Faculty Profiles - YAMAGUCHI, Shigehiro

Papers - YAMAGUCHI, Shigehiro

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A Benzophosphole P-Oxide with an Electron-Donating Group at 3-Position: Enhanced Fluorescence in Polar Solvents Reviewed

Eriko Yamaguchi, Aiko Fukazawa, Youhei Kosaka, Daisuke Yokogawa, Stephan Irle, Shigehiro Yamaguchi

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN Vol. 88 ( 11 ) page： 1545 - 1552 2015.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

Fluorophores with intramolecular charge-transfer (ICT) character in the excited state exhibit significant solvatochromism of their fluorescence. Here, we report an example for such compounds, a benzophosphole P-oxide bearing an electron-donating p-(diphenylamino)phenyl group at the 3-position. While this compound shows only subtle dependence of the absorption maximum on the solvent polarity (lambda(max) = 383-392 nm), its emission maximum is significantly red-shifted upon increasing the solvent polarity (cyclohexane: lambda(em) = 457 nm; DNIF: lambda(em) = 598 nm). Most notably, the fluorescence quantum yields gradually increase with increased Stokes shifts, ultimately reaching Phi(F) = 0.28 in DMF. This trend is fundamentally different from that observed for the corresponding 2-(diphenylamino)phenyl-substituted benzophosphole congener, for which applications as a fluorescent bioimaging probe were previously demonstrated. In this study, the origins of this striking difference are examined by a combined experimental and theoretical approach. Our results suggest that the observed difference arises from a significant contribution of quinoidal resonance forms in the ICT excited state, which suppresses nonradiative decay and hence increases the quantum yield in polar solvents.

DOI： 10.1246/bcsj.20150238

Web of Science

A Phosphole Oxide Based Fluorescent Dye with Exceptional Resistance to Photobleaching: A Practical Tool for Continuous Imaging in STED Microscopy Reviewed

C. Wang, A. Fukazawa, M. Taki, Yoshikatsu Sato, T. Higashiyama, S. Yamaguchi

Angew. Chem. Int. Ed. 2015.10

Designs of Functional pi-Electron Materials based on the Characteristic Features of Boron Reviewed

Atsushi Wakamiya, Shigehiro Yamaguchi

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN Vol. 88 ( 10 ) page： 1357 - 1377 2015.10

Language：Japanese Publisher：CHEMICAL SOC JAPAN

Boron, a group 13 element, has several characteristic structural and electronic features: 1) trivalent boron compounds usually adopt a trigonal planar geometry; 2) due to the presence of a vacant p-orbital, effective orbital interaction with pi-conjugated compounds is possible; 3) the presence of a vacant p-orbital is furthermore responsible for high Lewis acidity; 4) the boryl group acts as a pi-electron-accepting group particularly in the excited state. The consequent exploitation of these characteristic features of boron in the molecular design enables us to produce sophisticated pi-functional materials with attractive photophysical and electronic properties. This account article illustrates our systematic studies on the molecular design and the development of functional pi-electron materials using boron as a key element.

DOI： 10.1246/bcsj.20150151

Web of Science

Boron-Doped Nanographene: Lewis Acidity, Redox Properties, and Battery Electrode Performance Reviewed

S. Osumi, S. Saito, C. Dou, K. Matsuo, K. Kume, H. Yoshikawa, K. Awaga, S. Yamaguchi

Chem. Sci. 2015.9

Atomically-Controlled Substitutional Boron-Doping of Graphene Nanoribbons Reviewed

S. Kawai, S. Saito, S. Osumi, S. Yamaguchi, A. S. Foster, P. Spijker, E. Meyer

Nat. Commun. 2015.8

Benzophosphole P-Oxide with an Electron-Donating Group at 3-Position: Enhanced Fluorescence in Polar Solvents Reviewed

E. Yamaguchi, A. Fukazawa, Y. Kosaka, D. Yokogawa, S. Irle, S. Yamaguchi

2015.8

Atomically controlled substitutional boron-doping of graphene nanoribbons Reviewed

Shigeki Kawai, Shohei Saito, Shinichiro Osumi, Shigehiro Yamaguchi, Adam S. Foster, Peter Spijker, Ernst Meyer

NATURE COMMUNICATIONS Vol. 6 page： 8098 2015.8

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Boron is a unique element in terms of electron deficiency and Lewis acidity. Incorporation of boron atoms into an aromatic carbon framework offers a wide variety of functionality. However, the intrinsic instability of organoboron compounds against moisture and oxygen has delayed the development. Here, we present boron-doped graphene nanoribbons (B-GNRs) of widths of N = 7, 14 and 21 by on-surface chemical reactions with an employed organoboron precursor. The location of the boron dopant is well defined in the centre of the B-GNR, corresponding to 4.8 atom%, as programmed. The chemical reactivity of B-GNRs is probed by the adsorption of nitric oxide (NO), which is most effectively trapped by the boron sites, demonstrating the Lewis acid character. Structural properties and the chemical nature of the NO-reacted B-GNR are determined by a combination of scanning tunnelling microscopy, high-resolution atomic force microscopy with a CO tip, and density functional and classical computations.

