Faculty Profiles - YAMAGUCHI, Shigehiro

Papers - YAMAGUCHI, Shigehiro

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Boron-Containing PAH as a Substructure of Boron-Doped Graphene Reviewed

C. Dou, S. Saito, K. Matsuo, I. Hisaki, and S. Yamaguchi

Angew. Chem. Int. Ed. Vol. 51 page： 12206-12210 2012.10

TICT Fluorescence of N-borylated 2,5-Diarylpyrroles: A Gear Like Dual Motion in the Excited State Reviewed

T. Taniguchi, J. Wang, S. Irle, and S. Yamaguchi

Dalton Trans. Vol. 42 page： 620-624 2012.10

Polycyclic pi-Electron System with Boron at Its Center Reviewed

Shohei Saito, Kyohei Matsuo, Shigehiro Yamaguchi

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 134 ( 22 ) page： 9130 - 9133 2012.6

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

We disclose a new planarized triarylborane in which the tri-coordinated boron atom is embedded in a fully fused polycyclic pi-conjugated skeleton. The compound shows high stability toward oxygen, water, and silica gel, despite the absence of steric protection around the B atom. Reflecting the electron-donating character of the pi-skeleton and the electron-accepting character of the B atom, this compound shows broad absorption bands that cover the entire visible region and a fluorescence in the visible/near-IR region. In addition, this compound shows dramatic property changes upon formation of a tetra-coordinated borate, such as thermochromic behavior in the presence of pyridine.

DOI： 10.1021/ja3036042

Web of Science

PubMed

Elucidation of p-Conjugation Modes in Diarene-Fused 1,2-Dihydro-1,2-diborin Dianions Reviewed

Takafumi Araki, Atsushi Wakamiya, Kenji Mori, Shigehiro Yamaguchi

CHEMISTRY-AN ASIAN JOURNAL Vol. 7 ( 7 ) page： 1594 - 1603 2012.6

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

A series of diarene-fused 1,2-dihydro-1,2-diborins were prepared as a new B?B-bond-embedded polycyclic p-electron system. The reduction of these compounds with metals produced their corresponding dianions, the p-conjugation modes of which varied from 6p-conjugation within the central 1,2-diborin skeleton to 14p peripheral conjugation over the tricyclic skeleton, depending on the nature of the reduced biaryl framework. Moreover, the countercation to the dianions had a significant effect on the absorption spectra, with a dramatic color change from yellow to deep blue, depending on the distance between the tricyclic dianion skeleton and the countercation.

DOI： 10.1002/asia.201200055

Web of Science

PubMed

Polycyclic π-Electron System with Boron at Its Center Reviewed

S. Saito, K. Matsuo, and S. Yamaguchi

J. Am. Chem. Soc. Vol. 134 page： 9130-9133 2012.5

Preparation of Dihydroborole Derivatives by a Simple 1,1-Carboboration Route

Andreas Feldmann, Azusa Iida, Roland Froehlich, Shigehiro Yamaguchi, Gerald Kehr, Gerhard Erker

ORGANOMETALLICS Vol. 31 ( 6 ) page： 2445 - 2451 2012.3

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

2,3-Dihydroboroles are readily formed by treatment of dicyclopropylacetylene with the strongly electrophilic borane B(C6F5)(3). The reaction involves a sequence of 1,1-carboboration reactions and proceeds via dienylborane intermediates. Consistent with this, the reaction of the conjugated enyne 15c with B(C6F5)(3) leads to the formation of a dihydroborole.

DOI： 10.1021/om300065m

Web of Science

Planarized Triarylboranes: Stabilization by Structural Constraint and Their Plane-to-Bowl Conversion Reviewed

Zhiguo Zhou, Atsushi Wakamiya, Tomokatsu Kushida, Shigehiro Yamaguchi

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 134 ( 10 ) page： 4529 - 4532 2012.3

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

Triphenylborane and 9,10-diphenyl-9,10-dihydro-9,10-diboraanthracene, constrained to a planar arrangement with methylene tethers, were synthesized by intramolecular multi-fold Friedel-Crafts cyclization. These compounds were stable toward air, water, and amines, despite the absence of steric protection in the vertical direction with respect to the B atoms, and showed characteristic structural, electronic, and photophysical properties. In addition, upon treatment with a fluoride ion, these compounds underwent a plane-to-bowl conversion in a controlled manner.

