| 1. |
Nakano, Tatsuya; Abe, Tsukasa; Matsumoto, Takahiro;* Kimura, Kento; Nakamura, Genta; Hayami, Shinya; Shiota, Yoshihito;* Yoshizawa, Kazunari;* Ogo, Seiji.*, Light-Driven Oxidation of CH4 to C1 Chemicals Catalysed by an Organometallic Ru Complex with O2., RSC Adv., 12, 20, 12253-12257, 2022.04.  |
| 2. |
Matsumoto, Takahiro., Smart Design of Organometallic Catalysts to Induce Innovative Material Transformations. , J. Jpn. Petrol. Inst. , 65, 4, 134-139, 2022.03. |
| 3. |
Isegawa, Miho;* Matsumoto, Takahiro; Ogo, Seiji. , Hydrogen Evolution, Electron-transfer, Hydride-Transfer Reactions in a Nickel-Iron Hydrogenase Model Complex: A Theoretical Study of the Distinctive Reactivities for the Conformational Isomers of Nickel-Iron Hydride.
2021, Dalton Trans., 51, 1, 312-323, 2021.12. |
| 4. |
Yatabe, Takeshi; Tome, Tamon; Takahashi, Yukina; Matsumoto, Takahiro; Yoon, Ki-Seok; Nakai, Hidetaka; Ogo, Seiji.* , C–H Arylation of Benzene with Aryl Halides using H2 and a Water-Soluble Rh-Based Electron Storage Catalyst., Chem. Eur. J., 27, 69, 17326-17330., 2021.10. |
| 5. |
Isegawa, Miho;* Matsumoto, Takahiro; Ogo, Seiji. , H2 Activation by Hydrogenase-Inspired NiFe Catalyst Using Frustrated Lewis Pair: Effect of Buffer and Halide Ion in the Heterolytic H–H Bond Cleavage.
, RSC Adv.
, 11, 45, 28420-28432., 2021.08. |
| 6. |
Yatabe, Takeshi; Kamitakahara, Kazuki; Higashijima, Kaede; Ando, Tatsuya; Matsumoto, Takahiro; Yoon, Ki-Seok; Enomoto, Takao; Ogo, Seiji., Synthesis of acetic acid from CO2, CH3I and H2 using a Water-Soluble Electron Storage Catalyst. , Chem. Commun., 10.1039/d1cc01611c, 57, 39 , 4772-4774, 2021.05. |
| 7. |
Ogo, Seiji; Thi Minh, Le Tu; Kikunaga, Takahiro; Ando, Tatsuya; Matsumoto, Takahiro; Yatabe, Takeshi; Kato, Kenji., Direct Synthesis of Hydrogen Peroxide in Water by Means of a Rh-Based Catalyst., Organometallics, 10.1021/acs.organomet.0c00565, 39, 20, 3731-3741, 2020.10. |
| 8. |
Ogo, Seiji; Ando, Tatsuya; Thi Minh, Le Tu; Mori, Yuki; Matsumoto, Takahiro; Yatabe, Takeshi; Yoon, Ki-Seok; Sato, Yukio; Hibino, Takashi; Kaneko, Kenji., A NiRhS Fuel Cell Catalyst – Lessons from Hydrogenase., Chem. Commun., 10.1039/d0cc04789a, 56, 79, 11787-11790, 2020.09. |
| 9. |
Ogo, Seiji; Kishima, Takahiro; Yatabe, Takeshi; Miyazawa, Keishi; Yamasaki, Ryunosuke; Matsumoto, Takahiro; Ando, Tatsuya; Kikkawa, Mitsuhiro; Isegawa, Miho; Yoon, Ki-Seok; Hayami, Shinya., [NiFe], [FeFe], and [Fe] Hydrogenase Models from Isomers., Sci. Adv., 10.1126/sciadv.aaz8181, 6, 24, eaaz8181.-eaaz8181., 2020.03, 水素の合成や分解を担う３種類の天然ヒドロゲナーゼ酵素の構造をヒントに１つの新しい触媒を開発した。今回開発した触媒は、同じ分子式で構造だけが異なる３種類の異性体によって、３種類のヒドロゲナーゼ酵素のように（i）燃料電池の水素電極の触媒（ii）水素製造の触媒（iii）化学工業の水素化の触媒として働くことを発見した。本研究成果は、これまで不明であったヒドロゲナーゼ酵素の触媒反応と触媒の分子構造との関係を解き明かすことで、次世代のエネルギー源である水素を効率よく利用する道を開いた。. |
| 10. |
Miho Isegawa, Takahiro Matsumoto, Seiji Ogo, Selective Oxidation of H2 and CO by NiIr Catalyst in Aqueous Solution
