Faculty Profiles - YAMAGUCHI, Shigehiro

Papers - YAMAGUCHI, Shigehiro

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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 Open Access

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 Open Access

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

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 Open Access

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

Open Access

Web of Science

PubMed

Photodissociation of B-N Lewis Adducts: A Partially Fused Trinaphthylborane with Dual Fluorescence Reviewed

Kyohei Matsuo, Shohei Saito, Shigehiro Yamaguchi

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 136 ( 36 ) page： 12580 - 12583 2014.9

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

The synthesis of a planarized trinaphthylborane with partially fused structure is presented. This compound shows not only high chemical and thermal stability but also sufficient Lewis acidity to form Lewis adducts with pyridine derivatives in solution. The BN Lewis adducts exhibit unprecedented photodissociation behavior in the excited state, reminiscent of the photogeneration of carbenium ions from triarylmethane leuco dyes. Consequently, these BN Lewis adducts exhibit dual fluorescence emission arising from the initial tetracoordinate BN adducts and the photodissociated tricoordinate boranes.

DOI： 10.1021/ja506980p

Web of Science

PubMed

Dearomatization-Induced Transannular Cyclization: Synthesis of Electron-Accepting Thiophene-S,S-Dioxide-Fused Biphenylene Reviewed

Aiko Fukazawa, Hiroya Oshima, Soji Shimizu, Nagao Kobayashi, Shigehiro Yamaguchi

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 136 ( 24 ) page： 8738 - 8745 2014.6

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

The transannular cyclization of dehydroannulenes bearing several alkyne moieties in close proximity is a powerful synthetic method for producing polyc-yclic aromatic hydrocarbons. We report that the reactivity can be switched by the aromaticity of the ring skeletons fused with the dehydroannulene core. Thus, while thiophene-fused bisdehydro[12]annulene 1 was handled as a stable compound in the air at room temperature, the oxidation with m-chloroperbenzoic acid from the aromatic thiophene rings to the nonaromatic thiophene-S,S-dioxides induced the transannular cyclization, even at room temperature, which was completed within 1 day to produce the formal [2 + 2] cycloadduct 3. This is in stark contrast to the fact that the thermal cyclization of 1 itself required heating at 80 C for 9 days for completion. Experimental and theoretical studies indicate that the oxidation of even one thiophene ring in 1 sufficiently decreases the activation barrier for the transannular cyclization that proceeds through the 8 pi and 4 pi electrocyclic reaction sequence. The thiophene-S,S-dioxide-fused biphenylene 3 thus produced exhibits a set of intriguing properties, such as a higher electron affinity (E-1/2 = -1.17 V vs Fc and Fc(+)) and a stronger fluorescence (Phi(F) = 0.20) than the other relevant biphenylene derivatives, which have electron-donating and nonfluorescent characteristics.

DOI： 10.1021/ja503499n

Web of Science

PubMed

A Strap Strategy for Construction of an Excited-State Intramolecular Proton Transfer (ESIPT) System with Dual Fluorescence Reviewed

N. Suzuki, A. Fukazawa, K. Nagura, S. Saito, H. Kitoh-Nishioka, D. Yokogawa, S. Irle, S. Yamaguchi

Angew. Chem. Int. Ed. Vol. 53 page： 8231-8235 2014.6

A Strap Strategy for Construction of an Excited-State Intramolecular Proton Transfer (ESIPT) System with Dual Fluorescence Reviewed

N. Suzuki, A. Fukazawa, K. Nagura, S. Saito, H. Kitoh-Nishioka, D. Yokogawa, S. Irle, S. Yamaguchi

Angew. Chem. Int. Ed. Vol. 53 page： 8231-8235 2014.6

Dearomatization-Induced Transannular Cyliczation: Synthesis of Electron-Accepting Thiophene-S,S-Dioxide-Fused Biphenylene Reviewed

