Faculty Profiles - SHINOKUBO, Hiroshi

Papers - SHINOKUBO, Hiroshi

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Synthesis of a pyridine-fused porphyrinoid: oxopyridochlorin Reviewed International journal

Sumito Tokuji, Yuji Takahashi, Hideyuki Shinmori, Hiroshi Shinokubo, Atsuhiro Osuka

CHEMICAL COMMUNICATIONS ( 9 ) page： 1028 - 1030 2009

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

The treatment of 3,5-dibenzoylporphyrins with ammonium acetate provided novel oxopyridochlorins as the first examples of pyridine-fused porphyrinoids, which displayed absorption bands reaching into the near IR region and an ability to sensitize singlet oxygen effectively.

DOI： 10.1039/b819284g

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Synthesis of bithiophene-bridged cyclic porphyrin arrays Reviewed International journal

Osawa Kenta, Song Jianxin, Aratani Naoki, Shinokubo Hiroshi, Osuka Atsuhiro

Abstracts of Symposium on Physical Organic Chemistry Vol. 2009 ( 0 ) page： 242 - 242 2009

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Society of Physical Organic Chemistry, Japan

In most of cases the linkage of cyclic porphyrin arrays have been limited to phenylene- or ethynylene-bridges. Here we report the synthesis of novel cyclic porphyrin arrays including 2,2-bithiophene as a meso-to-meso spacer unit. The 1H-NMR spectra displayed the almost same chemical shifts for these cyclic porphyrin arrays except the slight shifts of thiophene proton, indicating high symmetric cyclic structure of them in solution. On the other hand, the X-ray diffraction analysis revealed the solid-state structure of cyclic 3mer Zn(II) complex which showed, to our surprise, the asymmetric conformation in which two of the bithiophene units were syn isomer and one of them was anti isomer. This isomerization of spacer units causes the molecule to apparently bend.

DOI： 10.11494/kisoyuki.2009.0.242.0

CiNii Research

Synthesis of Directly and Doubly Linked Dioxoisobacteriochlorin Dimers Reviewed International journal

Satoru Hiroto, Ichiro Hisaki, Hiroshi Shinokubo, Atsuhiro Osuka

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 130 ( 48 ) page： 16172 - 16173 2008.12

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

Oxidation of 2,18-diborylporphyrin provided 2,18-dihydroxyporphyrin, which shows solvent-dependent keto-enol tautomerism and dimerization through hydrogen bonding interaction in solution. Further oxidation of 2,18-dihydroxyporphyrins afforded doubly and directly linked dioxoisobacteriochlorin face-to-face dimers.

DOI： 10.1021/ja807659h

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Pt(II)- and Pt(IV)-Bridged Cofacial Diporphyrins via Carbon-Transition Metal sigma-Bonds Reviewed International journal

Shigeru Yamaguchi, Taisuke Katoh, Hiroshi Shinokubo, Atsuhiro Osuka

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 130 ( 44 ) page： 14440 - + 2008.11

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

A directly Pt(IV)-bridged cofacial diporphyrin has been synthesized by the cyclometalation reaction of beta-pyridylporphyrin with a Pt(IV) salt. Upon treatment with methylhydrazine, the Pt(IV) bridge is reduced to the Pt(II) center, resulting in a Pt(II)-bridged cofacial dimer with a helicity inversion of the complex as well as change in eletronic communication through the metal bridge.

DOI： 10.1021/ja8066385

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Unambiguous identification of Mobius aromaticity for meso-Aryl-substituted [28]hexaphyrins(1.1.1.1.1.1) Reviewed International journal

Jeyaraman Sankar, Shigeki Mori, Shohei Saito, Harapriya Rath, Masaaki Suzuki, Yasuhide Inokuma, Hiroshi Shinokubo, Kil Suk Kim, Zin Seok Yoon, Jae-Yoon Shin, Jong Min Lim, Yoichi Matsuzaki, Osamu Matsushita, Atsuya Muranaka, Nagao Kobayashi, Dongho Kim, Atsuhiro Osuka

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 130 ( 41 ) page： 13568 - 13579 2008.10