A DFT Mechanistic Study, Inorganic chemistry, 10.1021/acs.inorgchem.9b02400, 59, 2, 1014-1028, 2020.01, One of the challenges in utilizing hydrogen gas (H2) as a sustainable fossil fuel alternative is the inhibition of H2 oxidation by carbon monoxide (CO), which is involved in the industrial production of H2 sources. To solve this problem, a catalyst that selectively oxidizes either CO or H2 or one that co-oxidizes H2 and CO is needed. Recently, a NiIr catalyst [NiIICl(X)IrIIICl(Ε5-C5Me5)], (X = N,N′-dimethyl-3,7-diazanonane-1,9-dithiolate), which efficiently and selectively oxidizes either H2 or CO depending on the pH, has been developed (Angew. Chem. Int. Ed. 2017, 56, 9723-9726). In the present work, density functional theory (DFT) calculations are employed to elucidate the pH-dependent reaction mechanisms of H2 and CO oxidation catalyzed by this NiIr catalyst. During H2 oxidation, our calculations suggest that dihydrogen binds to the Ir center and generates an Ir(III)-dihydrogen complex, followed by subsequent isomerization to an Ir(V)-dihydride species. Then, a proton is abstracted by a buffer base, CH3COO-, resulting in the formation of a hydride complex. The catalytic cycle completes with electron transfer from the hydride complex to a protonated 2,6-dichlorobenzeneindophenol (DCIP) and a proton transfer from the oxidized hydride complex to a buffer base. The CO oxidation mechanism involves three distinct steps, i.e., (1) formation of a metal carbonyl complex, (2) formation of a metallocarboxylic acid, and (3) conversion of the metallocarboxylic acid to a hydride complex. The formation of the metallocarboxylic acid involves nucleophilic attack of OH- to the carbonyl-C followed by a large structural change with concomitant cleavage of the Ir-S bond and rotation of the COOH group along the NiIr axis. During the conversion of the metallocarboxylic acid to the hydride complex, intramolecular proton transfer followed by removal of CO2 leads to the formation of the hydride complexes. In addition, the barrier heights for the binding of small molecules (H2, OH-, H2O, and CO) to Ir were calculated, and the results indicated that dissociation from Ir is a faster process than the binding of H2O and H2. These calculations indicate that H2 oxidation is inhibited by CO and OH- and thus prefers acidic conditions. In contrast, the CO oxidation reactions occur more favorably under basic conditions, as the formation of the metallocarboxylic acid involves OH- attack to a carbonyl-C and the binding of OH- to Ni largely stabilizes the triplet spin state of the complex. Taken together, these calculations provide a rationale for the experimentally observed pH-dependent, selective oxidations of H2 and CO.. |
| 11. |
Ikeda, Kei; Mahyuddin, Muhammad Haris; Shiota, Yoshihito; Staykov, Aleksandar; Matsumoto, Takahiro; Ogo, Seiji; Yoshizawa, Kazunari. , Computational Study on the Light-Induced Oxidation of Iridium-Aqua Complex to Iridium-Oxo Complex over WO3(001) Surface. , Inorg. Chem. , 10.1021/acs.inorgchem.9b02704, 59, 1, 415-422, 2019.12. |
| 12. |
Kei Ikeda, Yuta Hori, Muhammad Haris Mahyuddin, Yoshihito Shiota, Aleksandar Tsekov Staykov, Takahiro Matsumoto, Kazunari Yoshizawa, Seiji Ogo, Dual Catalytic Cycle of H2 and H2O Oxidations by a Half-Sandwich Iridium Complex
