研究者データベース

小西 克明(コニシ カツアキ)
地球環境科学研究院 物質機能科学部門 分子材料化学分野
教授

基本情報

所属

  • 地球環境科学研究院 物質機能科学部門 分子材料化学分野

職名

  • 教授

学位

  • 博士(工学)(東京大学)

ホームページURL

J-Global ID

研究キーワード

  • 超分子化学   有機・無機ハイブリッド   金属クラスター   Orgrnic - lnorganic hybrid   Metal Clrster   

研究分野

  • ナノテク・材料 / エネルギー化学
  • ナノテク・材料 / 複合材料、界面
  • ナノテク・材料 / 機能物性化学
  • ナノテク・材料 / 高分子化学
  • ナノテク・材料 / 有機合成化学
  • ナノテク・材料 / ナノ構造物理
  • ナノテク・材料 / ナノ構造化学
  • 環境・農学 / 環境材料、リサイクル技術
  • 環境・農学 / 環境負荷低減技術、保全修復技術

職歴

  • 2008年10月 - 現在 北海道大学 大学院地球環境科学研究院 教授
  • 2000年 - 2008年09月 Associate Professor, Hokkaido University
  • 2000年10月 - 2003年09月 JST PRESTO (さきがけ) 変換と制御 Researcher
  • 2000年 - 2003年 JSTさきがけ研究 研究員
  • 2000年 - 2002年 北海道大学 助教授(准教授)
  • 2000年 - 2000年 東京大学工学部 講師
  • 1991年 - 2000年 東京大学工学部 助手
  • 1991年 - 2000年 Research Associate, faculty of Engineering.

学歴

  •         - 1991年   東京大学   工学系研究科   合成化学
  •         - 1991年   東京大学
  •         - 1987年   東京大学   工学部   工業化学科
  •         - 1987年   東京大学

所属学協会

  • 高分子学会   日本化学会   The Society of Synthetic Organic Chemistry, Japan   The Society of Polymer Science, Japan   Chemical society of Japan   

研究活動情報

論文

  • Taniguchi Tohru, Suzuki Takahiro, Satoh Haruka, Shichibu Yukatsu, Konishi Katsuaki, Monde Kenji
    Journal of the American Chemical Society 140 46 15577 - 15581 2018年 [査読有り][通常論文]
  • Konishi Katsuaki, Iwasaki Mitsuhiro, Shichibu Yukatsu
    Accounts of Chemical Research 51 12 3125 - 3133 2018年 [査読有り][通常論文]
  • Sugiuchi Mizuho, Shichibu Yukatsu, Konishi Katsuaki
    Angewandte Chemie-International Edition 57 26 7855 - 7859 2018年 [査読有り][通常論文]
  • Mizuho Sugiuchi, Junichi Maeba, Nobuyuki Okubo, Munetaka Iwamura, Koichi Nozaki, Katsuaki Konishi
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 139 49 17731 - 17734 2017年12月 [査読有り][通常論文]
     
    Aggregation-induced optical responses are ubiquitous among a wide range of organic and inorganic compounds. Here, we demonstrate an unprecedented effect of aggregation on the photoluminescence (PL) profiles of [core + exo]-type [Au-8](4+) clusters, which displayed a change in the dominant PL emission mode from fluorescence to phosphorescence-type upon aggregation. In solvents in which cluster molecules are highly soluble and exist as monomers, they displayed single PL bands at similar to 600 nm at ambient temperatures. However, in solvents in which cluster molecules are less soluble and cluster aggregation is induced, a new PL band at similar to 700 nm also emerged. Lifetime measurements revealed that the PL emissions at similar to 600 and similar to 700 nm had fluorescence and phosphorescence characters, respectively. Studies of the excitation spectra suggested that organized cluster assemblies were responsible for the lower-energy emission at similar to 700 nm and had exceptionally high emission activity. Accordingly, intense phosphorescence-type emissions were observed in the solid state in which the quantum efficiencies were higher by two orders of magnitude than those of the corresponding monomeric forms in solution. This work provides an example of the critical effects of cluster aggregation events on their optical properties and shows the potential of such effects in the design of cluster based materials with unique functions and properties.
  • Md. Abu Bakar, Mizuho Sugiuchi, Mitsuhiro Iwasaki, Yukatsu Shichibu, Katsuaki Konishi
    NATURE COMMUNICATIONS 8 2017年09月 [査読有り][通常論文]
     