A. Fukazawa, H. Oshima, S. Shimizu, N. Kobayashi, and S. Yamaguchi

J. Am. Chem. Soc. Vol. 136 page： 8738-8745 2014.6

Heterotriangulenes pi-Expanded at Bridging Positions Reviewed

Chih-Ming Chou, Shohei Saito, Shigehiro Yamaguchi

ORGANIC LETTERS Vol. 16 ( 11 ) page： 2868 - 2871 2014.6

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

A series of nitrogen-containing heterotriangulenes expanded at the bridging positions has been synthesized. Among them, a dibenzo[c,g]fluorenylidene-substituted derivative has a highly twisted conformation for the overcrowded alkene moieties, which impart a highly electron-accepting character to the electron-donating heterotriangulene skeleton and thereby an NIR absorption as well as multiredox properties with a low reduction potential.

DOI： 10.1021/ol501004g

Web of Science

PubMed

The B(C6F5)(3) Boron Lewis Acid Route to Arene-Annulated Pentalenes Reviewed

Chao Chen, Marcel Harhausen, Aiko Fukazawa, Shigehiro Yamaguchi, Roland Froehlich, Constantin G. Daniliuc, Jeffrey L. Petersen, Gerald Kehr, Gerhard Erker

CHEMISTRY-AN ASIAN JOURNAL Vol. 9 ( 6 ) page： 1671 - 1681 2014.6

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

4,5-Dimethyl-1,2-bis(1-naphthylethynyl)benzene (12) undergoes a rapid multiple ring-closure reaction upon treatment with the strong boron Lewis acid B(C6F5)(3) to yield the multiply annulated, planar conjugated -system 13 (50% yield). In the course of this reaction, a C6F5 group was transferred from boron to carbon. Treatment of 12 with CH3B(C6F5)(2) proceeded similarly, giving a mixture of 13 (C6F5-transfer) and the product 15, which was formed by CH3-group transfer. 1,2-Bis(phenylethynyl)benzene (8a) reacts similarly with CH3B(C6F5)(2) to yield a mixture of the respective C6F5- and CH3-substituted dibenzopentalenes 10a and 16. The reaction is thought to proceed through zwitterionic intermediates that exhibit vinyl cation reactivities. Some B(C6F5)(3)-substituted species (26, 27) consequently formed by in situ deprotonation upon treatment of the respective 1,2-bis(alkynyl)benzene starting materials (24, 8) with the frustrated Lewis pair B(C6F5)(3)/P(o-tolyl)(3). The overall formation of the C6F5-substituted products formally require HB(C6F5)(2) cleavage in an intermediate dehydroboration step. This was confirmed in the reaction of a thienylethynyl-containing starting material 21 with B(C6F5)(3), which gave the respective annulated pentalene product 23 that had the HB(C6F5)(2) moiety 1,4-added to its thiophene ring. Compounds12-14, 23, and 26 were characterized by X-ray diffraction.

DOI： 10.1002/asia.201400096

Web of Science

PubMed

Heterotriangulenes π-Expanded at Bridging Positions Reviewed

C. -M. Chou, S. Saito, S. Yamaguchi

Org. Lett. Vol. 16 page： 2868-2871 2014.5

Synthesis of Pyridine N-Oxide-BF2CF3 Complexes and Their Fluorescence Properties Reviewed

Tomoaki Nishida, Aiko Fukazawa, Eriko Yamaguchi, Hiroya Oshima, Shigehiro Yamaguchi, Motomu Kanai, Yoichiro Kuninobu

CHEMISTRY-AN ASIAN JOURNAL Vol. 9 ( 4 ) page： 1026 - 1030 2014.4

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

Pyridine N-oxide-BF2CF3 and -BF2C2F5 complexes and their derivatives were synthesized. Most of the complexes show fluorescence both in solution and in the solid state. By expanding the -conjugated skeleton, the color of the fluorescence could be changed dramatically. A fluorophore with a high solvent dependency could also be produced. Since such compounds can be synthesized on a gram scale in high yield, and are stable to oxygen, water, and heat, the complexes hold great potential as organic functional materials.

DOI： 10.1002/asia.201301688

Web of Science

PubMed

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Papers - YAMAGUCHI, Shigehiro