A Theoretical Study, Inorganic Chemistry, 10.1021/acs.inorgchem.9b00307, 58, 11, 7274-7284, 2019.06, While hydrogenase and photosystem II enzymes are known to oxidize H2 and H2O, respectively, a recently reported iridium aqua complex [IrIII(η5-C5Me5){bpy(COOH)2}(H2O)]2+ is able to oxidize both of the molecules and generate energies as in the fuel and solar cells (Ogo et al. ChemCatChem 2017, 9, 4024-4028). To understand the mechanism behind such an interesting bifunctional catalyst, in the present study, we perform density functional theory (DFT) calculations on the dual catalytic cycle of H2 and H2O oxidations by the iridium aqua complex. In the H2 oxidation, we found that the H-H bond is easily cleaved in a heterolytic fashion, and the resultant iridium hydride complex is significantly stabilized by the presence of H2O molecules, due to dihydrogen bond. The rate-determining step of this reaction is found to be the H2O → H2 ligand substitution with an activation energy of 10.7 kcal/mol. In the H2O oxidation, an iridium oxo complex originating from an oxidation of the iridium aqua complex forms a hydroperoxide complex, where an O-O bond is formed with an activation energy of 21.0 kcal/mol. Such a relatively low activation barrier is possible only when at least two H2O molecules are present in the reaction, allowing the water nucleophilic attack (WNA) mechanism to take place. The present study suggests and discusses in detail six reaction steps required for the dual catalytic cycle to complete.. |
| 13. |
Ikeda, Kei; Hori, Yuta; Mahyuddin, Muhammad Haris; Shiota, Yoshihito; Staykov, Aleksandar; Matsumoto, Takahiro; Yoshizawa, Kazunari; Ogo, Seiji., Dual Catalytic Cycle of H2 and H2O Oxidations by a Half-Sandwich Iridium Complex: A Theoretical Study., Inorg. Chem. Inorg. Chem., 10.1021/acs.inorgchem.9b00307 , 58, 11, 7274-7284, 2019.05, 水素を酸化する酵素「ヒドロゲナーゼ」と水を酸化する酵素「光化学系II」の機能を複合した単一分子触媒を開発し、固体高分子形燃料電池の電極触媒として応用したところ、水素と水を両方燃料にできる電池の作製に成功した。均一系触媒と不均一系触媒の両方の性質を併せ持つ電極触媒の反応メカニズムの解明は極めて困難であるため、密度汎関数理論により、その反応メカニズムの詳細を明らかにした。. |
| 14. |
Takuo Minato, Takahiro Matsumoto, Seiji Ogo, Homogeneous catalytic reduction of polyoxometalate by hydrogen gas with a hydrogenase model complex, RSC Advances, 10.1039/c9ra04396a, 9, 34, 19518-19522, 2019.01, The homogeneous catalytic reduction of a polyoxometalate (POM) by hydrogen gas in aqueous media was investigated for the first time by using a [NiRu] hydrogenase model complex (I) under very mild conditions. By bubbling hydrogen gas into the buffer solution containing I and the Dawson-type POM (IIox), the color of the solution turned from pale yellow to dark blue, suggesting the reduction of IIox. The catalytic and kinetic studies revealed that I acted as an efficient catalyst to yield one-electron-reduced Dawson-type POM (IIred) with a low energy barrier for activating dihydrogen and reducing IIoxvia a hydride complex of I. The process for the one-electron reduction of IIox was confirmed by UV-vis spectroscopy, controlled potential electrolysis, and X-ray photoelectron spectroscopy. POM IIred could stably store protons and electrons and release them by addition of oxidants, demonstrating that POMs acted as redox active mediators for transporting protons and electrons from hydrogen gas to acceptors. The recycle study showed that IIox and IIred could be reduced and oxidized by hydrogen and oxygen gases, respectively, at least five times with >99% yield of reduced species, showing a durable system for extracting protons and electrons from hydrogen gas.. |
