Faculty Profiles - YAMAGUCHI, Shigehiro

Papers - YAMAGUCHI, Shigehiro

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Red-Emissive Polyphenylated BODIPY Derivatives: Effect of Peripheral Phenyl Groups on the Photophysical and Electrochemical Properties

A. Wakamiya, N. Sugita, and S. Yamaguchi

Chem. Lett. Vol. 37 page： 1094-1095 2008

Phosphonium- and borate-bridged zwitterionic ladder stilbene and its extended analogues Reviewed

Aiko Fukazawa, Hiroshi Yamada, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 47 ( 30 ) page： 5582 - 5585 2008

Disilylphenylene and tetrasilylphenylene as new building unit for highly fluorescent poly(aryleneethynylene)s

Azusa Iida, Kazuhiko Nagura, Shigehiro Yamaguchi

CHEMISTRY-AN ASIAN JOURNAL Vol. 3 ( 8-9 ) page： 1456 - 1464 2008

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

We report the synthesis and photophysical properties of poly(aryleneethynylene)s (PAEs) containing disilyl- or tetrasilyl-substituted phenylene as the key building unit. The fluorescence spectra of one of the PAEs, consisting of the diethynylbis(trimethylsilyl)phenylene and fluorenylene units, shows an intense blue emission with the maximum at 428 nm. The absolute quantum yield (0,) and the fluorescence lifetime (Phi(F)) are 0.92 and 0.39 ns, respectively. The calculated radiative decay rate constant (k(r)) from the singlet excited state, based on Phi(F) and tau(s), is 2.4 x 10(9) s(-1), which is extremely large for organic molecules. A series of silyl-substituted PAEs, including a tricyclic tetrasilylphenylene-containing polymer, also show intense emissions with large k(r) values. Theoretical calculations of the model systems with the bis(phenylethynyl)benzene skeleton reveal the general substituent effect of the silyl groups attached to the PAE skeleton.

DOI： 10.1002/asia.200800125

Web of Science

PubMed

2,5-Thienylene-bridged triangular and linear porphyrin trimers Reviewed

J. Song, S.Y. Jang, S. Yamaguchi, J. Sankar, S. Hiroto, N. Aratani, J.-Y. Shin, S. Easwaramoorthi, K.S. Kim, D. Kim, H. Shinokubo, A. Osuka

Angewandte Chemie - International Edition Vol. 47 ( 32 ) page： 6004 - 6007 2008

Kinetically stabilized dibenzoborole as an electron-accepting building unit

Atsushi Wakamiya, Kotaro Mishima, Kanako Ekawa, Shigehiro Yamaguchi

CHEMICAL COMMUNICATIONS ( 5 ) page： 579 - 581 2008

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

A synthetic route to a dibenzoborole, kinetically stabilized by the 2,4,6-tri-tert-butylphenyl group, was developed, and a series of pi-extended derivatives were synthesized, which show orange-red emissions and stable electrochemical redox properties.

DOI： 10.1039/b716107g

Web of Science

PubMed

Coplanar oligo(p-phenylenedisilenylene)s based on the octaethyl-substituted s-hydrindacenyl groups Reviewed

Aiko Fukazawa, Yongming Li, Shigehiro Yamaguchi, Hayato Tsuji, Kohei Tamao

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 129 ( 46 ) page： 14164 - + 2007.11

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

The silicon analogues of the oligo(p -phenylenevinylene)s (Si-OPVs) with highly planar structures have been synthesized using a newly developed ligand, the 1,1,3,3,5,5,7,7-octaethyl-s -hydrindacen-4-yl (Eind) group. Their X-ray crystal structures and spectroscopic data demonstrate that the pi-conjugation effectively extends over the Si-OPV framework. Notably, tetrasiladistyrylbenzene exhibits an orange fluorescence even at room temperature both in solution and in the solid state, which is attributable to the effective extension of conjugation. To the best of our knowledge, the tetrasiladistyrylbenzene is the first emissive Si=Si derivative even at room temperature.

DOI： 10.1021/ja0764207

Web of Science

PubMed

Thiophene- and selenophene-based heteroacenes: Combined quantum chemical DFT and spectroscopic Raman and UV-vis-NIR study

Reyes Malave Osuna, Rocio Ponce Ortiz, Toshihiro Okamoto, Yoshitake Suzuki, Shigehiro Yamaguchi, Victor Hernandez, Juan Teodomiro Lopez Navarrete

JOURNAL OF PHYSICAL CHEMISTRY B Vol. 111 ( 26 ) page： 7488 - 7496 2007.7

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

In this article, we report the characterization of a series of thiophene- and selenophene-based heteroacenes, materials with potential applications in organic electronics. In contrast to the usual alpha-oligothiophenes, these annelated oligomers have a larger band gap than most semiconductors currently used in the fabrication of organic field-effect transistors (OFETs) and therefore they are expected to be more stable in air. The synthesis of these fused-ring molecular materials was motivated by the notion that a more rigid and planar structure should reduce defects (such as torsion about single bonds between alpha-linked units or S-syn defects) and thus improve pi-conjugation for better charge-carrier mobility. The conjugational properties of these heteroacenes have been investigated by means of FT-Raman spectroscopy, revealing that pi-conjugation increases with the increasing number of annelated rings. DFT and TDDFT quantum chemical calculations have been performed, at the B3LYP/6-31G** level, to assess information regarding the minimum-energy molecular structure, topologies, and absolute energies of the frontier molecular orbitals around the gap, vibrational normal modes related to the main Raman features, and vertical one-electron excitations giving rise to the main optical absorptions.