DOI： 10.1038/ncomms9098

Web of Science

PubMed

A Nonaromatic Thiophene-Fused Heptalene and Its Aromatic Dianion Reviewed

Hiroya Oshima, Aiko Fukazawa, Takahiro Sasamori, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 54 ( 26 ) page： 7636 - 7639 2015.6

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

Heptalene, a nonaromatic, bicyclic 12 -electron system with a twisted structure, is of great interest with regard to its potential Huckel aromaticity in the two-electron oxidized or reduced forms. The synthesis of thiophene-fused heptalene 5 from the reductive transannular cyclization of bisdehydro[12]annulene 4, and its solid-state structure, which was confirmed by X-ray crystallographic analysis, is presented. Chemical reduction of 5 readily generated the corresponding dianion, which was successfully isolated as [(K[2.2.2]cryptand)(+)](2)5(2-). The X-ray crystallographic analysis of the dianion revealed a shallower saddle structure for the heptalene moiety and a lesser degree of bond alternation relative to 5. (HNMR)-H-1 spectroscopy exposed the effect of a diamagnetic ring current on dianion 5(2-), which was corroborated by nucleus-independent chemical shift (NICS) calculations. These results demonstrate that the heptalene dianion, containing 14 -electrons, does indeed exhibit pronounced degrees of Huckel aromaticity.

DOI： 10.1002/anie.201501790

Web of Science

PubMed

A Red-emitting Ratiometric Fluorescent Probe Based on a Benzophosphole P-Oxide Scaffold for the Detection of Intracellular Sodium Ions Reviewed

M. Taki, H. Ogasawara, H. Osaki, A. Fukazawa, Y. Sato, K. Ogasawara, T. Higashiyama, S. Yamaguchi

Chem. Commun. Vol. 51 page： 11880-11883 2015.6

A Planarized Triphenylborane Mesogen: Discotic Liquid Crystals with Ambipolar Charge-Carrier Transport Properties Reviewed

Tomokatsu Kushida, Ayumi Shuto, Masafumi Yoshio, Takashi Kato, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 54 ( 23 ) page： 6922 - 6925 2015.6

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

A discotic liquid-crystalline (LC) material, consisting of a planarized triphenylborane mesogen, was synthesized. X-ray diffraction analysis confirmed that this compound forms a hexagonal columnar LC phase with an interfacial distance of 3.57 angstrom between the discs. At ambient temperature, this boron-centered discotic liquid crystal exhibited ambipolar carrier transport properties with electron and hole mobility values of approximately 10(-3) and 3x10(-5)cm(2)V(-1)s(-1), respectively.

DOI： 10.1002/anie.201502678

Web of Science

PubMed

A Nonaromatic Thiophene-fused Heptalene and Its Aromatic Dianion Reviewed

H. Oshima, A. Fukazawa, T. Sasamori, S. Yamaguchi

Angew. Chem. Int. Ed. Vol. 54 page： 636-7639 2015.5

A Cyclic Octithiophene Containing β,β'-Linkages Reviewed

K. Asai, A. Fukazawa, S. Yamaguchi

Chem. Commun. Vol. 51 page： 6096-6099 2015.5

A Planarized Triphenylborane Mesogen: Discotic Liquid Crystals with Ambipolar Charge-Carrier Transport Properties Reviewed

T. Kushida, A. Shuto, M. Yoshio, T. Kato, S. Yamaguchi

Angew. Chem. Int. Ed. Vol. 54 page： 6922-6925 2015.4

Environment-Sensitive Fluorescent Probe: A Benzophosphole Oxide with an Electron-Donating Substituent Reviewed

Eriko Yamaguchi, Chenguang Wang, Aiko Fukazawa, Masayasu Taki, Yoshikatsu Sato, Taeko Sasaki, Minako Ueda, Narie Sasaki, Tetsuya Higashiyama, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 54 ( 15 ) page： 4539 - 4543 2015.4

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

Electron-donating aryl groups were attached to electron-accepting benzophosphole skeletons. Among several derivatives thus prepared, one benzophosphole oxide was particularly interesting, as it retained high fluorescence quantum yields even in polar and protic solvents. This phosphole-based compound exhibited a drastic color change of its fluorescence spectrum as a function of the solvent polarity, while the absorption spectra remained virtually unchanged. Capitalizing on these features, this phosphole-based compound was used to stain adipocytes, in which the polarity of subcellular compartments could then be discriminated on the basis of the color change of the fluorescence emission.