    It is well known that various transition elements can form M center dot center dot center dot H hydrogen bonds. However, for gold, there has been limited decisive experimental evidence of such attractive interactions. Herein we demonstrate an example of spectroscopically identified hydrogen bonding interaction of C-H units to Au atoms in divalent hexagold clusters ([Au6](2+)) decorated by diphosphine ligands. X-ray crystallography reveals substantially short Au-H/Au-C distances to indicate the presence of attractive interactions involving unfunctionalized C-H moieties. Solution H-1 and C-13 NMR signals of the C-H units appear at considerably downfield regions, indicating the hydrogen-bond character of the interactions. The Au center dot center dot center dot H interactions are critically involved in the ligand-cluster interactions to affect the stability of the cluster framework. This work demonstrates the uniqueness and potential of partially oxidised Au cluster moieties to participate in non-covalent interaction with various organic functionalities, which would expand the scope of gold clusters.
  • Katsuaki Konishi, Mitsuhiro Iwasaki, Mizuho Sugiuchi, Yukatsu Shichibu
    JOURNAL OF PHYSICAL CHEMISTRY LETTERS 7 21 4267 - 4274 2016年11月 [査読有り][通常論文]
     
    Recent advances in the crystal structure determination of ligand-protected metal clusters have revealed that their electronic structures and optical features are essentially governed by the nuclearity and geometries of the inorganic frameworks. In this Perspective, we point out the definite effects of the exterior ligand moieties on the properties of small gold clusters. On the basis of systematic experimental studies on the optical properties of Au-8 and Au-13 clusters with various anionic ligands, it was shown that not only the "through-bond" electronic effects of coordinating atoms but also the nonbonding interaction with neighboring heteroatoms and the electronic coupling with pi-systems cause substantial perturbations. We also suggest that the steric rigidity of the ligand environments affects their photoluminescence efficiencies. These findings imply the feasibility of the facile modulation of the cluster properties through the appropriate choice of ligand modules, which may lead to the evolution of novel cluster-based materials with unique properties and functions.
  • Yukatsu Shichibu, Keisuke Yoshida, Katsuaki Konishi
    INORGANIC CHEMISTRY 55 18 9147 - 9149 2016年09月 [査読有り][通常論文]
     
    The inclusion of a Ag-I ion by a hexanuclear platinum(II) thiolate macrocycle in solution was demonstrated, and the inclusion structure was determined by Xray crystallography. Unique host-guest intermetallic interactions driven by charge transfer were elucidated by optical absorption spectroscopy and theoretical calculations.
  • Mitsuhiro Iwasaki, Naoki Kobayashi, Yukatsu Shichibu, Katsuaki Konishi
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 18 28 19433 - 19439 2016年07月 [査読有り][通常論文]
     
    In the recent development of structurally defined ligand-stabilized gold clusters, it has been revealed that not only the inorganic units but also the surrounding organic ligands substantially affect their electronic/optical properties. In this work, a series of core + exo type Au-8 clusters decorated by dppp (Ph2P(CH2)(3)PPh2) and arylthiolate ligands ([Au-8(dppp)(4)(SR)(2)](2+), 1-5) were synthesized, and their optical properties were studied in order to gain insights into the perturbation effects of the organic ligands. 1-5 showed visible absorption and photoluminescence emission bands at longer wavelengths compared to their chloro-and acetylide-modified analogues, suggesting the contribution of weak non-bonding interactions of the Au framework with the ligand heteroatoms. Upon acid treatment, 2- and 4-pyridinethiolate clusters (R = Py, 2 and 4) showed larger red shifts of the absorption and emission bands than the 3-pyridyl isomer (3), implying the involvement of the resonance structures of the SPy units. On the other hand, all regioisomers (2-4) showed large photoluminescence enhancements upon pyridine protonation. X-ray crystallographic and NMR analyses of 4 and its protonated form (4') showed that the electron-deficient pyridinium rings of 4' form p-stacks with neighbouring phenyl groups of dppp, suggesting that the orientation of the surface aromatics is a plausible factor governing the emission efficiency. These observations provide examples of successful modulation of optical properties of small gold clusters through the electronic and/or steric perturbation by the proximal organic ligands, highlighting the importance of the ligand design in the fine tuning of cluster properties directed for optical chemosensors and luminescent materials.
  • Tohru Taniguchi, Mai Asahata, Akihito Nasu, Yukatsu Shichibu, Katsuaki Konishi, Kenji Monde
    CHIRALITY 28 7 534 - 539 2016年07月 [査読有り][通常論文]
     