DOI： 10.1021/jp067262t

Web of Science

PubMed

Energy migration in conjugated polymers: the role of molecular structure

Aimee Rose, John D. Tovar, Shigehiro Yamaguchi, Evgueni E. Nesterov, Zhengguo Zhu, Timothy M. Swager

PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES Vol. 365 ( 1855 ) page： 1589 - 1606 2007.6

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

Conjugated polymers undergo facile exciton diffusion. Different molecular structures were examined to study the role of the excited state lifetimes and molecular conformations on energy transfer. There is a clear indication that extended fluorescence lifetimes give enhanced exciton diffusion as determined by fluorescence depolarization measurements. These results are consistent with a strong electronic coupling or Dexter-type energy transfer as the dominating mechanism. The control of polymer conformations in liquid crystal solvents was also examined and it was determined that more planar conformations gave enhanced energy transfer to emissive low band-gap endgroups.

DOI： 10.1098/rsta.2007.2033

Web of Science

PubMed

Highly emissive poly(aryleneethynylene)s containing 2,5-diboryl-1,4-phenylene as a building unit

Cui-Hua Zhao, Atsushi Wakamiya, Shigehiro Yamaguchi

MACROMOLECULES Vol. 40 ( 11 ) page： 3898 - 3900 2007.5

Single-crystal field-effect transistors of benzoannulated fused oligothiophenes and oligoselenophenes

Koichi Yamada, Toshihiro Okamoto, Kenichi Kudoh, Atsushi Wakamiya, Shigehiro Yamaguchi, J. Takeya

APPLIED PHYSICS LETTERS Vol. 90 ( 7 ) page： 072102 2007.2

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

Recently synthesized benzoannulated fused oligothiophenes and oligoselenophenes are introduced as air-stable organic semiconductors for high-performance organic field-effect transistors. To evaluate electronic mobility intrinsic to the materials, the technique of single-crystal transistors is employed for two representative compounds of benzoannulated pentathienoacene f-B5TB and its selenium analog f-BT3STB. High mobility of approximately 1.1 cm(2)/V s is achieved for the selenium compound due to its considerable Se---Se orbital interactions. The materials simultaneously bear features of high mobility and high duration in ambient atmosphere. (c) 2007 American Institute of Physics.

DOI： 10.1063/1.2535617

Web of Science

Scopus

Ladder distyrylbenzenes with silicon and chalcogen bridges: Synthesis, structures, and properties

Kazuhiro Mouri, Atsushi Wakamiya, Hiroshi Yamada, Takashi Kajiwara, Shigehiro Yamaguchi

ORGANIC LETTERS Vol. 9 ( 1 ) page： 93 - 96 2007.1

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

A cascade-type anionic double cyclization of (o-silylphenyl)(o-halophenyl)acetylenes via lithiation followed by treatment with elemental chalcogen produces silicon and chalcogen-bridged stilbenes. Based on this reaction, a series of silicon and sulfur- or silicon and selenium-bridged ladder distyrylbenzenes have been synthesized. Their chemical modification by oxidation, crystal structures, and photophysical properties are described.

DOI： 10.1021/ol062615s

Web of Science

PubMed

General Synthesis of Extended Fused Oligothiophenes Consisting of Even Number of Thiophene Rings

T. Okamoto, K. Kudoh, A. Wakamiya, and S. Yamaguchi

Chem. Eur. J. Vol. 13 page： 548-556 2007

Thiophene and Selenophene-Based Heteroacenes: Combined Quantum Chemical DFT, and Spectroscopic Raman and UV-Vis-NIR Study

R. M. Osuna, R. P. Ortiz, T. Okamoto, Y. Suzuki, S. Yamaguchi, V. Hernandez, J. Teodomiro, and L. Navarrete

J. Phys. Chem. B Vol. 111 page： 7488-7496 2007

Highly Emissive Poly(aryleneethynylene)s Containing 2,5-Dibroyl-1,4-Phenylene as a Building Unit

C. -H. Zhao, A. Wakamiya, and S. Yamaguchi

Macromolecules Vol. 40 page： 3898-3900 2007

*3-Boryl-2,2'-Bithiophene as a Versatile Core Skeleton for Full-Color Highly Emissive Organic Solids

A. Wakamiya, K. Mori, and S. Yamaguchi

Angew. Chem. Int. Ed. Vol. 46 page： 4273-4276 2007

*Single Crystal Field Effect Transistors of Benzo-Annulated Fused Oligothiophenes and Oligoselenophenes

K. Yamada, T. Okamoto, K. Kudoh, A. Wakamiya, S. Yamaguchi, and J. Takeya

Appl. Phys. Lett. Vol. 90 page： 072102 2007

Crystallographic and Chiroptical Studies on Tetraarylferrocenes for Use as Chiral Rotary Modules for Molecular Machines

T. Muraoka, K. Kinbara, A. Wakamiya, S. Yamaguchi, and T. Aida

Chem. Eur. J. Vol. 13 page： 1724-1730 2007

Ladder Distyrylbenzenes with Silicon and Chalcogen Bridges: Synthesis, Structures, and Properties

K. Mouri, A. Wakamiya, H. Yamada, T. Kajiwara, and S. Yamaguchi

Org. Lett. Vol. 9 page： 93-96 2007

3-Boryl-2,2 '-bithiophene as a versatile core skeleton for full-color highly emissive organic solids

Atsushi Wakamiya, Kenji Mori, Shigehiro Yamaguchi

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 46 ( 23 ) page： 4273 - 4276 2007

Crystallographic and Chiroptical Studies on Tetraarylferrocenes for Use as Chiral Rotary Modules for Molecular Machines

T. Muraoka, K. Kinbara, A. Wakamiya, S. Yamaguchi, T. Aida

Chem. Eur. J. Vol. 13 page： 1724-1730 2007

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Papers - YAMAGUCHI, Shigehiro