Updated on 2021/09/03

写真b

 
NIIHORI Yoshiki
 
*Items subject to periodic update by Rikkyo University (The rest are reprinted from information registered on researchmap.)
Affiliation*
College of Science Department of Chemistry
Title*
Assistant Professor
Degree
博士(理学) ( 東京理科大学 )
Contact information
Mail Address
Research Interests
  • Photochemistry

  • 物理化学

  • Campus Career*
    • 4 2017 - Present 
      College of Science   Department of Chemistry   Assistant Professor
     

    Research Areas

    • Nanotechnology/Materials / Fundamental physical chemistry

    Research History

    • 4 2017 - Present 
      RIKKYO UNIVERSITY   College of Science Department of Chemistry   Assistant Professor

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    • 4 2016 - 3 2017 
      Tokyo University of Science   Graduate School of chemical Science and Technology

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    • 4 2014 - 3 2016 
      Tokyo University of Science   Faculty of Science, Division 1 Applied Chemistry

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    Education

    • 4 2011 - 3 2014 
      Tokyo University of Science

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      Country: Japan

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    • 4 2009 - 3 2011 
      Tokyo University of Science

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      Country: Japan

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    • 4 2005 - 3 2009 
      Tokyo University of Science   Faculty of Science

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      Country: Japan

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    Committee Memberships

    • 4 2020 - 3 2022 
      ナノ学会   編集委員

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      Committee type:Academic society

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    Awards

    • 12 2020  
      Wiley  Angewandte Chemie International Edition (2021), Selected as "Hot Paper"  Single Platinum Atom Doping to Silver Clusters Enables Near‐Infrared‐to‐Blue Photon Upconversion
       
      Yoshiki Niihori, Yuki Wada, Masaaki Mitsui

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    • 12 2020  
      Wiley  Angewandte Chemie International Edition (2021), Selected as "Frontispiece"  Single Platinum Atom Doping to Silver Clusters Enables Near‐Infrared‐to‐Blue Photon Upconversion
       
      Yoshiki Niihori, Yuki Wada, Masaaki Mitsui

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    • 9 2019  
      分子科学会  第13回分子科学討論会 分子科学会優秀講演賞  発光解析に基づく配位子保護金属クラスターの平衡状態評価法の確立
       
      新堀佳紀

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      Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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    • 4 2019  
      American Chemical Society  J. Phys. Chem. C (2019) 誌 Supplementary Cover掲載 
       
      Yoshiki Niihori, Sayaka Hashimoto, Yuki Koyama, Sakiat Hossain, Wataru Kurashige, Yuichi Negishi

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      Award type:Other  Country:United States

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    • 4 2019  
      American Chemical Society  Journal of Physical Chemistry C, Selected as "Supplementary Cover"  Dynamic Behavior of Thiolate-Protected Gold–Silver 38-Atom Alloy Clusters in Solution
       
      Yoshiki Niihori, Sayaka Hashimoto, Yuki Koyama, Sakiat Hossain, Wataru Kurashige, Yuichi Negishi

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    • 8 2018  
      American Chemical Society  J. Phys. Chem. Lett. (2018) 誌 Supplementary Cover掲載  Atomic and Isomeric Separation of Thiolate-Protected Alloy Clusters
       
      Yoshiki Niihori, Yuki Koyama, Seiichiro Watanabe, Sayaka Hashimoto, Sakiat Hossain, Lakshmi V. Nair, Bharat Kumar, Wataru Kurashige, Yuichi Negishi

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      Award type:Honored in official journal of a scientific society, scientific journal  Country:United States

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    • 11 2017  
      Royal Society of Chemistry  Nanoscale (2018) 誌 Outside Back Cover掲載  High-performance Liquid Chromatography Mass Spectrometry of Gold and Alloy Clusters Protected by Hydrophilic Thiolates
       
      Yoshiki Niihori, Daisuke Shima, Kana Yoshida, Kota Hamada, Lakshmi V. Nair, Sakiat Hossain, Wataru Kurashige, Yuichi Negishi

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      Award type:Honored in official journal of a scientific society, scientific journal  Country:United Kingdom

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    • 5 2017  
      The Chemical Society of Japan  Chem. Rec. (2017) 誌 Outside Front Cover掲載  Understanding and Practical Use of Ligand and Metal Exchange Reactions in Thiolate-Protected Metal Clusters to Synthesize Controlled Metal Clusters
       
      Yoshiki Niihori, Sakiat Hossain, Sachil Sharma, Bharat Kumar, Wataru Kurashige, Yuichi Negishi

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      Award type:Honored in official journal of a scientific society, scientific journal  Country:Japan

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    • 1 2017  
      American Chemical Society  Ind. Eng. Chem. Res. (2017) 誌 Outside Front Cover掲載  Separation of Glutathionate-Protected Gold Clusters by Reversed-Phase Ion Pair High-Performance Liquid Chromatography
       
      Yoshiki Niihori, Yoshihiro Kikuchi, Daisuke Shima, Chihiro Uchida, Sachil Sharma, Sakiat Hossain, Wataru Kurashige, Yuichi Negishi

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      Award type:Honored in official journal of a scientific society, scientific journal  Country:United States

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    • 12 2015  
      日本MRS  第25回日本MRS奨励賞  配位子交換されたクラスターの位置異性体の高分解能分離と配位子交換反応メカニズムの解明
       
      新堀佳紀

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      Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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    • 8 2015  
      Royal Society of Chemistry  Phys. Chem. Chem. Phys. (2015) 誌 Outside Front Cover掲載 
       
      Yoshiki Niihori, Chihiro Uchida, Wataru Kurashige, Yuichi Negishi

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      Award type:Honored in official journal of a scientific society, scientific journal  Country:United Kingdom

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    • 3 2015  
      日本化学会  日本化学会第 95 春季年会(2015)優秀講演賞(学術)  高分解能高速液体クロマトグラフィーを駆使したチオ ラート保護金属クラスターにおける配位子交換反応のメカニ ズムの解明
       
      新堀佳紀

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      Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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    • 5 2014  
      ナノ学会  ナノ学会第12回大会若手優秀ポスター発表賞  二成分チオラート保護金属クラスターの精密分離 ー高分解能化へのキーファクターの解明ー
       
      新堀佳紀

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      Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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    • 4 2014  
      Royal Society of Chemistry  Nanoscale (2014) 誌 Outside Back Cover掲載  Advanced Use of High-Performance Liquid Chromatography for Synthesis of Controlled Metal Clusters
       
      Yoshiki Niihori, Miku Matsuzaki, Chihiro Uchida, Yuichi Negishi

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      Award type:Honored in official journal of a scientific society, scientific journal  Country:United Kingdom

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    • 4 2014  
      日本化学会  日本化学会第 94 春季年会(2014)学生講演賞  高速液体クロマトグラフィーを駆使した二成分チオラ ート保護金属クラスターの精密合成
       
      新堀佳紀

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      Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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    • 9 2013  
      分子科学会  第7回分子科学討論会(京都)2013 分子科学会優秀ポスター賞  配位子交換と逆相カラムの駆使による二種類のチオラートにより保護された金属クラスターの精密かつ系統的な合成法の確立
       
