Faculty Profiles - SHINOKUBO, Hiroshi

Papers - SHINOKUBO, Hiroshi

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Bis-rhodium hexaphyrins: metalation of [28]hexaphyrin and a smooth Huckel aromatic-antiaromatic interconversion Reviewed International journal

Harapriya Rath, Naoki Aratani, Jong Min Lim, Jae Seok Lee, Dongho Kim, Hiroshi Shinokubo, Atsuhiro Osuka

CHEMICAL COMMUNICATIONS ( 25 ) page： 3762 - 3764 2009.5

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

Metalation of [28]hexaphyrin(1.1.1.1.1.1) with [RhCl(CO)(2)](2) resulted in the formation of an antiaromatic bis-Rh(I) complex, which can be oxidized to an aromatic bis-Rh(I) complex with retention of its rectangular structure.

DOI： 10.1039/b905859a

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Functionalization of Boron Dipyrrin (BODIPY) Dyes through Iridium and Rhodium Catalysis: A Complementary Approach to alpha- and beta-Substituted BODIPYs Reviewed International journal

Jinping Chen, Masatoshi Mizumura, Hiroshi Shinokubo, Atsuhiro Osuka

CHEMISTRY-A EUROPEAN JOURNAL Vol. 15 ( 24 ) page： 5942 - 5949 2009.5

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

Iridium-catalyzed direct borylation has been applied to meso-substituted dipyrromethane and boron dipyrrin (BODIPY) dyes. Borylation is highly regioselective and complementary: it occurs exclusively at the alpha position for meso-mesityldipyrromethane and at the beta positions for meso-mesityl BODIPY dye. This regioselective borylation enables a variety of alpha- and beta-substituted BODIPY dyes to be synthesized. Introduction of alpha,beta-enoate and alpha,beta,gamma,delta-dienoate functions into BODIPY dyes at the alpha or beta positions was achieved by rhodium-catalyzed Heck-type addition of the borylated compounds to acrylate and 2,4-pentadienoate esters. This functionalization has a significant effect on the electronic properties of BODIPY dyes, as seen in substantial redshift of the absorption and emission spectra. Comparative studies showed that the alpha- and beta-substituted series of BODIPY dyes show substantially different photophysical properties, and thus the importance of the position to be functionalized is highlighted.

DOI： 10.1002/chem.200802541

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Metathesis-like Splitting Reactions of Metallated [36]Octaphyrins(1.1.1.1.1.1.1.1): Experimental and Computational Investigations Reviewed International journal

Yasuo Tanaka, Hiroshi Shinokubo, Yosuke Yoshimura, Atsuhiro Osuka

CHEMISTRY-A EUROPEAN JOURNAL Vol. 15 ( 23 ) page： 5674 - 5685 2009.4

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

meso-Octakis(pentafluorophenyl)-substituted [36]octaphyrin(1.1.1.1.1.1.1.1) (1) is a figure-of-eight nonaromatic macrocycle that serves its a unique platform to induce a metathesis-like splitting reaction upon bis-Cu(II) metalation. To get a better understanding of this splitting reaction, we examined the metalation of 1 with several metal ions. In contrast with the smooth and quantitative splitting reaction of bis-Cu(II) complex 1-CuCu, free-base 1, mono-Cu(II) complex 1-Cu, and bis-Zi(II) complex 1-ZnZn do not undergo the splitting reaction. Mono-Con complex 1-Co was selectively produced from metalation with the Co(II) ion, from which hybrid complex 1-CoCu was synthesized. The hybrid complex 1-CoCu undergoes the splitting reaction to give 2-Co and 2-Cu quantitatively. Activation parameters of the splitting reactions were determined: E(a) = 104 kJ mol(-1), Delta H double dagger 101 kJ mol(-1), Delta S double dagger = -25.0 J mol(-1) K(-1), and Delta V double dagger = 18 cm(3)mol(-1) for 1-CuCu and E(a) = 105 kJ mol(-1), Delta H double dagger = 102 kJ mol(-1), and Delta S double dagger = -29.9 J mol(-1) K(-1) for 1-CoCu. A marked difference between the splitting reaction reactivity of 1-CuCu and 1-ZnZn has been examined by DFT calculations at the B3LYP/631SDD// B3LYP/LANL2DZ level, which revealed that the reaction proceeds through it stepwise route involving initial C1-C20 bond formation to give INT1 as the rate-determining step and subsequent C21-C40 bond formation to give a spirocyclobutane intermediate (INT2), followed by a radical reverse cycloaddition reaction to give two metalloporphyrins. Inherent instability of 1-CuCu, which may arise from its strongly distorted structure, was indicated to be a main factor in the smooth splitting reaction. Finally, a new bis-Pd(II) complex (5-PdPd) was isolated in the metalation of 1 with Pd(OAc)(2) in a 9:1 mixture of 2,2,2-trifluoroethanol and methanol as a manifestation of the transannular electronic interaction in metalated octaphyrin complexes. Collectively, these results underscore the importance of the transannular electronic interactions that are enhanced by metalation, depending upon the coordinated metal ions.