DOI： 10.1021/ja211944q

Web of Science

PubMed

Synthesis and Photophysical Properties of Aryl-Substituted 2-Borylbenzaldimines and Their Extended pi-Conjugated Congeners Reviewed

Benedikt Neue, Roland Froehlich, Birgit Wibbeling, Aiko Fukazawa, Atsushi Wakamiya, Shigehiro Yamaguchi, Ernst-Ulrich Wuerthwein

JOURNAL OF ORGANIC CHEMISTRY Vol. 77 ( 5 ) page： 2176 - 2184 2012.3

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

Novel N-aryl-substituted 2-borylbenzaldimines 6 and related systems with extended pi-framework 7 based on two borylbenzaldimine units linked by a spacer moiety were synthesized by condensation reactions of 2-(dimesitylboryl)benzaldehyde 3 with various amines 4 and diamines 5. All compounds were completely characterized including X-ray diffraction, especially in view of Lewis acid-base B-O and B-N interactions. The electronic as well as the photophysical properties of bisimines 7 were determined using cyclic voltammetry, UV/vis, and fluorescence spectroscopy and quantum chemistry. These compounds feature large Stokes shifts and reversible reduction waves. Interestingly, UV irradiation experiments unfold enhanced photostability for compounds 7 with an extended pi-skeleton. By use of 1,8-diaminonaphthalene we observed the formation of a hitherto unknown BN-heterocyclic compound 9 fused with a perimidine skeleton. Structural and energetic aspects were evaluated by high level quantum chemical methods (DFT and SCS-MP2-calculations).

DOI： 10.1021/jo202212s

Web of Science

PubMed

Planarized Triarylboranes: Stabilization by Structural Constraint and Their Plane-to-Bowl Conversion Reviewed

Z. Zhou, A. Wakamiya, T. Kushida, and S. Yamaguchi

J. Am. Chem. Soc. Vol. 134 page： 4529-4532 2012.2

Substituent Effects on Twisted Internal Charge Transfer Excited States of N-Borylated Carbazoles and (Diphenylamino)boranes

Jian Wang, Ying Wang, Takuhiro Taniguchi, Shigehiro Yamaguchi, Stephan Irle

JOURNAL OF PHYSICAL CHEMISTRY A Vol. 116 ( 4 ) page： 1151 - 1158 2012.2

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

N-Boryl-substituted carbazoles (carBR(2)) and (diphenylamino)boranes (Ph2NBR2) with R = Mes (mesityl) and FMes [tris(trifluoromethyl)phenyl] substituents on boron exhibit large UV/vis Stokes shifts. To investigate the substituent effect on the magnitude of the Stokes shifts, we studied the electronic structure and spectroscopic properties of carBR(2) and Ph2NBR2 with R = H, Mes, and FMes using hybrid density functional theory (B3LYP) and time-dependent density functional theory (TD-B3LYP) for ground and low-lying excited states. The lowest lying excited state with a nonvanishing oscillator strength is a twisted internal charge transfer (TICT) (1)A state in the C-2 point group, owing to a single-electron excitation from the nitrogen lone pair to the unoccupied boron p(z) AO, Nlp -> Bp(z). Emission from these (1)A excited states are predicted to be much brighter than from the energetically close B-1 excited states that are not directly related to CT excitation from N to B, due to symmetry. An analysis of geometrical relaxations in the excited state and the state energies relative to the ground state energy of the equilibrium geometry reveals that (a) the carbazole skeleton induces a general red shift in UV/vis spectra, (b) bulky boryl substituents reduce the predicted Stokes shifts of TICT states, and (c) the presence of electron-withdrawing functional groups induces a further general red shift in UV/vis spectra but does not significantly alter Stokes shifts.