      新堀佳紀

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      Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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    • 10 2012  
      Royal Society of Chemistry  Nanoscale (2013) 誌 Outside Back Cover掲載  Remarkable Enhancement in Ligand-Exchange Reactivity of Thiolate-Protected Au25 Nanocluster by Single Pd Atom Doping
       
      Yoshiki Niihori, Wataru Kurashige, Miku Matsuzaki, Yuichi Negishi

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      Award type:Honored in official journal of a scientific society, scientific journal  Country:United Kingdom

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    Papers

    • Excited-State Symmetry Breaking in a Multiple Multipolar Chromophore Probed by Single-Molecule Fluorescence Imaging and Spectroscopy

      Masaaki Mitsui, Yasushi Takakura, Kazuya Hirata, Yoshiki Niihori, Yutaka Fujiwara, Kenji Kobayashi

      The Journal of Physical Chemistry B   29 8 2021

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      Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society (ACS)  

      DOI: 10.1021/acs.jpcb.1c04915

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    • Starburst-Shaped D−π–A Chromophores Possessing a Hexaethynylbenzene Core for Dye-Sensitized Solar Cells

      Masaaki Mitsui, Yushiro Nakagome, Yoshiki Niihori, Shota Inoue, Yutaka Fujiwara, Kenji Kobayashi

      ACS Applied Materials & Interfaces13 ( 30 ) 35739 - 35749   4 8 2021

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      Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society (ACS)  

      DOI: 10.1021/acsami.1c08431

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    • Single Platinum Atom Doping to Silver Clusters Enables Near‐Infrared‐to‐Blue Photon Upconversion

      Yoshiki Niihori, Yuki Wada, Masaaki Mitsui

      Angewandte Chemie International Edition60 ( 6 ) 2822 - 2827   8 2 2021

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      Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Wiley  

      DOI: 10.1002/anie.202013725

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      Other Link: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.202013725

    • Synthesis and Properties of a Cyclohexa‐2,7‐anthrylene Ethynylene Derivative

      Hironori Matsuki, Keisuke Okubo, Yuta Takaki, Yoshiki Niihori, Masaaki Mitsui, Eiichi Kayahara, Shigeru Yamago, Kenji Kobayashi

      Angewandte Chemie International Edition60 ( 2 ) 998 - 1003   11 1 2021

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      Publishing type:Research paper (scientific journal)   Publisher:Wiley  

      DOI: 10.1002/anie.202012120

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      Other Link: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.202012120

    • Photophysical and Thermodynamic Properties of Ag29(BDT)12(TPP)x (x = 0−4) Clusters in Secondary Ligand Binding-Dissociation Equilibria Unraveled by Photoluminescence Analysis Peer-reviewed

      Yoshiki Niihori, Naoya Takahashi, Masaaki Mitsui

      Journal of Physical Chemistry C124 ( 10 ) 5880 - 5886   16 2 2020

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

      Despite the huge effort that has been devoted to the atomically-precise synthesis and structural and physicochemical property characterization of ligand-protected noble metal clusters, quantitative knowledge of the thermodynamic equilibrium in solutions of these clusters to date remains lacking. In this paper, we report the determination of equilibrium constants for reversible binding-dissociation reactions of a secondary ligand, triphenylphosphine (TPP) in Ag29(BDT)12(TPP)x (x = 0−4) clusters (BDT: 1,3-benzenedithiolate), achieved through photoluminescence (PL) analysis. Detailed analyses of TPP-concentration dependencies of PL decay times and PL quantum yields of the clusters under equilibrium allowed us to extract the PL lifetimes (τx) and PL quantum yields (Φx) of each composition (x = 0−4). Using these PL parameters, we reveal in this study how the relative abundances of each composition vary with the TPP concentration. From the simulation of these dependencies, we obtained the stability and equilibrium constants for each binding-dissociation reaction step in the sequential equilibrium. More importantly, the parent clusters, Ag29(BDT)12(TPP)4, in the solution underwent sequential loss of TPP ligands and became the binding-dissociation equilibria due to modest magnitudes of the equilibrium constant (K = 102−104 M−1). Hence, our PL analysis approach is highly effective in determining the photophysical and thermodynamic parameters of inseparable clusters in dynamic equilibrium.

      DOI: 10.1021/acs.jpcc.9b11928

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    • Excited-State Symmetry Breaking of a Symmetrical Donor−π–Donor Quadrupolar Molecule at a Polymer/Glass Interface Peer-reviewed

      Masaaki Mitsui, Yasushi Takakura, Yoshiki Niihori, Masashi Nakamoto, Yutaka Fujiwara, Kenji Kobayashi

      Journal of Physical Chemistry C123 ( 21 ) 14564 - 14572   25 5 2019

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

      Symmetric multipolar (e.g., quadrupolar and octupolar) chromophores that undergo excited-state symmetry breaking in polar solvents have been drawing considerable attention for a long time as promising two-photon absorption and luminescent materials. However, this process has been generally restricted to liquid media. Herein, we report the excited-state symmetry breaking of a centrosymmetric D−π–D (donor−π–donor) quadrupolar molecule, DB2, occurring at a polymer/glass interface. In polar liquids, DB2 exhibits pronounced emission solvatochromism originating from symmetry-breaking intramolecular charge transfer in the S1 state. Single-molecule fluorescence spectroscopy shows that the fluorescence characteristics of DB2 at the interface are strikingly different from those of DB2 embedded in a polymer film, that is, the dramatic lengthening of fluorescence lifetimes and pronounced sharpening of fluorescence spectra are observed. With the aid of theoretical calculations, it is revealed that these characteristic behaviors are due to the strong electronic localization of the emitting excited state via asymmetric in-plane relaxation of the π-conjugated framework through dipolar interactions with the glass surface.

      DOI: 10.1021/acs.jpcc.9b03612

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    • Dynamic Behavior of Thiolate-Protected Gold–Silver 38-Atom Alloy Clusters in Solution Peer-reviewed

      Yoshiki Niihori, Sayaka Hashimoto, Yuki Koyama, Sakiat Hossain, Wataru Kurashige, Yuichi Negishi

      Journal of Physical Chemistry C123 ( 21 ) 13324 - 13329   11 4 2019

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

      This study examined the dynamic behavior of butanethiolate (SC4H9)-protected gold–silver 38-atom alloy clusters ([Au38–xAgx(SC4H9)24]0) in solution using reversed-phase high-performance liquid chromatography and electrospray ionization mass spectrometry. The results revealed that [Au38–xAgx(SC4H9)24]0 synthesized by reacting [Au38(SC4H9)24]0 with an Ag(I)–SC4H9 complex, which is the most frequently used method to synthesize gold–silver alloy clusters, continue to undergo intercluster metal exchange even after the distribution of the chemical composition of the clusters looks unchanged in the mass spectrum. The frequency of this intercluster metal exchange in solution varied depending on the standing time in solution and the synthesis method of [Au38–xAgx(SC4H9)24]0. These findings should be taken into consideration in future studies to realize deeper understanding of the physical and chemical properties of thiolate-protected gold–silver alloy clusters in solution.