DOI： 10.1002/chem.200900454

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Conformational Changes of meso-Aryl Substituted Expanded Porphyrins upon Protonation: Effects on Photophysical Properties and Aromaticity Reviewed

Jae-Yoon Shin, Jong Min Lim, Zin Seok Yoon, Kil Suk Kim, Min-Chul Yoon, Satoru Hiroto, Hiroshi Shinokubo, Soji Shimizu, Atsuhiro Osuka, and Dongho Kim

J. Phys. Chem. B, Vol. 113 ( 17 ) page： 5794–5802 2009.4

Post-Modification of meso-meso-Linked Porphyrin Arrays by Iridium and Rhodium Catalyses for Tuning of Energy Gap Reviewed International journal

Jinping Chen, Naoki Aratani, Hiroshi Shinokubo, Atsuhiro Osuka

CHEMISTRY-AN ASIAN JOURNAL Vol. 4 ( 7 ) page： 1126 - 1133 2009.3

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

meso-meso-Linked diporphyrins fabricated with multiple unsaturated carboxylic acid groups are efficiently synthesized by the use of transition-metal catalysis. Iridium-catalyzed direct borylation of meso-meso-linked diporphyrins furnish multi-borylated diporphyrins with high regioselectivity. Then, the introduction of alpha,beta- or alpha,beta,gamma,delta-unsaturated ester functions to the diporphyrins is achieved through rhodium-catalyzed Heck-type addition of the borylated diporphyrins to acrylate or 2,4-pentadienoate esters. Saponification of the esters to the corresponding acids is accomplished in high yields. The post-modification of diporphyrin 6 smoothly provides a water-soluble multiporphyrin array 1 in 84% total yield in 3 steps. This functionalization significantly affects the electronic properties of the porphyrins, resulting in different energy levels of each porphyrin unit. The absorption and fluorescence spectra indicate efficient energy transfer in the porphyrin dimers.

DOI： 10.1002/asia.200900053

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First self-assembly study of large pi-conjugated corrole dimers on solid substrates Reviewed International journal

Xinrui Miao, Aimei Gao, Zhuomin Li, Satoru Hiroto, Hiroshi Shinokubo, Atsuhiro Osuka, Wenli Deng

APPLIED SURFACE SCIENCE Vol. 255 ( 11 ) page： 5885 - 5890 2009.3

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Our study focus on beta, beta'-doubly linked corrole dimers (CDs) on mica and Au(1 1 1) surface using samples prepared by the synthetic method described by Osuka group appeared on recent publication [S. Hiroto, K. Furukawa, H. Shinokubo, A. Osuka, J. Am. Chem. Soc. 128 (2006) 12380]. Atomic force microscopy (AFM) and scanning tunneling microscopy (STM) were used to investigate the self-assembled structure of corrole dimers adsorbed on mica and Au(1 1 1) surfaces respectively at room temperature in air. The CDs adopt a dissimilar adsorption modality due to the different surface free energy of the different substrates. These types of molecular layers provide a useful platform for the study of surface and interface phenomena outside a vacuum system. It is potentially useful for practical fabrication of molecular devices because of the simplicity of the sample preparation and the stability of the interface in ambient conditions. (C) 2009 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.apsusc.2009.01.026