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

meso-Aryl-substituted [28]hexaphyrins(1.1.1.1.1.1) have been examined by (1)H, (13)C, and (19)F NMR spectroscopies, UV-vis absorption spectroscopy, magnetic circular dichroism spectroscopy, and single-crystal X-ray diffraction analysis. All of these data consistently indicate that [28]hexaphyrins(1.1.1.1.1.1) in solution at 25 degrees C exist largely as an equilibrium among several rapidly interconverting twisted Mobius conformations with distinct aromaticities, with a small contribution from a planar rectangular conformation with antiaromatic character at slightly higher energy. In the solid state, [28]hexaphyrins(1.1.1.1.1.1) take either planar or Mobius-twisted conformations, depending upon the meso-aryl substituents and crystallization conditions, indicating a small energy difference between the two conformers. Importantly, when the temperature is decreased to -100 degrees C in THF, these rapid interconversions among Mobius conformations are frozen, allowing the detection of a single [28]hexaphyrin(1.1.1.1.1.1) species having a Mobius conformation. Detailed analyses of the solid-state Mobius structures of compounds 2b, 2c, and 2f showed that singly twisted structures are achieved without serious strain and that cyclic pi-conjugation is well-preserved, as needed for exhibiting strong diatropic ring currents. Actually, the harmonic-oscillator model for aromaticity (HOMA) values of these structures are significantly large (0.85, 0.69, and 0.71, respectively), confirming the first demonstration of stable Mobius aromatic systems consisting of free-base expanded porphyrins without the assistance of metal coordination.

DOI： 10.1021/ja801983d

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Photoelectrochemical Properties of Doubly beta-Functionalized Porphyrin Sensitizers for Dye-Sensitized Nanocrystalline-TiO2 Solar Cells Reviewed International journal

Jong Kang Park, Hye Ryun Lee, Jinping Chen, Hiroshi Shinokubo, Atsuhiro Osuka, Dongho Kim

JOURNAL OF PHYSICAL CHEMISTRY C Vol. 112 ( 42 ) page： 16691 - 16699 2008.10

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

Functionalized porphyrins at meso- and beta-positions with different carboxylic acid groups were prepared to investigate electronic and photovoltaic properties as dye-sensitized nanocrystalline-TiO2 solar cells. The electronic structures of the porphyrin macrocyclic core are strongly coupled with olefinic side chains so that the absorption spectrum exhibits largely broad and red-shifted Soret and Q-bands, especially up to 475 nm at the Soret band in a porphyrin doubly functionalized with malonic diacid groups. Among porphyrin derivatives prepared in this study, 2b-bdta-Zn exhibits the maximum overall conversion efficiency of 3.03% and the maximum incident photon to current efficiency of 60. 1% in the Soret band region, superior to the others. From such photovoltaic performances, we can suggest that multiple pathways through olefinic side chains at two beta-positions enhance the overall electron injection efficiency and the moderate distance between the porphyrin sensitizer and the TiO2 semiconductor layer is important, retarding the charge recombination processes. As a consequence, these combined effects give rise to higher photovoltaic efficiency in photovoltaic regenerative solar cells.

DOI： 10.1021/jp804258q

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2,5-Thienylene-Bridged Triangular and Linear Porphyrin Trimers Reviewed

Jianxin Song, So Young Jang, Shigeru Yamaguchi, Jeyaraman Sankar, Satoru Hiroto, Naoki Aratani, Jae-Yoon Shin, Shanmugam Easwaramoorthi, Kil Suk Kim, Dongho Kim, Hiroshi Shinokubo, and Atsuhiro Osuka

Angew. Chem., Int. Ed. Vol. 47 page： 6004-6007 2008.7

Synthesis of Novel Chiral Porphyrins through Pd-Catalyzed [3 + 2] Annulation and Heterochiral Self-Assembling to Form Heterodimers Reviewed

Masatoshi Mizumura, Hiroshi Shinokubo, and Atsuhiro Osuka

Angew. Chem., Int. Ed. Vol. 47 page： 5387-5381 2008.6

Highly selective Ir-catalyzed direct sixfold borylation of peripheral aromatic substituents on hexakisaryl-substituted [28]hexaphyrin(1.1.1.1.1.1) Reviewed International journal