| 15. |
Yuki Mori, Tatsuya Ando, Takahiro Matsumoto, Takeshi Yatabe, Mitsuhiro Kikkawa, Ki Suk Yoon, Seiji Ogo, Multifunctional Catalysts for H2O2-Resistant Hydrogen Fuel Cells, Angewandte Chemie - International Edition, 10.1002/anie.201810270, 57, 48, 15792-15796, 2018.11, The development of hydrogen fuel cells is greatly hindered by the unwanted generation of H2O2 at the cathode. A non-Pt cathode catalyst is now shown to be capable of simultaneously reducing both O2 and H2O2, thus rendering H2O2 a useful part of the feed stream. The applicability of this unique catalyst is demonstrated by employing it in a fuel cell running on H2/CO and O2/H2O2.. |
| 16. |
Makoto Takenaka, Mitsuhiro Kikkawa, Takahiro Matsumoto, Takeshi Yatabe, Tatsuya Ando, Ki Suk Yoon, Seiji Ogo, Oxidation of Guanosine Monophosphate with O
2
via a Ru-peroxo Complex in Water, Chemistry - An Asian Journal, 10.1002/asia.201801267, 13, 21, 3180-3184, 2018.11, Oxidative damage of DNA by reactive oxygen species (ROS) is responsible for aging and cancer. Although many studies of DNA damage by ROS have been conducted, there have been no reports of the oxidation of RNA components, such as guanosine monophosphate, by metal-based species in water. Here, we report the first case of oxidation of guanosine monophosphate to 8-oxoguanosine monophosphate by a metal-based oxygen bound species, derived from O
2
and in water.. |
| 17. |
Takeshi Yatabe, Taisuke Tokunaga, Takahiro Matsumoto, Mitsuhiro Kikkawa, Ki Suk Yoon, Seiji Ogo, A MnI model for the photoinhibited species of oxygen-evolving complex, Chemistry Letters, 10.1246/cl.170869, 47, 1, 34-36, 2018.01, We report the reactivity of a new MnI(cyclam) complex (cyclam: 1,4,8,11-tetraazacyclotetradecane) toward O2 and H2O as a model for the photoinhibited species of oxygen-evolving complex (OEC). The reactivity varies according to the number of CO ligands. A MnI dicarbonyl complex, [MnI(cyclam)(CO)2]+ reacts with O2, but not with H2O, to form a bis(μ-oxo)Mn2III,IV complex, though a MnI tricarbonyl complex, [MnI(cyclam)(CO)3]+ does not react with either O2 or H2O. Newly synthesized MnI(cyclam) dicarbonyl complex was characterized by ESI mass spectrometry, UVvis absorption spectroscopy, IR spectroscopy, and X-ray analysis.. |
| 18. |
Taisuke Tokunaga, Takeshi Yatabe, Takahiro Matsumoto, Tatsuya Ando, Ki Suk Yoon, Seiji Ogo, Mechanistic investigation of the formation of H2 from HCOOH with a dinuclear Ru model complex for formate hydrogen lyase, Science and Technology of Advanced Materials, 10.1080/14686996.2017.1379857, 18, 1, 870-876, 2017.12, We report the mechanistic investigation of catalytic H2 evolution from formic acid in water using a formate-bridged dinuclear Ru complex as a formate hydrogen lyase model. The mechanistic study is based on isotope-labeling experiments involving hydrogen isotope exchange reaction.. |
| 19. |