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Adsorption characteristic of self-assembled corrole dimers on HOPG Reviewed International coauthorship International journal

Xinrui Miao, Aimei Gao, Satoru Hiroto, Hiroshi Shinokubo, Atsuhiro Osuka, Hongliang Xin, Wenli Deng

SURFACE AND INTERFACE ANALYSIS Vol. 41 ( 3 ) page： 225 - 230 2009.3

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

Our study first focus on two types of corrole dimers oxidized and reduced forms on highly oriented pyrolytic graphite (HOPG) surface. Scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and contact angle measurement (CAM) were used to investigate the self-assembled monolayers of corrole dimers adsorbed on HOPG surfaces at room temperature in air. XPS and CAM results have confirmed both two molecules adsorbed on an HOPG surface and formed self-assembled films, and STM experiments found that the corrole dimers adsorbed on HOPG surfaces form similar lobes. The different stable space structure of the oxidized form molecule (OFM) and reduced form molecule (RFM), led to the diversity of the tetramer structural dimensions. The occurrence of molecular aggregations and assembly was controlled by the interactions between molecular-molecular and molecule-substrate. The electrostatic interactions between the molecules control the geometrical sizes and molecule-substrate interactions determine topographical shapes of the self-assembled corrole dimers on HOPG surface. Copyright (C) 2009 John Wiley & Sons, Ltd.

DOI： 10.1002/sia.3011

Zwitterionic Corroles: Regioselective Nucleophilic Pyridination of a Doubly Linked Biscorrole Reviewed International journal

Satoru Hiroto, Naoki Aratani, Naoki Shibata, Yoshiki Higuchi, Takahiro Sasamori, Norihiro Tokitoh, Hiroshi Shinokubo, Atsuhiro Osuka

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 48 ( 13 ) page： 2388 - 2390 2009.2

Double Cleavage of sp(2) C-H and sp(3) C-H Bonds on One Metal Center: DMF-Appended Cyclometalated Platinum(II) and -(IV) Porphyrins Reviewed International journal

Shigeru Yamaguchi, Hiroshi Shinokubo, Atsuhiro Osuka

INORGANIC CHEMISTRY Vol. 48 ( 3 ) page： 795 - 797 2009.2

Adsorption Characteristic of Self-Assembled Corrole Dimers on HOPG Reviewed

Xinrui Miao, Aimei Gao, Satoru Hiroto, Hiroshi Shinokubo, Atsuhiro Osuka, Hongliang Xina, and Wenli Deng

Surf. Interface Anal. Vol. 41 page： 225–230 2009.1

Synthesis of Norbornane-Bridged Diporphyrins via Palladium-Catalyzed [3+2] Annulation Strategy Reviewed International journal

Masatoshi Mizumura, Hiroshi Shinokubo, Atsuhiro Osuka

SYNTHESIS-STUTTGART ( 1 ) page： 59 - 61 2009.1

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：GEORG THIEME VERLAG KG

The reaction of meso-bromoporphyrins with norbornene-fused porphyrins afforded novel norbornane-bridged diporphyrins in excellent yields via palladium-catalyzed [3+2] annulation reaction.

DOI： 10.1055/s-0028-1083267

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Marriage of porphyrin chemistry with metal-catalysed reactions Reviewed International journal

Hiroshi Shinokubo, Atsuhiro Osuka

CHEMICAL COMMUNICATIONS ( 9 ) page： 1011 - 1021 2009

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

The development of porphyrin synthesis by means of transition metal-catalyzed reactions is explored in this feature article. Porphyrins have been receiving much attention in a wide area of chemistry as functional dyes, non-linear optical materials, ligands for a variety of metals, structural motifs in supramolecules, and so forth. However, they have been merely recognized as a reaction substrate in transition metal-catalyzed transformations. Recently, application of such new methodologies to porphyrin synthesis has proven to be very powerful to create new types of porphyrinic compounds, which have their own intriguing structures and properties. New transformations on porphyrins via transition metal catalysis offer us prospects of new designs of architectures, thus facilitating further development of this important class of functional molecules.

DOI： 10.1039/b817941g

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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

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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

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Papers - SHINOKUBO, Hiroshi