      DOI: 10.1021/acs.jpcc.9b02644

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    • Deepening the Understanding of Thiolate-Protected Metal Clusters Using High-Performance Liquid Chromatography Peer-reviewed

      Yoshiki Niihori, Kana Yoshida, Sakiat Hossain, Wataru Kurashige, Yuichi Negishi

      Bulletin of the Chemical Society of Japan92 ( 3 ) 664 - 695   22 12 2018

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:CSJ Journal  

      DOI: 10.1246/bcsj.20180357

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    • Alloy Clusters: Precise Synthesis and Mixing Effects Invited Peer-reviewed

      Sakiat Hossain, Yoshiki Niihori, Lakshmi V. Nair, Bharat Kumar, Wataru Kurashige, Yuichi Negishi

      Accounts of Chemical Research51 ( 21 ) 3114 - 3124   21 11 2018

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

      DOI: 10.1021/acs.accounts.8b00453

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    • Impacts of Environmental Rigidity on Photophysical Characteristics and Behaviors of a Quadrupolar Chromophore Revealed by Single-Molecule Fluorescence Spectroscopic Study Peer-reviewed

      Toshinari Mizukami, Shota Inoue, Hirokazu Ohsawa, Yoshiki Niihori, Kenji Kobayashi, Masaaki Mitsui

      Journal of Physical Chemistry C122 ( 37 ) 21295 - 21307   3 9 2018

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

      Multipolar chromophores (e.g., quadrupolar and octupolar molecules) have excellent two-photon absorption properties and exhibit characteristic excited-state relaxation behaviors that involve structural symmetry breaking. Environmental rigidity could provide an appreciable impact on such conformational rearrangement in the excited state; however, details of its effect remain unclear. Herein, we undertake an ensemble and single-molecule spectroscopic investigation into the effects of environmental rigidity on the photophysical characteristics and behaviors of a newly synthesized D−π–A−π–D (donor−π–acceptor−π–donor) quadrupolar chromophore, QC, and its π–A−π analogue, AC, in various solutions and polymers. The fluorescence emission of QC in nonpolar solvents takes place in the symmetric quadrupolar state [Dδ+–π–Aδ−–π–Dδ+]*, whereas the significant fluorescence quenching is observed with increasing solvent polarity, suggesting the gradual stabilization of the nonemissive symmetry-broken dipolar state [Dδ+–π–Aδ−]*−π–D or D−π–[Aδ−–π–Dδ+]* in more polar solvents. However, because of a lack of environmental rearrangement, this dipolar state is not effectively stabilized in a polar polymer matrix. Single-molecule fluorescence spectroscopy was used to explore how environmental rigidity affects the photophysical behaviors of QC and AC. In a rubbery poly(methyl acrylate) (PMA) film, the QC and AC single molecules exhibited fluorescence properties similar to those in nonpolar solutions. Remarkably, the average fluorescence lifetime of QC in the glassy PMA film was longer than that in the rubbery film. Moreover, the heterogeneity of single-molecule fluorescence lifetimes increased considerably, although such variation was not observed for the nonquadrupolar chromophore AC. Experimental and theoretical considerations suggest that fluorescence emission of QC embedded in the rubbery polymer most probably occurs from the symmetric quadrupolar state formed through planarization, whereas such conformational relaxation is suppressed in the glassy polymer because the physical constraint and various degree-of-twist conformations of QC emit fluorescence photons. Overall, this study reveals that environmental rigidity appreciably alters the photophysical characteristics and behaviors of quadrupolar chromophores.

      DOI: 10.1021/acs.jpcc.8b03889

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    • Atomic and Isomeric Separation of Thiolate-Protected Alloy Clusters Peer-reviewed

      Yoshiki Niihori, Yuki Koyama, Seiichiro Watanabe, Sayaka Hashimoto, Sakiat Hossain, Lakshmi V. Nair, Bharat Kumar, Wataru Kurashige, Yuichi Negishi

      Journal of Physical Chemistry Letter9 ( 17 ) 4930 - 4934   1 8 2018

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

      Techniques to control the chemical compositions and geometric structures of alloy clusters are indispensable to understand the correlation between the structures and physical/chemical properties of alloy clusters. In this study, we established a method to separate thiolate-protected 25-atom gold–silver alloy clusters (Au25–xAgx(SR)18) according to their chemical composition and structural isomer. Furthermore, using this method, we revealed that an isomeric distribution of the products exists in Au25–xAgx(SR)18 (x ≥ 2) and that the distribution of these isomers depends on the synthesis method and standing time in solution. In this study, it was also demonstrated that the continuous discretization of the electronic structure is induced by the Ag substitution. This method can also be used to separate mixtures of [Au24M(SR)18]0 (M = Au, Pt, or Pd) and other Au–Ag alloy clusters ([Au36–xAgx(SR)24]0 and [Au38–xAgx(SR)24]0). This method is expected to be used to obtain comprehensive knowledge of the structural–property correlation of alloy clusters.

      DOI: 10.1021/acs.jpclett.8b02211

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    • Au25-Loaded BaLa4Ti4O15 Water-Splitting Photocatalyst with Enhanced Activity and Durability Produced Using New Chromium Oxide Shell Formation Method Peer-reviewed

      Wataru Kurashige, Rina Kumazawa, Daiki Ishii, Rui Hayashi, Yoshiki Niihori, Sakiat Hossain, Lakshmi V. Nair, Tomoaki Takayama, Akihide Iwase, Seiji Yamazoe, Tatsuya Tsukuda, Akihiko Kudo, Yuichi Negishi

      The Journal of Physical Chemistry C122 ( 25 ) 13669 - 13681   28 6 2018

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society ({ACS})  

      We report herein remarkable improvement of activity and stability of an Au25-loaded BaLa4Ti4O15 water-splitting photocatalyst. We first examined the influence of refining the gold cocatalyst on the individual reactions over the BaLa4Ti4O15 photocatalyst in this water-splitting system. The results revealed that refining the gold cocatalyst accelerates not only the hydrogen generation reaction, but also oxygen photoreduction reaction, which suppresses the H2 generation via photoreduction of protons. This finding suggests that photocatalytic activity will be enhanced if the O2 photoreduction reaction can be selectively suppressed by covering Au25 with a Cr2O3 shell which is impermeable to O2 but permeable to H+. Then, we developed new method for the formation of the Cr2O3 shell onto Au25. Our method utilizes the strong metal–support interaction between them. Water-splitting photoactivity of Au25–BaLa4Ti4O15 was improved by 19 times under an optimized coverage of the Cr2O3 shell. The Cr2O3 shell also elongated the lifetime of the photocatalysts by preventing the agglomeration of Au25 cocatalysts.