Mitsuhiro Kikkawa, Takeshi Yatabe, Takahiro Matsumoto, Ki Suk Yoon, Kazuharu Suzuki, Takao Enomoto, Kenji Kaneko, Seiji Ogo, A Fusion of Biomimetic Fuel and Solar Cells Based on Hydrogenase, Photosystem II, and Cytochrome c Oxidase, ChemCatChem, 10.1002/cctc.201700995, 9, 21, 4024-4028, 2017.11, 本論文では、燃料電池と太陽電池を融合する同一触媒の開発について報告した。次世代の電池として、燃料電池と太陽電池はこれまで別々に開発されてきたが、本研究では、「自然界の水素酵素と光合成の機能を融合した新しい触媒」を開発に成功した。この触媒を用いることで、「水素をエネルギー源として燃料電池が、水と光をエネルギー源として太陽電池が駆動する」ことを見出した。本研究成果はエネルギー研究の分野において格段の発展と波及効果をもたらす可能性が十分に期待できる。. |
| 20. |
Takahiro Matsumoto, Takahiro Kishima, Takeshi Yatabe, Ki Suk Yoon, Seiji Ogo, Mechanistic Insight into Switching between H2- or O2-Activation by Simple Ligand Effects of [NiFe]hydrogenase Models, Organometallics, 10.1021/acs.organomet.7b00471, 36, 20, 3883-3890, 2017.10, We present a mechanistic investigation for the activation of H2 and O2, induced by a simple ligand effect within [NiFe] models for O2-tolerant [NiFe]hydrogenase. Kinetic study reveals Michaelis-Menten type saturation behaviors for both H2 and O2 activation, which is the same behavior as that found in O2-tolerant [NiFe]hydrogenase. Such saturation behavior is caused by H2 complexation followed by heterolytic cleavage of H2 by an outer-sphere base, resulting in the formation of a hydride species showing hydridic character.. |
| 21. |
Hidetaka Nakai, Masafumi Kuyama, Juncheol Seo, Takahiro Goto, Takahiro Matsumoto, Seiji Ogo, Luminescent Tb(III) and Sm(III) complexes with a 1,4,7-triazacyclononane-based tris-aryloxide ligand for high-performance oxygen sensors, Dalton Transactions, 10.1039/c7dt01388d, 46, 28, 9126-9130, 2017.06, Taking advantage of the outstanding oxygen-sensitive luminescence properties of the previously synthesised Tb(iii) complex [{(MeMeArO)3tacn}LnIII(THF)] (1Tb, Ln = Tb), herein, we have prepared an oxygen sensor based on 1Tb embedded in polystyrene film (1Tb/PS) and found that 1Tb/PS shows the highest sensitivity (I0/I100 = 14.9) and the fastest response (response/recovery time = 1.9 s/2.9 s), among the lanthanide(iii)-based oxygen sensors with f-f emission. Moreover, we have prepared the lanthanide(iii)-based colorimetric luminescent oxygen sensor (1TbSm/PS) with green-yellow-red responses, by using 1Tb and a newly synthesised oxygen-insensitive Sm(iii) complex (1Sm, Ln = Sm; Φ = 0.010 and τ = 12.2 μs).. |
| 22. |
Seiji Ogo, Yuki Mori, Tatsuya Ando, Takahiro Matsumoto, Takeshi Yatabe, Ki Suk Yoon, Hideki Hayashi, Masashi Asano, One Model, Two Enzymes
Activation of Hydrogen and Carbon Monoxide, Angewandte Chemie - International Edition, 10.1002/anie.201704864, 56, 33, 9723-9726, 2017.01, The ability to catalyze the oxidation of both H2 and CO in one reaction pot would be a major boon to hydrogen technology since CO is a consistent contaminant of H2 supplies. Here, we report just such a catalyst, with the ability to catalyze the oxidation of either or both H2 and CO, based on the pH value. This catalyst is based on a NiIr core that mimics the chemical function of [NiFe]hydrogenase in acidic media (pH 4–7) and carbon monoxide dehydrogenase in basic media (pH 7–10). We have applied this catalyst in a demonstration fuel cell using H2, CO, and H2/CO (1/1) feeds as fuels for oxidation at the anode. The power density of the fuel cell depends on the pH value in the media of the fuel cell and shows a similar pH dependence in a flask. We have isolated and characterized all intermediates in our proposed catalytic cycles.. |