Goro Mori, Hiroshi Shinokubo, Atsuhiro Osuka

TETRAHEDRON LETTERS Vol. 49 ( 13 ) page： 2170 - 2172 2008.3

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Direct functionalization of aromatic substituents on [28]hexaphyrin was achieved by Ir-catalyzed borylation with the Smith-Miyaura-Hartwig protocol. High para. selectivity was observed in the reaction on 2,6-dichlorophenyl and 2,6-dimethoxyphenyl substituents of [28]hexaphyrin. The reaction with [26]hexaphyrin resulted only in reduction of the substrate to provide [28]hexaphyrin without borylation, thus highlighting the importance of the oxidation state of substrates in this catalytic transformation. The borylated hexaphyrin can be used for Suzuki-Miyaura cross-coupling reaction. (c) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2008.01.069

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Highly selective Ir-catalyzed direct sixfold borylation of peripheral aromatic substituents on hexakisaryl-substituted [28]hexaphyrin(1.1.1.1.1.1) Reviewed International journal

Mori Goro, Shinokubo Hiroshi, Osuka Atsuhiro

Tetrahedron Letters Vol. 49 ( 13 ) page： 2170 - 2172 2008.3

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

Direct functionalization of aromatic substituents on [28]hexaphyrin was achieved by iridium-catalyzed borylation with theSmith–Miyaura–Hartwig protocol. High para selectivity was observed in the reaction on 2,6-dichlorophenyl and 2,6-dimethoxyphenylsubstituents of [28]hexaphyrin. The reaction with [26]hexaphyrin resulted only in reduction of the substrate to provide [28]hexaphyrinwithout borylation, thus highlighting the importance of the oxidation state of substrates in this catalytic transformation. The borylatedhexaphyrin can be used for Suzuki–Miyaura cross coupling reaction.

CiNii Research

Dimeric assemblies from 1 2,3-triazole-appended Zn(II) porphyrins with control of NH-tautomerism in 1 2,3-triazole Reviewed International journal

Chihiro Maeda, Shigeru Yamaguchi, Chusaku Ikeda, Hiroshi Shinokubo, Atsuhiro Osuka

ORGANIC LETTERS Vol. 10 ( 4 ) page： 549 - 552 2008.2

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

Cu(I)-catalyzed 1,3-dipolar cycloaddition of meso-ethynyl Zn(II) porphyrin with benzyl azide efficiently provides meso-1-benzyl-1H-1,2,3-triazolyl Zn(II) porphyrin, which assembles to form a slipped cofacial dimer by the complementary coordination of the triazole nitrogen atom at the 3-position to the zinc center of a second porphyrin moiety both in the solid and solution states. Removal of the benzyl protection and introduction of a 2-ethoxycarbonylphenyl moiety greatly stabilize the dimeric assembly through an additional hydrogen bonding interaction between the NH proton of 2H-1,2,3-triazole and the carbonyl oxygen.

DOI： 10.1021/ol7028299

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meso-Aryl Substituted Rubyrin and Its Higher Homologues: Structural Characterization and Chemical Properties Reviewed

Soji Shimizu, Shohei Saito, Won-Seob Cho, Jonathan L. Sessler, Hiroshi Shinokubo, and Atsuhiro Osuka

Chem. Eur. J. Vol. 14 ( 9 ) page： 2668-2678 2008.2

Efficient Rhodium-Catalyzed installation of unsaturated ester functions onto porphyirins: Site-specific heck-type addition versus conjugate addition Reviewed International journal

Hiromi Baba, Jinping Chen, Hiroshi Shinokubo, Atsuhiro Osuka

CHEMISTRY-A EUROPEAN JOURNAL Vol. 14 ( 14 ) page： 4256 - 4262 2008

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

A facile introduction of alpha,beta-or alpha,beta,gamma,delta-unsaturated ester functions onto porphyrins was achieved through rhodium-catalyzed addition of beta-borylporphyrins to acrylate or 2,4-pentadienoate esters. The reaction of meso-borylporphyrins with acrylates exclusively afforded saturated esters by 1,4-conjugate addition under the same re-mode (Heck-type versus conjugate addition) is highly dependent on the reaction site (beta versus meso). This functionalization has a significant impact on the electronic properties of the pi system of porphyrins, which induces a substantial redshift and broadening in the absorption spectra by effective conjugation through the beta positions. The coplanar structure of the unsaturated ester moieties with respect to the porphyrin core has been unambiguously elucidated by X-ray crystallographic analysis.