      DOI: 10.1021/acs.jpcc.8b00151

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    • Thiolate-Protected Trimetallic Au∼20Ag∼4Pd and Au∼20Ag∼4Pt Alloy Clusters with Controlled Chemical Composition and Metal Positions Peer-reviewed

      Sakiat Hossain, Tasuku Ono, Mahiro Yoshioka, Guoxiang Hu, Mai Hosoi, Zhaoheng Chen, Lakshmi V. Nair, Yoshiki Niihori, Wataru Kurashige, De-En Jiang, Yuichi Negishi

      Journal of Physical Chemistry Letters9 ( 10 ) 2590 - 2594   17 5 2018

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

      The mixing of heteroelements in metal clusters is a powerful approach to generate new physical/chemical properties and functions. However, as the kinds of elements increase, control of the chemical composition and geometric structure becomes difficult. We succeeded in the compositionally selective synthesis of phenylethanethiolate-protected trimetallic Au∼20Ag∼4Pd and Au∼20Ag∼4Pt clusters, Au∼20Ag∼4Pd(SC2H4Ph)18 and Au∼20Ag∼4Pt(SC2H4Ph)18. Single-crystal X-ray structural analysis revealed the precise position of each metal element in these metal clusters. Reacting with thiol at an elevated temperature was found to be important to direct the metal elements to the most stable positions. The electronic structures of these trimetallic clusters become more discretized than those of the related bimetallic clusters due to orbital splitting.

      DOI: 10.1021/acs.jpclett.8b00910

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    • High-performance liquid chromatography mass spectrometry of gold and alloy clusters protected by hydrophilic thiolates Peer-reviewed

      Yoshiki Niihori, Daisuke Shima, Kana Yoshida, Kota Hamada, Lakshmi V. Nair, Sakiat Hossain, Wataru Kurashige, Yuichi Negishi

      Nanoscale10 ( 4 ) 1641 - 1649   28 1 2018

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry  

      In this work, we found two hydrophilic interaction liquid chromatography (HILIC) columns for high-performance liquid chromatography (HPLC) suitable for the high-resolution separation of hydrophilic metal clusters. The mass distributions of the product mixtures of hydrophilic metal clusters were evaluated via HPLC mass spectrometry (LC/MS) using these HILIC columns. Consequently, we observed multiple clusters that had not been previously reported for glutathionate (SG)-protected gold clusters (Aun(SG)m). Additionally, we demonstrated that Aun-xMx(SG)m alloy clusters (M = Ag, Cu, or Pd) in which part of the Au in the Aun(SG)m cluster is replaced by a heteroelement can be synthesized, similar to the case of hydrophobic alloy clusters. It is easy to evaluate the mass distributions of hydrophilic metal clusters using this method. Thus, remarkable progress in the synthesis techniques of hydrophilic metal clusters through the use of this method is anticipated, as is the situation for hydrophobic metal clusters.

      DOI: 10.1039/c7nr07840d

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    • Perspective: Exchange reactions in thiolate-protected metal clusters Invited Peer-reviewed

      Yoshiki Niihori, Sakiat Hossain, Bharat Kumar, Lakshmi V. Nair, Wataru Kurashige, Yuichi Negishi

      APL MATERIALS5 ( 5 ) 053201   5 2017

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER INST PHYSICS  

      Thiolate-protected metal clusters can exchange ligands or metal atoms with other substances such as coexisting ligands, complexes, and metal clusters in solution. Using these reactions, it is possible to synthesize metal clusters with new physical and chemical properties. Although the occurrence of such reactions was recognized nearly 20 years ago, their details were not well understood. In recent years, techniques for the precise synthesis of metal clusters and their characterization have progressed considerably and, as a result, details of these reactions have been clarified. In this perspective, we focus on the most-studied thiolate-protected gold clusters and provide a summary of recent findings as well as future expectations concerning the exchange reactions of these clusters. (C) 2017 Author(s).

      DOI: 10.1063/1.4978373

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    • Understanding and Practical Use of Ligand and Metal Exchange Reactions in Thiolate-Protected Metal Clusters to Synthesize Controlled Metal Clusters Invited Peer-reviewed

      Yoshiki Niihori, Sakiat Hossain, Sachil Sharma, Bharat Kumar, Wataru Kurashige, Yuichi Negishi

      CHEMICAL RECORD17 ( 5 ) 473 - 484   5 2017

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

      It is now possible to accurately synthesize thiolate (SR)-protected gold clusters (Au-n (SR)(m)) with various chemical compositions with atomic precision. The geometric structure, electronic structure, physical properties, and functions of these clusters are well known. In contrast, the ligand or metal atom exchange reactions between these clusters and other substances have not been studied extensively until recently, even though these phenomena were observed during early studies. Understanding the mechanisms of these reactions could allow desired functional metal clusters to be produced via exchange reactions. Therefore, we have studied the exchange reactions between Au-n(SR)(m) and analogous clusters and other substances for the past four years. The results have enabled us to gain deep understanding of ligand exchange with respect to preferential exchange sites, acceleration means, effect on electronic structure, and intercluster exchange. We have also synthesized several new metal clusters using ligand and metal exchange reactions. In this account, we summarize our research on ligand and metal exchange reactions.

      DOI: 10.1002/tcr.201700002

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    • [Pt-17(CO)(12)(PPh3)(8)](n+) (n=1, 2): Synthesis and Geometric and Electronic Structures Invited Peer-reviewed

      Lakshmi V. Nair, Sakiat Hossain, Shota Wakayama, Shunjiro Takagi, Mahiro Yoshioka, Jun Maekawa, Atsuya Harasawa, Bharat Kumar, Yoshiki Niihori, Wataru Kurashige, Yuichi Negishi

      JOURNAL OF PHYSICAL CHEMISTRY C121 ( 20 ) 11002 - 11009   5 2017

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      Recently, platinum (Pt) clusters have attracted attention as miniaturized fuel cell redox catalysts. Although Pt clusters can be synthesized with atomic accuracy using carbon monoxide (CO) and phosphine as ligands, few studies have examined their electronic structure. We obtained experimental information about the electronic structure of these Pt clusters. We precisely synthesized the cationic Pt-17 cluster, [Pt-17(CO)(12)(PPh3)(8)](n+) (n = 1, 2), protected by CO and triphenylphosphine (PPh3) by a simple method and studied its geometric and electronic structures by single-crystal X-ray structure analysis, X-ray photoelectron spectroscopy, optical absorption spectroscopy, differential pulse voltammetry, and photoluminescence spectroscopy. The results indicated that cationic [Pt-17(CO)(12)(PPh3)(8)](n+) (n = 1, 2) has a geometric structure similar to that of previously reported neutral Pt-17(CO)(12)(PEt3)(8). The Pt-17 skeleton of Pt-17(CO)(12)(PPh3)(8) depended on the charge state of the cluster [Pt-17(CO)(12)(PPh3)(8)](+) or [Pt-17(CO)(12)(PPh3)(8)](2+)). [Pt-17(CO)(12)(PPh3)(8)](n+) (n = 1, 2) possessed a discretized electronic structure, similar to that of fine gold clusters, and exhibited photoluminescence in the near-infrared region. This research will aid fundamental and applied research on Pt clusters.