    Separation of the diastereomers of glycosyl sulfoxides differing in the sulfur chirality has been difficult. This article presents a fast and scalable method for their diastereoseparation using a chiral stationary phase. The usefulness of this method was demonstrated in a 500-mg scale separation within 20 min, and in the separation of trisaccharyl sulfoxide diastereomers. (C) 2016 Wiley Periodicals, Inc.
  • Satoshi Wada, Yuichi Kitagawa, Takayuki Nakanishi, Koji Fushimi, Yasuhiro Morisaki, Koji Fujita, Katsuaki Konishi, Katsuhisa Tanaka, Yoshiki Chujo, Yasuchika Hasegawa
    NPG ASIA MATERIALS 8 2016年03月 [査読有り][通常論文]
     
    The chiral nonanuclear Tb(III) clusters [Tb-9(sal-(R)-Bt)(16)(mu-OH)(10)]+[NO3]-(Tb-(R)-Bt: sal-(R)-Bt=(R)-2-butyl salicylate) and [Tb9 (sal-(S)-Bt)(16)(mu-OH)(10)](+)[NO3](-)(Tb-(S)-Bt: sal-(S)-Bt=(S)-2-butyl salicylate) were found to exhibit a unique magneto-optical property: the Faraday effect. The clusters were composed of 9 Tb(III) ions bridged by 10 mu-OHs and 16 chiral salicylic acid esters. The Faraday rotation angle of Tb-(R)-Bt was greater than that of Tb-(S)-Bt, indicating that the Faraday effect was affected by the chirality of the Tb(III) clusters. The chiroptical properties of the Tb(III) clusters were estimated using circular dichroism and circularly polarized luminescence. In this study, a new finding concerning chiral magneto-optical properties was investigated.
  • Prashant G. Gudeangadi, Takeshi Sakamoto, Yukatsu Shichibu, Katsuaki Konishi, Tamaki Nakano
    ACS MACRO LETTERS 4 9 901 - 906 2015年09月 [査読有り][通常論文]
     
    (R)-1,1'-Bi(2-naphthol) was reacted with 1,4-phenylene diisocyanate leading to a mixture of linear polyurethane and cyclic compounds including a cyclic dimer and a cyclic trimer. The structure of the cyclic dimer was elucidated by X-ray crystal structure analysis. The polymer was proposed to possess a rather stiff, pi-stacked, 2/1-helical conformation on the basis of NMR, CD, and UV spectra and molecular dynamics simulations. The conformation was stable in the range of temperature of 0-60 degrees C.
  • Yutaro Kamei, Neil Robertson, Yukatsu Shichibu, Katsuaki Konishi
    JOURNAL OF PHYSICAL CHEMISTRY C 119 20 10995 - 10999 2015年05月 [査読有り][通常論文]
     
    Electronic properties of ultrasmall gold clusters with defined nuclearity and geometrical structures have been a recent subject of interest not only with respect to the concept of molecularity but also because of their potential applicability as nanomaterials and catalysts. In this work, the electrochemical properties of dppp-protected octagold clusters ([Au8L4](n+) (L = dppp, n = 2 (1) and 4 (2), dppp = Ph2P(CH2)(3)PPh2) with charge-dependent geometrical structures were investigated. Unlike conventional spherelike centered clusters held by multiple spokes, the nonspoked Ails clusters displayed irreversible electrochemical profiles for the two-electron redox interconversion between 1 and 2, exhibiting a wide energy gap between the redox couples. This electrochemical irreversibility could be attributed to the significant alteration of electronic structures associated with the redox-coupled isomerization of the nonspoked cluster structures. In addition, we show that the coordinative interaction of Cl- anions with the Au-8 clusters notably affects both reduction and oxidation courses, providing an example of coordination-coupled electron transfer events.
  • Naoto Fukunaga, Katsuaki Konishi
    NANOSCALE 7 48 20557 - 20563 2015年 [査読有り][通常論文]
     