DOI： 10.1002/anie.201500229

Web of Science

PubMed

Environment-Sensitive Fluorescent Probe: A Benzophosphole Oxide with an Electron-Donating Substituent Reviewed

E. Yamaguchi, C. Wang, A. Fukazawa, M. Taki, Y. Sato, T. Sasaki, M. Ueda, N. Sasaki, T. Higashiyama, S. Yamaguchi

Angew. Chem. Int. Ed. Vol. 54 page： 4539-4543 2015.3

Highly Bent Crystals Formed by Restrained π-Stacked Columns Connected via Alkylene Linkers with Variable Conformations Reviewed

Highly Bent Crystals Formed by Restrained π-Stacked Columns Connected via Alkylene Linkers with Variable Conformations

Chem. Sci. Vol. 6 page： 2354-2359 2015.2

Fluorescent benzene-centered mono-, bis- and tris-triazapentadiene-boron complexes Reviewed

Christoph Glotzbach, Nadine Goedeke, Roland Froehlich, Constantin-Gabriel Daniliuc, Shohei Saito, Shigehiro Yamaguchi, Ernst-Ulrich Wuerthwein

DALTON TRANSACTIONS Vol. 44 ( 20 ) page： 9659 - 9671 2015

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

A series of novel benzene centered mono-, bis- and tris-1,3,5-triazapentadiene ligands 6a-e was synthesized and investigated with respect to their reactivity towards triphenylborane. The resulting blue-fluorescent boron complexes 14a-e with a six-membered ring chelate structure show excellent thermal and chemical stability. All title compounds were completely characterized including X-ray diffraction studies for 14a-c and 14e. Whereas the absorption spectra of all three classes of compounds are similar, the fluorescence spectra show distinct differences. Thus, the emission spectra of 14a, b show Stokes shifts of 4100-6700 cm(-1) with low quantum yields both in solution and in the solid state. However, the more bulky compounds 14c-e show markedly larger molar extinction coefficients and smaller bathochromic shifts compared to 14a,b. For all compounds, we observe significantly more intense red-shifted fluorescence in the solid state compared to that in dichloromethane solutions. For the interpretation of the absorption properties TD-DFT studies were performed based on DFT geometry optimizations.

DOI： 10.1039/c5dt00908a

Web of Science

Scopus

PubMed

Other Link： http://orcid.org/0000-0003-1863-9956

A cyclic octithiophene containing beta,beta '-linkages Reviewed

Kengo Asai, Aiko Fukazawa, Shigehiro Yamaguchi

CHEMICAL COMMUNICATIONS Vol. 51 ( 28 ) page： 6096 - 6099 2015

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

A cyclic octithiophene containing two beta,beta '-linkages was synthesized. Due to the large structural change in the excited state, this compound exhibited bathochromically shifted fluorescence. It also showed a small difference between the first and second oxidation potentials, indicative of spin delocalization through the beta,beta '-linkage in the one electron-oxidized state.

DOI： 10.1039/c5cc00570a

Web of Science

PubMed

A red-emitting ratiometric fluorescent probe based on a benzophosphole P-oxide scaffold for the detection of intracellular sodium ions Reviewed

Masayasu Taki, Hiroaki Ogasawara, Hiroshi Osaki, Aiko Fukazawa, Yoshikatsu Sato, Kimi Ogasawara, Tetsuya Higashiyama, Shigehiro Yamaguchi

CHEMICAL COMMUNICATIONS Vol. 51 ( 59 ) page： 11880 - 11883 2015

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

We disclose the development of a ratiometric fluorescent probe based on a benzophosphole P-oxide and its application for the detection of intracellular Na+ ions. Excitation by visible light induced red emission from this probe in water, which was subjected to a hypsochromic shift upon complexation with Na+. Based on this change, a ratiometric analysis enabled us to visualise changes in the Na+ concentration in living mammalian cells.

DOI： 10.1039/c5cc03547c

Web of Science

PubMed

Highly bent crystals formed by restrained pi-stacked columns connected via alkylene linkers with variable conformations Reviewed

Chih-Ming Chou, Shunpei Nobusue, Shohei Saito, Daishi Inoue, Daisuke Hashizume, Shigehiro Yamaguchi

CHEMICAL SCIENCE Vol. 6 ( 4 ) page： 2354 - 2359 2015

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

A reproducible formation of strongly bent crystals was accomplished by structurally restraining macrocyclic pi-conjugated molecules. The model pi-units consist of two 9,10-bis(2-thienylethynyl)anthracenes with a strong propensity for stacking, which are connected in a macrocyclic fashion via two alkylene linkers. The correlation between the crystalline morphology and the macrocyclic structures restrained by a variety of flexible alkylene linker combinations was systematically studied. Bent crystals were obtained only with specific alkylene linkers of appropriate chain length. The alkylene linkers can adopt different conformations in the crystal packing, so as to fill voids within the macrocycle. The ability to form several similar molecular structures with different alkylene conformations gives rise to contaminations of different crystalline phases within a single crystal, and it is these phase contaminations which are responsible for the bending of the crystals.

DOI： 10.1039/c4sc03849e

Web of Science

PubMed

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Papers - YAMAGUCHI, Shigehiro