      DOI: 10.1021/acs.jpcc.7b00978

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    • Separation of Glutathionate-Protected Gold Clusters by Reversed-Phase Ion-Pair High-Performance Liquid Chromatography Invited Peer-reviewed

      Yoshiki Niihori, Yoshihiro Kikuchi, Daisuke Shima, Chihiro Uchida, Sachil Sharma, Sakiat Hossain, Wataru Kurashige, Yuichi Negishi

      INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH56 ( 4 ) 1029 - 1035   2 2017

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      Recent studies have demonstrated that reversed-phase high-performance liquid chromatography (RP-HPLC) is a very effective means of separating thiolate (SR)-protected gold clusters (Au-n(SR)(m)). In the present study, we applied RP-HPLC to the separation of hydrophilic glutathionate (SG)-protected Au-n(SG)(m) clusters. To achieve such separation, an ion pair reagent was dissolved in the solution to form ion pairs with the functional groups on the cluster surfaces, improving the interaction between the cluster surfaces and the hydrophobic stationary phase, representing ion pair chromatography. This technique resulted in the high-resolution separation of Au-n(SG)(m) clusters via RP-HPLC. Experiments at different solution pH values led to slight improvements in the resolution, showing that pH adjustment, which modifies the efficiency of the ion pair formation process, is a useful technique for improving this type of separation.

      DOI: 10.1021/acs.iecr.6b03814

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    • Ligand Exchange Reactions in Thiolate-Protected Au-25 Nanoclusters with Selenolates or Tellurolates: Preferential Exchange Sites and Effects on Electronic Structure Peer-reviewed

      Sakiat Hossain, Wataru Kurashige, Shota Wakayama, Bharat Kumar, Lakshmi V. Nair, Yoshiki Niihori, Yuichi Negishi

      JOURNAL OF PHYSICAL CHEMISTRY C120 ( 45 ) 25861 - 25869   11 2016

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      Ligand exchange reactions can introduce new ligands onto clusters to afford new physical/chemical properties and functions. Many studies on the ligand exchange reactions of thiolate-protected gold clusters using other chalcogenates (i.e., selenolates or tellurolates) as exchange ligands have been conducted in recent years. However, there is limited information on the preferential exchange sites and electronic structure of the exchanged products. In this study, we investigated the geometric and electronic structures of the products obtained by reacting [Au-25(SC2H4Ph)(18)] with PhSeH or (PhTe)(2) by single-crystal X-ray structural analysis, differential pulse voltammetry, and optical absorption spectroscopy. The results revealed that these exchange reactions preferentially produce products containing substituted ligands close to the gold core. In addition, we quantitatively determined the changes in the redox potentials and optical transition energies induced by continuous ligand exchange. This systematic investigation revealed that exchange with SePh induces nonlinear changes in the electronic structure of the clusters with the number of exchanged ligands. These findings are expected to lead to the improved design guidelines to produce clusters with new functions by ligand exchange with other chalcogenates.

      DOI: 10.1021/acs.jpcc.6b08636

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    • Precise synthesis, functionalization and application of thiolate-protected gold clusters Invited Peer-reviewed

      Wataru Kurashige, Yoshiki Niihori, Sachil Sharma, Yuichi Negishi

      COORDINATION CHEMISTRY REVIEWS320   238 - 250   8 2016

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE SA  

      Thiolate-protected gold clusters (Au-n(SR)(m)) have received significant attention as new functional nano materials because they exhibit size-specific physical and chemical properties that are not seen in bulk gold. To date, our research group has studied the following three aspects of Au-n(SR)(m) and related clusters: (1) the development of new methods allowing precise synthesis; (2) the establishment of new methods to impart high functionality; and (3) the utilization of these clusters as active sites in photocatalytic materials. This review summarizes our most recent work concerning these three subjects. (C) 2016 Elsevier B.V. All rights reserved.

      DOI: 10.1016/j.ccr.2016.02.013

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    • Improvements in the Ligand-Exchange Reactivity of Phenylethanethiolate-Protected Au-25 Nanocluster by Ag or Cu Incorporation Peer-reviewed

      Yoshiki Niihori, Makoto Eguro, Ayano Kato, Sachil Sharma, Bharat Kumar, Wataru Kurashige, Katsuyuki Nobusada, Yuichi Negishi

      JOURNAL OF PHYSICAL CHEMISTRY C120 ( 26 ) 14301 - 14309   7 2016

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      This study reports improvements in the ligand-exchange reactivity of phenylethanethiolate-protected Au-25 cluster (Au-25(SC2H4Ph)(18)) following Ag or Cu incorporation. Following the synthesis of Au25-xMx(SC2H4Ph)(18) (M = Au, Ag, Cu, or Pd), we determined the ligand-exchange reaction rates, using octanethiol (C8H17SH) as the exchange ligand, by employing mass spectrometry. The results show that incorporating Ag and Cu enhances the ligand-exchange reactivity of the clusters. On the basis of density functional theory calculations, it is concluded that the elevated reactivity of Au25-xMx(SC2H4Ph)(18) (M = Ag or Cu) results from the more highly positive charge density of metal atoms in the staple upon Ag or Cu substitution. In addition, in the presence of Au25-xMx(SC2H4Ph)(18) (M = Ag or Cu; x not equal 0), an improvement in the ligand-exchange reaction rate was also observed for Au-25(SC2H4Ph)(18), even though this cluster does not include a heteroatom. This unexpected behavior is attributed to the contribution of a chemical reaction between clusters. These findings are expected to deepen our understanding of ligand-exchange reactions, and lead to design guidelines for the creation of Au-n(SR)(m) clusters exhibiting new chemical compositions and functions, using this reaction.

      DOI: 10.1021/acs.jpcc.6b03812

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    • High-resolution separation of thiolate-protected gold clusters by reversed-phase high-performance liquid chromatography Invited Peer-reviewed

      Yoshiki Niihori, Chihiro Uchida, Wataru Kurashige, Yuichi Negishi

      PHYSICAL CHEMISTRY CHEMICAL PHYSICS18 ( 6 ) 4251 - 4265   2 2016

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

      Thiolate (RS)-protected gold clusters (Au-n(SR)(m)) have attracted much attention as building blocks of functional nanomaterials. Our group has been studying the high-resolution separation of Au-n(SR)(m) clusters using reversed-phase high-performance liquid chromatography. In this perspective, we summarize our recent results on the separation of Au-n(SR)(m) clusters and their doped clusters according to the core size, charge state, ligand composition, and coordination isomers. Additionally, this perspective describes new findings obtained by using high-resolution separation and future prospects for the separation of such types of metal clusters. We believe that the techniques and knowledge gained in this study would contribute to the creation of Au-n(SR)(m) clusters with the desired functions and associated functional nanomaterials.

      DOI: 10.1039/c5cp04660b

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    • Tuning the electronic structure of thiolate-protected 25-atom clusters by co-substitution with metals having different preferential sites Peer-reviewed

      Sachil Sharma, Seiji Yamazoe, Tasuku Ono, Wataru Kurashige, Yoshiki Niihori, Katsuyuki Nobusada, Tatsuya Tsukuda, Yuichi Negishi

      DALTON TRANSACTIONS45 ( 45 ) 18064 - 18068   2016

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

      Trimetallic Au24-xAgxPd and tetrametallic Au24-x-yAgxCuyPd clusters were synthesized by the subsequential metal exchange reactions of dodecanethiolate-protected Au24Pd clusters. EXAFS measurements revealed that Pd, Ag, and Cu dopants preferentially occupy the center and edge sites of the core, and staple sites, respectively. Spectroscopic and theoretical studies demonstrated that the synergistic effects of multiple substitutions on the electronic structures are additive in nature.