DOI： 10.1002/chem.200701943

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Metalation of expanded porphyrins: A chemical trigger used to produce molecular twisting and Mobius aromaticity Reviewed International journal

Yasuo Tanaka, Shohei Saito, Shigeki Mori, Naoki Aratani, Hiroshi Shinokubo, Naoki Shibata, Yoshiki Higuchi, Zin Seok Yoon, Kil Suk Kim, Su Bum Noh, Jong Kang Park, Dongho Kim, Atsuhiro Osuka

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 47 ( 4 ) page： 681 - 684 2008

Synthesis of chiral porphyrins through Pd-catalyzed [3+2] annulation and heterochiral self-assembly Reviewed International journal

Masatoshi Mizumura, Hiroshi Shinokubo, Atsuhiro Osuka

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 47 ( 29 ) page： 5378 - 5381 2008

Unambiguous Identification of Mobius Aromaticity for meso-Aryl-Substituted [28]Hexaphyrins (1. 1. 1. 1. 1. 1) Reviewed International journal

HARAPRIYA Rath, 忍久保洋, 小林長夫

J. Am Chem. Soc. 130 page： 13568 - 13579 2008

Synthesis and Characterization of Pyridine-fused Porpyrinoid Reviewed International journal

Tokuji Sumito, Shinokubo Hiroshi, Osuka Atsuhiro

Abstracts of Symposium on Physical Organic Chemistry Vol. 2008 ( 0 ) page： 51 - 51 2008

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Society of Physical Organic Chemistry, Japan

The introduction of fused π-conjugated segments to porphyrin is expected to create a variety of conjugated porphyrin systems that would exhibit unique optical and electrochemical properties. We have previously reported the formation of dehydropurpurin from meso-bromoporphyrins in the presence of palladium catalyst and its conversion into 3,5-dibenzoylporphyrin by oxidation of the outer C-C double bond. This time we have found that pyridine-fused porphyrinoid was formed by the reaction of 3,5-dibenzoylporphyrin with ammonium acetate. The framework of this compound contains pyridine and carbonyl moieties. X-Ray crystallographic analysis unambiguously elucidated its structure. Both its structure and optical property will be presented.

DOI： 10.11494/kisoyuki.2008.0.51.0

CiNii Research

Synthesis of meso-5-Azaindolyl Appended Zn(II) Porphyrins via Pd-Catalyzed Annulation Reviewed

Chihiro Maeda, Hiroshi Shinokubo, and Atsuhiro Osuka

Org. Lett. Vol. 9 ( 13 ) page： 2493-2496 2007.6

Synthesis of Doubly β-to-β 1,3-Butadiyne-Bridged Diporphyrins: Enforced Planar Structures and Large Two-photon Absorption Cross Sections Reviewed

Ichiro Hisaki, Satoru Hiroto, Kil Suk Kim, Su Bum Noh, Dongho Kim, Hiroshi Shinokubo, and Atsuhiro Osuka

Angew. Chem., Int. Ed. Vol. 46 ( 27 ) page： 5125-5128 2007.6

Regioselective Borylation of Porphyrins via C-H Bond Activation under Iridium Catalysis That Affords Useful Building Blocks for Porphyrin Assemblies Reviewed

Hiroshi Hata, Shigeru Yamaguchi, Goro Mori, Satomi Nakazono, Taisuke Katoh, Keishi Takatsu, Satoru Hiroto, Hiroshi Shinokubo, and Atsuhiro Osuka

Chem. Asian J. Vol. 2 ( 7 ) page： 849-859 2007.5

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Papers - SHINOKUBO, Hiroshi