| 23. |
Makoto Takenaka, Ki Seok Yoon, Takahiro Matsumoto, Seiji Ogo, Acetyl-CoA production by encapsulated pyruvate ferredoxin oxidoreductase in alginate hydrogels, Bioresource Technology, 10.1016/j.biortech.2016.12.051, 227, 279-285, 2017, Pyruvate ferredoxin oxidoreductase from Citrobacter sp. S-77 (PFORS77) was purified in order to develop a method for acetyl-CoA production. Although the purified PFORS77showed high O2-sensitivity, the activity could be remarkably stabilized in anaerobic conditions. PFORS77was effectively immobilized on ceramic hydroxyapatite (PFORS77-HA) with an efficiency of more than 96%, however, after encapsulation of PFORS77-HA in alginate, the rate of catalytic acetyl-CoA production was highly reduced to 36% when compared to that of the free enzyme. However, the operational stability of the PFORS77-HA in alginate hydrogels was remarkable, retaining over 68% initial activity even after ten repeated cycles. The results suggested that the PFORS77-HA hydrogels have a high potential for biotechnological application.. |
| 24. |
Takeshi Yatabe, Takahiro Kishima, Hideaki Nagano, Takahiro Matsumoto, Mikio Yamasaki, YOON KI SUK, Seiji Ogo, Structure and Reactivity of a Ru-based Peroxide Complex as a Reactive Intermediate of O2-Promoted Activation of a C–H Bond in a Cp* Ligand., Chem. Lett. , 10.1246/cl.160909, 46, 1, 74-76, 2016.12. |
| 25. |
Makoto Takenaka, YOON KI SUK, Takahiro Matsumoto, Seiji Ogo, Acetyl-CoA Production by Encapsulated Pyruvate Ferredoxin Oxidoreductase in Alginate Hydrogels. , Bioresour. Technol. 2017, 227, 279–285., http://doi.org/10.1016/j.biortech.2016.12.051, 227, 279-285, 2016.12. |
| 26. |
Nakai Hidetaka, Juncheol Seo, Kazuhiro Kitagawa, Takahiro Goto, Kyoshiro Nonaka, Takahiro Matsumoto, Seiji Ogo, Control of Lanthanide Coordination Environment: Synthesis, Structure, and Oxygen-Sensitive Luminescence Properties of an Eight-Coordinate Tb(III) Complex. , Inorg. Chem. , 10.1021/acs.inorgchem.6b00800, 55, 13, 6609-6615, 2016.06. |
| 27. |
Koji Yoshimoto, Takeshi Yatabe, Takahiro Matsumoto, TRAN VIET HA, ROBERTSON ANDREW, Nakai Hidetaka, Koichiro Asazawa, Hirohisa Tanaka, Seiji Ogo, Inorganic Clusters with a [Fe2MoOS3] Core—A Functional Model for Acetylene Reduction by Nitrogenases. , Dalton Trans., 10.1039/C6DT01655C, 45, 37, 14620-14627, 2016.06. |
| 28. |
Nakai Hidetaka, Juncheol Seo, Kazuhiro Kitagawa, Takahiro Goto, Takahiro Matsumoto, Seiji Ogo, An Oxygen-Sensitive Luminescent Dy(III) Complex., Dalton Trans. , 10.1039/C6DT01057A, 45, 23, 9492-9496, 2016.05. |
| 29. |
Nakai Hidetaka, Kazuhiro Kitagawa, Juncheol Seo, Takahiro Matsumoto, Seiji Ogo, A Gadolinium(III) Complex That Shows Room-Temperature Phosphorescence in the Crystalline State., Dalton Trans., 10.1039/C6DT01303A, 45, 29, 11620-11623, 2016.05. |
| 30. |
Keisuke Takashita, Takahiro Matsumoto, Takeshi Yatabe, Nakai Hidetaka, Seiji Ogo, A Non-precious Metal, Ni Molecular Catalyst for a Fuel Cell Cathode., Chem. Lett., 10.1246/cl.150988, 45, 2, 137-139, 2016.02. |
| 31. |