      DOI: 10.1039/c6dt03214a

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    • Understanding Ligand-Exchange Reactions on Thiolate-Protected Gold Clusters by Probing Isomer Distributions Using Reversed-Phase High-Performance Liquid Chromatography Peer-reviewed

      Yoshiki Niihori, Yoshihiro Kikuchi, Ayano Kato, Miku Matsuzaki, Yuichi Negishi

      ACS NANO9 ( 9 ) 9347 - 9356   9 2015

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      Thiolate-protected gold clusters (Au-n(SR)(m)) have attracted considerable attention as functional nanomaterials in a wide range of fields. A ligand-exchange reaction has long been used to functionalize these clusters. In this study, we separated products from a ligand-exchange reaction of phenylethanethiolate-protected Au24Pd clusters (Au24Pd(SC2H4Ph)(18)), in which Au-25(SR)(18) is doped with palladium, into each coordination isomer with high resolution by reversed-phase high-performance liquid chromatography. This success has enabled isomer distributions of the products to be quantitatively evaluated. We evaluated quantitatively the isomer distributions of products obtained by the reaction of Au24Pd(SC2H4Ph)(18) with thiol, disulfide, or diselenide. The results revealed that the exchange reaction starts to occur preferentially at thiolates that are bound directly to the metal core (thiolates of a core site) in all reactions. Further study on the isomer-separated Au24Pd(SC2H4Ph)(17)(SC12H25) revealed that clusters vary the coordination isomer distribution in solution by the ligand-exchange reaction between clusters and that control of the coordination isomer distribution of the starting clusters enables control of the coordination isomer distribution of the products generated by ligand-exchange reactions between clusters. Au24Pd(SC2H4Ph)(18) used in this study has a similar framework structure to Au-25(SR)(18), which is one of the most studied compounds in the Au-n(SR)(m) clusters. Knowledge gained in this study is expected to enable further understanding of ligand-exchange reactions on Au-25(SR)(18) and other Au-n(SR)(m) clusters.

      DOI: 10.1021/acsnano.5b03435

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    • Controlled Loading of Small Au-n Clusters (n=10-39) onto BaLa4Ti4O15 Photocatalysts: Toward an Understanding of Size Effect of Cocatalyst on Water-Splitting Photocatalytic Activity Peer-reviewed

      Yuichi Negishi, Yoshiki Matsuura, Ryota Tomizawa, Wataru Kurashige, Yoshiki Niihori, Tomoaki Takayama, Akihide Iwase, Akihiko Kudo

      JOURNAL OF PHYSICAL CHEMISTRY C119 ( 20 ) 11224 - 11232   5 2015

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      We have recently succeeded in loading extremely small monodisperse gold clusters (1.2 +/- 0.3 nm) as cocatalysts on a water-Splitting BaLa4Ti4O15 photocatalyst using a glutathione-protected Au-25 cluster (Au-25(SG)(18)) as a precursor; an improved photo catalytic activity of 2.6-fold was obtained when compared with that of BaLa4Ti4O15 onto which large gold nanoparticles (10-30 nm) were loaded. In the current study, the controlled loading of a series of ultrasmall Au-n clusters onto BaLa4Ti4O15 using various Au-n(SG)(m) clusters (n = 10, 15, 18, 22, 25, 29, 33, 39) was examined. The results revealed that the use of a highly stable cluster as a precursor is essential fat achieving control over the loading of the gold clusters. Additionally, the origin of the improved photocatalytic activity owing to the ultra miniaturization of the cocatalyst was reconsidered herein based on the photocatalytic activities of the obtained photocatalysts. The results strongly suggested that the activity per gold atom on the surface decreased significantly owing to the ultra miniaturization of the cocatalyst and that the origin of the improved activity is the increase in the number of surface gold atoms at a rate that overcomes the reduction effect in their activity.

      DOI: 10.1021/jp5122432

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    • A Critical Size for Emergence of Nonbulk Electronic and Geometric Structures in Dodecanethiolate-Protected Au Clusters Peer-reviewed

      Yuichi Negishi, Tafu Nakazaki, Sami Maloa, Shinjiro Takano, Yoshiki Niihori, Wataru Kurashige, Seiji Yamazoe, Tatsuya Tsukuda, Hannu Hakkinen

      JOURNAL OF THE AMERICAN CHEMICAL SOCIETY137 ( 3 ) 1206 - 1212   1 2015

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      We report on how the transition from the bulk structure to the cluster-specific structure occurs in n-dodecanethiolate-protected gold clusters, Aun(SC12)(m). To elucidate this transition, we isolated a series of Aun(SC12)(m) in the n range from 38 to similar to 520, containing five newly identified or newly isolated clusters, Au-104(SC12)(45), Au-similar to 226(SC12)(similar to 76), Au-similar to 253(SC12)(similar to 90), Au-similar to 356(SC12()similar to 112), and Au-similar to 520(SC12)(similar to 130), using reverse-phase high-performance liquid chromatography. Low-temperature optical absorption spectroscopy, powder X-ray diffractometry, and density functional theory (DFT) calculations revealed that the Au cores of Au-144(SC12)(60) and smaller clusters have molecular-like electronic structures and non-fcc geometric structures, whereas the structures of the Au cores of larger clusters resemble those of the bulk gold. A new structure model is proposed for Au-104(SC12)(45) based on combined approach between experiments and DFT calculations.

      DOI: 10.1021/ja5109968

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    • Recent Progress in the Functionalization Methods of Thiolate-Protected Gold Clusters Invited Peer-reviewed

      Wataru Kurashige, Yoshiki Niihori, Sachil Sharma, Yuichi Negishi

      JOURNAL OF PHYSICAL CHEMISTRY LETTERS5 ( 23 ) 4134 - 4142   12 2014

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      Nanomaterials that exhibit both stability and functionality are currently considered to hold great promise as components of nanotechnology devices. Thiolate-protected gold clusters (Au-n(SR)(m)) have long attracted attention as functional nanomaterials. Magic Au-n(SR)(m) dusters are an especially stable group of thiolate-protected clusters that have particularly high potential as functional materials. Although numerous application experiments have been conducted for magic Au-n(SR)(m) clusters, it is important that functionalization methods are also established to allow for effective utilization of these materials. The results of recent research on heteroatom doping and the use of other chalcogenide ligands strongly suggest that these strategies are promising as functionalization methods of magic Au-n(SR)(m) clusters. In this Perspective, we focus on studies relating to three representative types of magic clusters-Au-25(SR)(18), Au-38(SR)(24), and Au-144(SR)(60)-and discuss the recent progress and future issues.

