KEIO RESEARCHERS INFORMATION SYSTEM

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Recent Advances in Quinoline-Based Macrocycles: Synthesis, Properties, and Applications in Catalytic Reactions

  Xu W., Kumagai N.

  Synthesis (Germany) （Synthesis (Germany))  56 （ 11 ） 1765 - 1774 2024.05

  Research paper (scientific journal), Accepted,  ISSN  00397881

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  Macrocyclic compounds exhibit unique properties due to their large ring-shaped structures, which have captivated chemists in recent decades. These molecules exert specific functions in various applicable fields, such as chemistry, materials science, and biology. Crown ethers, calixarenes, and porphyrinoids, which contain several ether/phenol/pyrrole subunits, represent these molecular categories with unparalleled functional diversity. In contrast, quinoline-based macrocycles comprising the quinoline unit as a key element to construct specific ring shapes have received limited attention. In this minireview, we summarize the recent advances in oligoquinoline macrocycles TriQuinoline (TQ), oxa-TriQuinoline (o-TQ), TEtraQuinoline (TEQ), and other bridged quinoline-based macrocycles. Emphasis is placed on the synthesis, structure, and application of these molecules in organometallic and supramolecular chemistry, which may guide new molecular designs in the quinoline-based macrocycle family. 1 Introduction 2 Quinoline-Based Macrocycles 2.1 TriQuinoline (TQ) 2.2 Oxa-TriQuinoline (o-TQ) 2.3 TEtraQuinoline (TEQ) 2.4 Larger Quinoline-Based Macrocycles with Bridges 3 Conclusion.

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• In2Q2: A New Entry of 16-Membered Tetraazamacrocycle Concatenating Indole and Quinoline Units

  Kihara K., Kobayashi T., Xu W., Kumagai N.

  Chemistry - A European Journal （Chemistry - A European Journal)  30 （ 25 ）  2024.05

  Research paper (scientific journal), Accepted,  ISSN  09476539

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  A new family of 16-membered macrocycles comprising two indole (In) and two quinoline (Q) units, coined In2Q2, was synthesized. Each unit is diagonally located and concatenated in a head-to-tail fashion, furnishing a non-flat saddle-shaped architecture with C2 symmetry. The synthetic protocol utilizing macrocyclic diamide as a pivotal precursor allowed us to access a series of In2Q2 derivatives bearing various substituents on the periphery. The In2Q2 derivatives and their Zn2+ complexes were emissive in both solution phase and solid state. While the entire architecture of In2Q2 is similar to that of quinoline tetramer TEtraQuinoline, a couple of contrasting physicochemical properties were revealed.

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• A brief introduction to highly symmetric N-heteroarene-based macrocycles

  Xu W., Kumagai N.

  Tetrahedron （Tetrahedron)  141 2023.07

  Research paper (scientific journal), Accepted,  ISSN  00404020

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  Nitrogen-containing macrocycles have attracted sustained attention because of their fascinating structures and extensive applications in organic chemistry, therapeutic developments, and materials science. The nitrogen atoms in the macrocycles play important roles in the interaction with metal cations or small molecules, endowing their potential in catalysis, fluorescent sensors, and host–guest chemistry. In this context, herein we summarize highly symmetric nitrogen-containing N3/N4/N6 macrocycles comprising pyrroles, pyridines, quinolines, and (iso)indoles as key N-heteroarenes. The direct and indirect connectivity of N-heteroarene subunits allows for the construction of both flat and non-flat cyclic architectures. The synthesis, structure, and properties of these macrocycles are highlighted.

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• TEtraQuinolines: A Missing Link in the Family of Porphyrinoid Macrocycles

  Xu W., Nagata Y., Kumagai N.

  Journal of the American Chemical Society （Journal of the American Chemical Society)  145 （ 4 ） 2609 - 2618 2023.02

  Research paper (scientific journal), Accepted,  ISSN  00027863

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  Porphyrin contains four inwardly oriented nitrogen atoms. It is arguably the most ubiquitous multifunctional naturally occurring macrocycle that has inspired the design of novel nitrogen-containing heterocycles for decades. While cyclic tetramers of pyrrole, indole, and pyridine have been exploited as macrocycles in this category, quinoline has been largely neglected as a synthon. Herein, we report the synthesis of TEtraQuinoline (TEQ) as a ‘missing link’ in this N4 macrocycle family. In TEQs, four quinoline units are concatenated to produce an S4-symmetric architecture. TEQs are characterized by a highly rigid saddle shape, wherein the lone-pair orbitals of the four nitrogen atoms are not aligned in a planar fashion. Nevertheless, TEQs can coordinate a series of transition-metal cations (Fe2+, Co2+, Ni2+, Cu2+, Zn2+, and Pd2+). TEQs are inherently fluorescence-silent but become strongly emissive upon protonation or complexation of Zn(II) cations (ϕ = 0.71). TEQ/Fe(II) complexes can catalyze dehydrogenation and oxygenation reactions with catalyst loadings as low as 0.1 mol %.

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• Azo-tagged C4N4 fluorophores: unusual overcrowded structures and their application to fluorescent imaging

  Kohei M., Takizawa N., Tsutsumi R., Xu W., Kumagai N.

  Organic and Biomolecular Chemistry （Organic and Biomolecular Chemistry)  21 （ 14 ） 2889 - 2893 2023.01

  Research paper (scientific journal), Accepted,  ISSN  14770520

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  The C4N4 fluorophore is an intense fluorescence emitter featuring a 2,5-diaminopyrimidine core comprising four carbon and four nitrogen atoms. A series of C4N4 derivatives was photochemically dimerized at the 5-amino group, furnishing overcrowded orthotetraaryl-substituted diaryl azo compounds with a characteristic skewed structure revealed by X-ray crystallography. The photo-quenched azo-C4N4s are useful for fluorescently visualizing cells under hypoxic conditions.

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• Strategic Exploration of Quinoline-Based Materials

  2022.04

  -

  2024.03

  MEXT,JSPS, Grant-in-Aid for Scientific Research, 若手研究, Principal investigator

Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• BACHELOR'S THESIS

  2024

• CHEMISTRY OF BIOACTIVE SUBSTANCES

  2024

• STUDY OF MAJOR FIELD (MOLECULAR DESIGN)

  2024

• SEMINAR (MOLECULAR DESIGN)

  2024

• RESEARCH FOR BACHELOR'S THESIS 1

  2024

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