Koji Yoshimoto, Takeshi Yatabe, Takahiro Matsumoto, ROBERTSON ANDREW, Nakai Hidetaka, Hiromasa Tanaka, Takashi Kamachi, Yoshihito Shiota, Yoshizawa Kazunari, Koichiro Asazawa, Hirohisa Tanaka, Seiji Ogo, Synthesis and Structure of a Water-soluble μ-η1:η1-N2 Dinuclear RuII Complex with a Polyamine Ligand., Chem. Lett., 10.1246/cl.150988, 45, 2, 149-151, 2016.02. |
| 32. |
Takahiro Matsumoto, Koji Yoshimoto, Chunbai Zheng, Yasuhito Shomura, Yoshiki Higuchi, Nakai Hidetaka, Seiji Ogo, Synthesis and Reactivity of a Water-soluble NiRu Monohydride Complex with a Tethered Pyridine Moiety., Chem. Lett., 10.1246/cl.151029, 45, 2, 197-199, 2016.02. |
| 33. |
Nakai Hidetaka, Kengo Matsuba, Masataka Akimoto, Tomonori Nozaki, Takahiro Matsumoto, Kiyoshi Isobe, Masahiro Irie, Seiji Ogo, Photoinduced Bending of Rod-like Millimetre-size Crystals of a Rhodium Dithionite Complex with n-Pentyl Moieties., Chem. Commun., 10.1039/C6CC00059B , 52, 23, 4349-4352, 2016.02. |
| 34. |
Keisuke Takashita, Takahiro Matsumoto, Takeshi Yatabe, Nakai Hidetaka, Masatatsu Suzuki, Seiji Ogo, A Water-soluble Ni Dihydrido Complex That Reduces O2 to H2O in Water., Chem. Lett., 10.1246/cl.150935, 45, 1, 72-74, 2016.01. |
| 35. |
Takahiro Kishima, Takahiro Matsumoto, Hidetaka Nakai, Shinya Hayami, Takehiro Ohta, Seiji Ogo, A High-Valent Iron(IV) Peroxo Core Derived from O2, Angewandte Chemie - International Edition, 10.1002/anie.201507022, 55, 2, 724-727, 2016.01, Dioxygen-tolerant [NiFe] hydrogenases catalyze not only the conversion of H2 into 2 H+ and 2 e- but also the reduction of O2 to H2O. Chemists have sought to mimic such bifunctional catalysts with structurally simpler compounds to facilitate analysis and improvement. Herein, we report a new [NiFe]-based catalyst for O2 reduction via an O2 adduct. Structural investigations reveal the first example of a side-on iron(IV) peroxo complex. Dioxygen-tolerant [NiFe] hydrogenases catalyze not only the conversion of H2 into 2 H+ and 2 e- but also the reduction of O2 to H2O. A new [NiFe]-based complex is a synthetic mimic of such hydrogenases and catalyzes O2 reduction via an O2 adduct, which was shown to be the first example of a side-on iron(IV) peroxo complex.. |
| 36. |
Hidetaka Nakai, Kazuhiro Kitagawa, Juncheol Seo, Takahiro Matsumoto, Seiji Ogo, A gadolinium(III) complex that shows room-temperature phosphorescence in the crystalline state, Dalton Transactions, 10.1039/c6dt01303a, 45, 29, 11620-11623, 2016.01, This paper presents a gadolinium(iii) complex that shows blue phosphorescence in the crystalline state at room temperature under air atmosphere; color of the crystals can be changed to pale-green from blue by doping of 1-naphthol.. |
| 37. |
Koji Yoshimoto, Takeshi Yatabe, Takahiro Matsumoto, Viet Ha Tran, Andrew Robertson, Hidetaka Nakai, Koichiro Asazawa, Hirohisa Tanaka, Seiji Ogo, Inorganic clusters with a [Fe2MoOS3] core - A functional model for acetylene reduction by nitrogenases, Dalton Transactions, 10.1039/c6dt01655c, 45, 37, 14620-14627, 2016.01, We report the first example of a wholly inorganic mimic of a part of the FeMoco active centre of nitrogenases. We detail the synthesis, characterisation and reactivity of two related, transient hydride-containing inorganic clusters, a dihydride complex and a vinyl monohydride complex, which bear the [Fe2MoOS3] portion of FeMoco. The dihydride complex is capable of reducing acetylene to ethylene via the vinyl monohydride complex. In the reaction cycle, a transient low-valent complex was generated by the reductive elimination of H2 or ethylene from dihydride or vinyl monohydride complexes, respectively.. |