      DOI: 10.1021/jz501941p

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    • 金属クラスターに対する高次の精密合成技術の確立

      新堀佳紀

          20 3 2014

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      Language:Japanese   Publishing type:Doctoral thesis  

      DOI: 10.20604/00000010

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    • Advanced use of high-performance liquid chromatography for synthesis of controlled metal clusters

      Yoshiki Niihori, Miku Matsuzaki, Chihiro Uchidaa, Yuichi Negishi

      NANOSCALE6 ( 14 ) 7889 - 7896   2014

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

      Because the synthesis of metal clusters with multiple ligand types results in a distribution of ligands, high-resolution separation of each unique cluster from the mixture is required for precise control of the ligand composition. Reverse-phase high-performance liquid chromatography combined with appropriate transitioning of the mobile phase composition is an extremely effective means of separating ligand combinations when working with metal clusters protected by two different types of thiolates. We report herein advanced use of this method. The studies involving Au24Pd(SR1)(18-x)(SR2)(x) and Au24Pd(SR1)(18-x)(SeR2)(x) (SR1, SR2 = thiolate, SeR2 = selenolate) revealed the following. (1) In general, an increase in the difference between the polarities of the functional groups incorporated in the two types of ligands improves the separation resolution. A suitable ligand combination for separation can be predicted from the retention times of Au24Pd(SR1)(18) and Au24Pd(SR2)(18), which cause the terminal peaks in a series of peaks. (2) The use of a step-gradient program during the mobile phase substitution results in improved resolution compared to that achievable with the linear gradients applied in prior work. (3) This technique is also useful for the evaluation of the chemical compositions of metal clusters protected by two different types of ligands with similar molecular weights. These findings will provide clear design guidelines for the functionalization of metal clusters via control of the ligand composition, and will also improve our understanding of the high-resolution isolation of metal clusters.

      DOI: 10.1039/c4nr01144a

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    • Toward the creation of stable, functionalized metal clusters Invited Peer-reviewed

      Yuichi Negishi, Wataru Kurashige, Yoshiki Niihori, Katsuyuki Nobusada

      Physical Chemistry Chemical Physics15 ( 43 ) 18736 - 18751   21 11 2013

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry  

      Nanomaterials which exhibit both stability and functionality are currently considered to hold the most promise as components of nanotechnology devices. Thiolate (RS)-protected gold nanoclusters (Aun(SR)m) have attracted significant attention in this regard and, among these, the magic clusters are believed to be the best candidates since they are the most stable. We have investigated the effects of heteroatom doping, protection by selenolate ligands and protection by photoresponsive thiolates on the stability and physical/chemical properties of these clusters. Through such studies, we have attempted to establish methods of modifying magic Aun(SR)m clusters as a means of creating metal clusters that are both robust and functional. This paper summarizes our studies towards this goal and the obtained results. © 2013 the Owner Societies.

      DOI: 10.1039/c3cp52837e

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    • Separation of Precise Compositions of Noble Metal Clusters Protected with Mixed Ligands Peer-reviewed

      Yoshiki Niihori, Miku Matsuzaki, Thalappil Pradeep, Yuichi Negishi

      JOURNAL OF THE AMERICAN CHEMICAL SOCIETY135 ( 13 ) 4946 - 4949   4 2013

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

      This report describes the precise and systematic synthesis of PdAu24 clusters protected with two types of thiolate ligands (-SR1 and -SR2). It involved high-resolution separation of metal clusters containing a distribution of chemical compositions, PdAu24(SR1)(18-n) (SR2)(n) (n = 0, 1, 2,..., 18), to individual clusters of specific n using high-performance liquid chromatography. Similar high-resolution separation was achieved for a few ligand combinations as well as clusters with other metal cores, such as Au-25 and Au-38. These results demonstrate the ability to precisely control the chemical composition of two types of ligands in thiolate-protected mono- and bimetallic metal clusters. It is expected that greater functional control of thiolate-protected metal clusters, their regular arrays, and systematic variation of their properties can now be achieved.

      DOI: 10.1021/ja4009369

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    • Remarkable enhancement in ligand-exchange reactivity of thiolate-protected Au-25 nanoclusters by single Pd atom doping Peer-reviewed

      Yoshiki Niihori, Wataru Kurashige, Miku Matsuzaki, Yuichi Negishi

      NANOSCALE5 ( 2 ) 508 - 512   2013

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

      The effect of Pd doping on the ligand-exchange reactivity of Au-25(SC12H25)(18) was studied by comparing the ligand-exchange reactivity of [Au-25(SC12H25)(18)](-) and [PdAu24(SC12H25)(18)](0) and the results clearly demonstrate that, regardless of the kind of incoming thiols and solvents, Pd doping greatly increases the rate of ligand exchange of Au-25(SC12H25)(18), indicating an enhanced ease of ligand exchange.

      DOI: 10.1039/c2nr32948d

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    • Isolation and structural characterization of magic silver clusters protected by 4-(tert-butyl)benzyl mercaptan Peer-reviewed

      Yuichi Negishi, Rio Arai, Yoshiki Niihori, Tatsuya Tsukuda

      CHEMICAL COMMUNICATIONS47 ( 20 ) 5693 - 5695   2011

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

      Small silver clusters (average diameter of 1.2 nm) protected by 4-(tert-butyl)benzyl mercaptan (BBSH) were converted to stable, monodisperse clusters (2.1 nm) by a ripening process with excess amount of BBSH. Multiple characterizations of the isolated magic clusters revealed an approximate chemical composition of Ag(similar to 280)(SBB)(similar to 120).

      DOI: 10.1039/c0cc05587e

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    • Isolation, structure, and stability of a dodecanethiolate-protected Pd1Au24 cluster Peer-reviewed

      Yuichi Negishi, Wataru Kurashige, Yoshiki Niihori, Takeshi Iwasa, Katsuyuki Nobusada

      PHYSICAL CHEMISTRY CHEMICAL PHYSICS12 ( 23 ) 6219 - 6225   2010

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

      A dodecanethiolate-protected Pd1Au24(SC12H25)(18) cluster, which is a mono-Pd-doped cluster of the well understood magic gold cluster Au-25(SR)(18), was isolated in high purity using solvent fractionation and high-performance liquid chromatography (HPLC) after the preparation of dodecanethiolate-protected palladium-gold bimetal clusters. The cluster thus isolated was identified as the neutral [Pd1Au24(SC12H25)(18)](0) from the retention time in reverse phase columns and by elemental analyses. The LDI mass spectrum of [Pd1Au24(SC12H25)(18)](0) indicates that [Pd1Au24(SC12H25)(18)](0) adopts a similar framework structure to Au-25(SR)(18), in which an icosahedral Au-13 core is protected by six [-S-Au-S-Au-S-] oligomers. The optical absorption spectrum of [Pd1Au24(SC12H25)(18)](0) exhibits peaks at similar to 690 and similar to 620 nm, which is consistent with calculated results on [Pd-1@Au-24(SC1H3)(18)](0) in which the central gold atom of Au-25(SC1H3)(18) is replaced with Pd. These results strongly indicate that the isolated [Pd1Au24(SC12H25)(18)](0) has a core-shell [Pd-1@Au-24(SC12H25)(18)](0) structure in which the central Pd atom is surrounded by a frame of Au-24(SC12H25)(18). Experiments on the stability of the cluster showed that Pd-1@Au-24(SC12H25)(18) is more stable against degradation in solution and laser dissociation than Au-25(SC12H25)(18). These results indicate that the doping of a central atom is a powerful method to increase the stability beyond the Au-25(SR)(18) cluster.