DOI： 10.1021/jp209264j

Web of Science

PubMed

Facile Synthesis of Biphenyl-Fused BODIPY and Its Property Reviewed

Yosuke Hayashi, Naoki Obata, Masatomo Tamaru, Shigeru Yamaguchi, Yutaka Matsuo, Akinori Saeki, Shu Seki, Yuka Kureishi, Shohei Saito, Shigehiro Yamaguchi, Hiroshi Shinokubo

ORGANIC LETTERS Vol. 14 ( 3 ) page： 866 - 869 2012.2

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

A biphenyl-fused BODIPY was synthesized through a facile oxidative cyclization of peripheral aryl-substituents at the beta-position of the BODIPY unit. The extended pi-system of the fused BODIPY induces near-infrared (NIR) absorption and strong pi-pi interactions in the solid state. These features are beneficial for the application of the dye as a functional material. The biphenyl-fused BODIPY dye was demonstrated to exhibit photocurrent conversion ability on the basis of its n-type semiconducting property.

DOI： 10.1021/ol2033916

Web of Science

Scopus

PubMed

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

Planarized B-phenylborataanthracene anions: structural and electronic impacts of coplanar constraint Reviewed

Tomokatsu Kushida, Zhiguo Zhou, Atsushi Wakamiya, Shigehiro Yamaguchi

CHEMICAL COMMUNICATIONS Vol. 48 ( 87 ) page： 10715 - 10717 2012

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

Potassium and lithium salts of anionic B-phenylborataanthracenes, whose phenyl groups were fixed in a coplanar fashion, were synthesized. These compounds exhibited solvent-separated ion pair structures both in the crystalline state and in solution. Planarization of the phenyl moiety had a remarkable impact on the photophysical properties, such as the red-shifted absorption and intense fluorescence.

DOI： 10.1039/c2cc35874c

Web of Science

PubMed

J-GLOBAL

Heteroarene-fused boroles: what governs the antiaromaticity and Lewis acidity of the borole skeleton?

Azusa Iida, Anna Sekioka, Shigehiro Yamaguchi

CHEMICAL SCIENCE Vol. 3 ( 5 ) page： 1461 - 1466 2012

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

A series of benzoheteroarene-fused boroles, containing pyrrole, furan, and thiophene as the heteroarene rings, were synthesized and their structures were determined by X-ray crystallographic analysis. Their antiaromaticity was assessed by calculations of the nucleus-independent chemical shift (NICS) values using the geometries derived from their crystal structures. The large NICS(1)(zz) values of the borole ring in the heteroarene-fused structures showed their high antiaromaticity, in contrast to the fact that dibenzoborole has a reduced antiaromaticity. This enhanced antiaromaticity is due to the lower extent of bond alternation in the borole ring with the heteroarene-fused structures compared to that in the parent borole. Theoretical calculations also indicated that the antiaromatic character of the borole is relevant to its LUMO level. Moreover, the experimentally evaluated Lewis acidities of the heteroarene-fused boroles are linearly correlated to their reduction potentials, namely, the LUMO levels. These results shed light on the understanding of how the fused-structures affect the properties and reactivities of the borole moiety. All the heteroarene-fused boroles have broad absorption bands with the comparable absorption maxima around 468-479 nm. In contrast, their reduction potentials are different from one another, dependent on the electronic characteristics of the heteroarene rings.

DOI： 10.1039/c2sc20100c

Web of Science

High-performance organic field-effect transistors based on dihexyl-substituted dibenzo[d,d ']thieno[3,2-b;4,5-b ']dithiophene

Yasuo Miyata, Eiji Yoshikawa, Takeo Minari, Kazuhito Tsukagoshi, Shigehiro Yamaguchi

JOURNAL OF MATERIALS CHEMISTRY Vol. 22 ( 16 ) page： 7715 - 7717 2012

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

A novel thienoacene compound, dihexyl-substituted dibenzo[d,d']thieno[3,2-b;4,5-b']dithiophene (C6-DBTDT), is developed as a p-type organic semiconductor for high-performance organic field-effect transistors. Insertion of an acceptor material at the contact interface enables substantial reduction in the threshold voltage and hysteresis behavior, and the field-effect mobilities of 2.5 and 3.1 cm(2) V-1 s(-1) are achieved for the C6-DBTDT film vacuum-deposited at room temperature and 80 degrees C, respectively.