    Poly(ethylene glycol) (PEG) has been widely used for the surface protection of inorganic nanoobjects because of its virtually 'inert' nature, but little attention has been paid to its inherent electronic impacts on inorganic cores. Herein, we definitively show, through studies on optical properties of a series of PEG-modified Cd10Se4(SR)10 clusters, that the surrounding PEG environments can electronically affect the properties of the inorganic core. For the clusters with PEG units directly attached to an inorganic core (R = (CH2CH2O)nOCH(3), 1-PEGn, n = 3, similar to 7, similar to 17, similar to 46), the absorption bands, associated with the low-energy transitions, continuously blue-shifted with the increasing PEG chain length. The chain length dependencies were also observed in the photoluminescence properties, particularly in the excitation spectral profiles. By combining the spectral features of several PEG17-modified clusters (2-C-m-PEG17 and 3) whose PEG and core units are separated by various alkyl chain-based spacers, it was demonstrated that sufficiently long PEG units, including PEG17 and PEG46, cause electronic perturbations in the cluster properties when they are arranged near the inorganic core. These unique effects of the long-PEG environments could be correlated with their large dipole moments, suggesting that the polarity of the proximal chemical environment is critical when affecting the electronic properties of the inorganic cluster core.
  • Mizuho Sugiuchi, Yukatsu Shichibu, Takayuki Nakanishi, Yasuchika Hasegawa, Katsuaki Konishi
    CHEMICAL COMMUNICATIONS 51 70 13519 - 13522 2015年 [査読有り][通常論文]
     
    An organometallic Au-13 cluster having two sigma-bonded acetylide ligands was synthesized and its structure was determined by X-ray crystallography. Absorption spectral studies indicated the presence of electronic coupling between the superatomic Au-13 core and the acetylide pi-orbitals, which was supported by theoretical considerations.

受賞

  • 2015年03月 日本化学会 学術賞
     
    受賞者: 小西 克明

共同研究・競争的資金等の研究課題

  • 金属クラスターと芳香族ユニットの間に働く引力相互作用の学理解明と機能開拓
    科学研究費補助金:基盤研究(B)
    研究期間 : 2018年04月 -2021年03月 
    代表者 : 小西 克明
  • 自己組織構造形成に駆動される二重ラセン型配位高分子の精密合成
    JSPS:科学研究費 挑戦的萌芽研究
    研究期間 : 2016年04月 -2017年03月 
    代表者 : 小西 克明
  • 有機小分子に誘発される発光性ナノ金属種の自己集合を利用した機能開拓
    JSPS:科学研究費 基盤研究(B)
    研究期間 : 2012年04月 -2015年03月 
    代表者 : 小西 克明
  • 無機クラスター高次ネットワーク構造の構築と機能創発
    文部科学省:科学研究費 新学術領域研究(計画)
    研究期間 : 2008年10月 -2013年03月 
    代表者 : 小西 克明
  • 有機・無機超分子複合体の設計と環境調和型システムへの応用
    科学研究費補助金
    研究期間 : 2004年 -2005年

教育活動情報

主要な担当授業

  • 環境物質科学基礎論Ⅲ
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 有機化学 Organic Chemistry
  • ナノ環境材料化学特論Ⅱ
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 有機高分子、無機高分子、クラスター、ナノ粒子、超分子 organic polymer, inorganic polymer synthesis, cluster, nanoparticle, supramolecules
  • 化学Ⅱ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 有機化合物、官能基、分子構造、化学的性質、化学反応、機能性有機物、生体関連有機物質

大学運営

学内役職歴

  • 2019年10月1日 - 2021年9月30日 大学院環境科学院副学院長
  • 2019年10月1日 - 2021年9月30日 大学院地球環境科学研究院副研究院長
  • 2019年4月1日 - 2019年9月30日 大学院環境科学院副学院長
  • 2019年4月1日 - 2019年9月30日 大学院地球環境科学研究院副研究院長


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