates, respectively, as revealed by NMR, UV/Vis, AFM, and TEM measurements. The most likely structures are face-to-face stacked macrocycles, generating nanotubes.
    Chemistry - An Asian Journal 03/2013; · 4.57 Impact Factor
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    ABSTRACT: Bowl-shaped corannulene provides various metal binding modes with its curved π-surfaces and rim. Herein, we report the syntheses of 2-pyridylcorannulene and its cyclopalladated complex. Its expanded π-system and columnar self-assembly in the crystal state were revealed by NMR and UV-vis spectroscopies, ESI-TOF mass spectrometry and single-crystal X-ray analysis.
    Dalton Transactions 01/2013; · 4.10 Impact Factor
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    ABSTRACT: Macrocyclic compounds that can bind cationic species efficiently and selectively with their cyclic cavities have great potential as excellent chemosensors for metal ions. Recently, we have developed a tetraoxime-type tetraazamacrocyclic ligand 1 formed through a facile one-pot cyclization reaction. Aiming to explore and bring out the potential of the tetraoxime macrocycle 1 as a chelating sensor, we report herein the preparation of several kinds of silver complexes of 1 and their unique coordination structures determined by single-crystal X-ray diffraction analyses. As a result, the formation of two kinds of discrete structures, monomeric complexes [Ag(1)X] (X = counter anions) and a dimeric complex [Ag2(1)2]X2, and two kinds of polymeric structures from a mononuclear complex, [Ag(1)]nXn, and from a dinuclear complex, [Ag2(1)X2]n, was demonstrated. In the resulting complexes, the structurally flexible macrocyclic ligand 1 was found to provide several different coordination modes. Notably, in some silver complexes of 1, AgI-AgI interactions were observed with different AgI-AgI distances which depend on the kind of counter anions and the chemical composition.
    Sensors 01/2013; 13(5):5671-85. · 2.05 Impact Factor
  • Jean-Louis H A Duprey, Yusuke Takezawa, Mitsuhiko Shionoya
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    ABSTRACT: Three-way split: A postsynthetic click reaction has resulted in the conjugation of three bipyridine ligands at the core of a DNA three-way junction structure. Melting curve analyses revealed that Ni(II) ions significantly stabilize the junction structure through the formation of a [Ni(bpy)(3) ](2+) complex which cross-links three strands. The metal complex shows a diastereomeric preference, thus indicating a chirality transfer from the DNA.
    Angewandte Chemie International Edition 12/2012; · 11.34 Impact Factor
  • Ryou Kubota, Shohei Tashiro, Tsutomu Umeki, Mitsuhiko Shionoya
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    ABSTRACT: Recently, we have reported a metal-macrocycle framework (MMF) with five enantiomerically paired molecular binding pockets that exhibit site-selective guest arrangement on the nano-channel surface in soaking experiments using a variety of guest molecules. The guest inclusion is based largely on molecular exchange between solvent molecules such as CH3CN and guest molecules on the surface. Herein, we report that the molecular arrangement on the nano-channel surface varies with size, shape and/or chemical properties of functional groups of guests, mono-substituted benzene derivatives, such as benzonitrile, acetophenone and nitrobenzene. In their inclusion complexes, polar nitrile, acetyl and nitro groups serve as molecular anchors to a macrocyclic cavity through hydrogen bonding. Notably, benzonitrile and benzenesulphonic acid bind only to one pair of enantiomeric binding pockets. Such a highly site-selective binding would enable further multi-component surface modifications in the MMF.
    Supramolecular Chemistry 12/2012; 24(12). · 1.55 Impact Factor

Publication Stats

1k Citations
912.55 Total Impact Points

Institutions

  • 2014
    • Massachusetts Institute of Technology
      Cambridge, Massachusetts, United States
  • 1999–2014
    • The University of Tokyo
      • • Department of Chemistry
      • • Faculty of Science and Graduate School of Science
      Edo, Tōkyō, Japan
    • Kumamoto University
      • Department of Clinical Pharmaceutical Sciences
      Kumamoto, Kumamoto Prefecture, Japan
  • 2012
    • Ochanomizu University
      • Graduate School of Humanities and Sciences
      Tokyo, Tokyo-to, Japan
  • 2010–2012
    • Georg-August-Universität Göttingen
      • Institute of Inorganic Chemistry
      Göttingen, Lower Saxony, Germany
    • Nankai University
      • Department of Chemistry
      T’ien-ching-shih, Tianjin Shi, China
  • 2011
    • Peking University
      • College of Chemistry and Molecular Engineering
      Beijing, Beijing Shi, China
  • 2007
    • Nagoya University
      • Department of Chemistry
      Nagoya-shi, Aichi-ken, Japan
  • 1991–2002
    • Hiroshima University
      • • Department of Dental and Medical Biochemistry
      • • School of Medicine
      Hirosima, Hiroshima, Japan
  • 2000
    • The Graduate University for Advanced Studies
      Миура, Kanagawa, Japan
  • 1998
    • Institute for Molecular Science
      Okazaki, Aichi, Japan