DOI： 10.1039/c2jm30840a

Web of Science

Highly Flexible pi-Expanded Cyclooctatetraenes: Cyclic Thiazole Tetramers with Head-to-Tail Connection Reviewed

Kazuhiro Mouri, Shohei Saito, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 51 ( 24 ) page： 5971 - 5975 2012

Macrocyclic Restriction with Flexible Alkylene Linkers: A Simple Strategy to Control the Solid-State Properties of pi-Conjugated Systems Reviewed

Shohei Saito, Ken Nakakura, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 51 ( 3 ) page： 714 - 717 2012

N-Heterocyclic Carbene Boranes as Electron-Donating and Electron-Accepting Components of pi-Conjugated Systems Reviewed

Kazuhiko Nagura, Shohei Saito, Roland Froehlich, Frank Glorius, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 51 ( 31 ) page： 7762 - 7766 2012

Electron-Donating Tetrathienyl-Substituted Borole Reviewed

Takafumi Araki, Aiko Fukazawa, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 51 ( 22 ) page： 5484 - 5487 2012

Combined experimental and theoretical studies on the photophysical properties of cycloparaphenylenes Reviewed

Yasutomo Segawa, Aiko Fukazawa, Sanae Matsuura, Haruka Omachi, Shigehiro Yamaguchi, Stephan Irle, Kenichiro Itami

ORGANIC & BIOMOLECULAR CHEMISTRY Vol. 10 ( 30 ) page： 5979 - 5984 2012

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

We studied the UV-vis absorption and fluorescence in solution/solid states of [n]cycloparaphenylene ([n] CPP: n = 9, 12, 14, 15, and 16), and conducted theoretical studies to better understand the experimental results. The representative experimental findings include (i) the most intense absorption maxima (lambda(abs1)) display remarkably close values (338-339 nm), (ii) the longest-wavelength absorption maxima (lambda(abs2)) are blue-shifted with increasing the ring size (395 --> 365 nm), (iii) the emission maxima (lambda(em)) are blue-shifted with increasing the ring size (494 --> 438 nm for longest-wavelength maxima), (iv) the fluorescent quantum yields (Phi(F)) in solution are high (0.73-0.90), (v) the fluorescence lifetimes (tau(s)) of [9]- and [12] CPP are 10.6 and 2.2 ns, respectively, and (vi) the Phi(F) values slightly increase in polymer matrix but significantly decrease in the crystalline state. According to TD-DFT calculations, the longest-wavelength absorption (lambda(abs2)) corresponds to a forbidden HOMO --> LUMO transition and the most intense absorption (lambda(abs1)) corresponds to degenerate HOMO - 1 --> LUMO and HOMO --> LUMO + 1 transitions with high oscillator strength. The interesting and counterintuitive optical properties of CPPs (constant lambda(abs1) and blue shift of lambda(abs2)) could be ascribed mainly to the ring-size effect in frontier molecular orbitals (in particular the increase of the HOMO-LUMO gap as the number of benzene rings increases). On the basis of comparative calculations using hypothetical model geometries, we conclude that the unique behavior of HOMO and LUMO of CPPs is due mainly to their lack of a conjugation length dependence in combination with a significant bending effect (particularly to HOMO) and a torsion effect (particularly to LUMO).

DOI： 10.1039/c2ob25199j

Web of Science

PubMed

A Boron-Containing PAH as a Substructure of Boron-Doped Graphene Reviewed

Chuandong Dou, Shohei Saito, Kyohei Matsuo, Ichiro Hisaki, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 51 ( 49 ) page： 12206 - 12210 2012

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Papers - YAMAGUCHI, Shigehiro