      DOI: 10.1039/b927175a

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    Misc.

    • チオラート保護貴金属クラスターの光物理:その理解の現状と応用 Invited

      新堀佳紀, 三井正明

      光化学52 ( 2 ) 67 - 74   8 2021

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      Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

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    • 配位子保護金属クラスターを用いた近赤外-可視光変換

      新堀佳紀

      Chem-Station, スポットライトリサーチ   6 2021

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      Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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    • 意外と柔らかい?ナノの世界の小さな金属

      新堀佳紀

      月刊化学75 ( 1 ) 65 - 66   12 2019

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      Authorship:Lead author   Publishing type:Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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    • HPLCによるチオラート保護金属クラスターの基本的性質の解明 Invited Peer-reviewed

      根岸雄一, 橋本彩加, 海老名彩乃, 浜田幸太, 若松光祐, 新堀佳紀

      分析化学68 ( 11 ) 825 - 838   8 2019

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      Authorship:Last author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

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    • 逆相高速液体クロマトグラフィーによるフェニルエタンチオラート保護金銀38原子合金クラスターの原子精度での精密分離 Invited

      橋本彩加, 新堀佳紀, 根岸雄一

      分析化学68 ( 10 ) 769 - 776   7 2019

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      Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)   Publisher:日本分析化学会  

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    • チオラート保護金クラスターにおける配位子交換反応 Invited Peer-reviewed

      若山彰太, Hossain Sakiat, 藏重亘, 新堀佳紀, 根岸雄一

      ナノ学会会報15 ( 1 ) 7 - 13   11 2016

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      Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (other)   Publisher:ナノ学会  

      CiNii Article

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    • 逆相高速液体クロマトグラフィーによるチオラート保護金属ナノクラスターの高分解能分離 Invited Peer-reviewed

      新堀佳紀, 内田千紘, 藏重亘, 根岸 雄一

      ナノ学会会報14 ( 2 ) 57 - 64   3 2016

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      Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)   Publisher:ナノ学会  

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    • 金属クラスターの精密合成と水分解半導体光触媒の高機能化への応用 Invited

      新堀佳紀, 藏重亘, 根岸雄一

      セラミック51   781 - 784   2016

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      Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

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    • チオラート保護金属ナノクラスターの高分解能分離-逆相高速液体クロマトグラフィーの利用- Invited

      新堀佳紀, 根岸雄一

      ナノ学会会報13   29 - 35   10 2014

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      Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (other)  

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    Books and Other Publications

    Presentations

    • Determination of Equilibrium Constants in Ligand Binding-Dissociation Reactions of Ag29 Clusters Based on Photoluminescence Analysis Invited

      Yoshiki Niihori, Masaaki Mitsui

      ICPAC Yangon 2019  8 2019 

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      Language:English   Presentation type:Oral presentation (invited, special)  

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    • Effect of Dynamic Equilibrium of Binding-Dissociation of Ligands on Photoexcited State of Ligand-Protected Ag29 Cluster Invited

      Yoshiki Niihori, Masaaki Mitsui

      ICPAC Langkawi 2018  10 2018 

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      Language:English   Presentation type:Oral presentation (invited, special)  

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    • Precise Separation of Functionalized Thiolate-Protected Metal Clusters

      Yoshiki Niihori

      International Symposium on Smart Molecules and Materials  10 2017 

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      Language:English   Presentation type:Symposium, workshop panel (nominated)  

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    • Precise Separation of Thiolate-Protected Alloy Clusters Based on High Resolution Separation with Chromatography

      Yoshiki Niihori, Yuichi Negishi

      ISSPIC XVIII  8 2016 

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      Language:English   Presentation type:Poster presentation  

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    • The Understanding of Ligand Exchange Reaction Mechanism of Thiolate-Protected Metal Clusters by Usage of High-Resolution High-Performance Liquid Chromatography

      Yoshiki Niihori, Yuichi Negishi

      Pacifichem 2015  12 2015 

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      Language:English   Presentation type:Poster presentation  

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    • Mechanistic Insights of Ligand Exchange Reaction on Au24Pd(SR)18 by High-Performance Liquid Chromatography

      Yoshiki Niihori, Yoshihiro Kikuchi, Ayano Kato, Yuici Negishi

      ISMPC15  7 2015 

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      Language:English   Presentation type:Oral presentation (general)  

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    • Precise Separation of Metal Clusters Protected by Two-Types of Thiolate Ligands

      Yoshiki Niihori, Miku Matsuzaki, Chihiro Uchida, Yuichi Negishi

      ISSPIC XVII  9 2014 

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      Language:English   Presentation type:Poster presentation  

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    • Effect of Pd Doping on the Reactivity of Gold 25 Atom Cluster

      Yoshiki Niihori, Wataru Kurashige, Yuichi Negishi

      Gold 2012  9 2012 

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    Teaching Experience

    •  
      光物理化学 ( 立教大学理学部 )

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      化学ゼミナール ( 立教大学理学部 )

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    •  
      化学実験A ( 立教大学理学部 )

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      化学実験B ( 立教大学理学部 )

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      化学実験C ( 立教大学理学部 )

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      基礎化学実験 ( 立教大学理学部 )

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      物理化学演習 ( 立教大学理学部 )

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    Professional Memberships

    Research Projects

    • 平衡を考慮した配位子保護金属クラスターの発光特性の解明

      科学研究費助成事業 

      新堀佳紀

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      4 2020 - 3 2022

      Grant type:Competitive

      Grant amount:\4030000 ( Direct Cost: \3100000 、 Indirect Cost:\930000 )

      配位子保護金属クラスターは1原子精度での液相精密合成が可能であり、基幹ナノ材料として
      様々な応用が期待されている。しかしごく最近、溶液中の金属クラスターが配位子や金属原子が結
      合・解離を起こす動的平衡状態にあることが見出された。これまでの溶液中の配位子保護金属クラス
      ターの物性研究では、このような平衡の影響を全く考慮していないため、目的の構造・組成を有する
      クラスターの物性を厳密に評価できていない可能性がある。本研究では、申請者らが最近確立した
      “溶液中におけるクラスターの動的平衡を考慮した発光解析法”を種々の配位子保護金属クラスタ
      ー溶液系に適用し、溶液中で共存するクラスター平衡種毎の光物理パラメータ(発光量子収率、輻
      射速度定数、無輻射速度定数、光吸収断面積)や熱力学パラメータ(平衡定数、安定度定数、活性
      化エネルギー)を決定する。これによりクラスター組成・構造と光物性の真の対応関係を明らかにする
      ことを目的とする。

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    • 合金クラスターの超高分解能分離の実現と精密評価

      日本学術振興会  科学研究費助成事業 

      新堀佳紀

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      4 2016 - 3 2018

      Authorship:Principal investigator  Grant type:Competitive

      Grant amount:\3200000 ( Direct Cost: \2240000 、 Indirect Cost:\960000 )

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