| 38. |
Koji Yoshimoto, Takeshi Yatabe, Takahiro Matsumoto, Andrew Robertson, Hidetaka Nakai, Hiromasa Tanaka, Takashi Kamachi, Yoshihito Shiota, Kazunari Yoshizawa, Koichiro Asazawa, Hirohisa Tanaka, Seiji Ogo, Synthesis and structure of a water-soluble μ-η1
η1-N2 dinuclear RuII complex with a polyamine ligand, Chemistry Letters, 10.1246/cl.151004, 45, 2, 149-151, 2016.01, We report the first example of a μ-η1:η1-N2 dinuclear RuII complex with a polyamine ligand and elucidate the structure by means of X-ray analysis. The N=N stretching vibration has been observed at 1994 cm-1 by Raman spectroscopy, which is the lowest value of all the known N2-coordinated RuII complexes. This low value strongly suggests the N=N bond is primed for activation.. |
| 39. |
Hidetaka Nakai, Juncheol Seo, Kazuhiro Kitagawa, Takahiro Goto, Takahiro Matsumoto, Seiji Ogo, An oxygen-sensitive luminescent Dy(III) complex, Dalton Transactions, 10.1039/c6dt01057a, 45, 23, 9492-9496, 2016, This paper presents the first dysprosium(iii) complex, [{(MeMeArO)3tacn}DyIII(THF)] (1Dy), that shows oxygen-sensitive luminescence. The synthesis, structure and oxygen-sensitive luminescence properties of 1Dy are reported (Φ = 0.050 and τ = 17.7 μs under N2, Φ = 0.011 and τ = 4.1 μs under O2 and KSV = 305 M-1 in THF; KSV = 0.0077%-1 in polystyrene film). The oxygen sensitive mechanism of 1Dy is discussed based on the photophysical properties of the corresponding gadolinium(iii) complex, [{(MeMeArO)3tacn}GdIII(THF)].. |
| 40. |
Hidetaka Nakai, Kengo Matsuba, Masataka Akimoto, Tomonori Nozaki, Takahiro Matsumoto, Kiyoshi Isobe, Masahiro Irie, Seiji Ogo, Photoinduced bending of rod-like millimetre-size crystals of a rhodium dithionite complex with n-pentyl moieties, Chemical Communications, 10.1039/c6cc00059b, 52, 23, 4349-4352, 2016, Rod-like millimetre-size crystals of a newly prepared rhodium dithionite complex with n-pentyl moieties bend upon photoirradiation and return to the initial shape upon heating; the roles of the flexible n-pentyl moieties as well as the photoreactive dithionite unit (μ-O2SSO2) are disclosed by single crystal X-ray diffraction.. |
| 41. |
Takahiro Matsumoto, Tatsuya Ando, Yuki Mori, Takeshi Yatabe, Hidetaka Nakai, Seiji Ogo, A (Ni-SIr)I model for [NiFe]hydrogenase, Journal of Organometallic Chemistry, 10.1016/j.jorganchem.2014.09.025, 796, 73-76, 2015.11, We report the synthesis and characterization of a μ-hydroxo NiRu complex as a model for the active site of (Ni-SIr)I of [NiFe]hydrogenase. This is the first example of the (Ni-SIr)I model with a bridging hydroxo ligand between dimetal centers and an available coordination site on Ni center cis to the bridging hydroxo ligand. We have determined the structure of the (Ni-SIr)I model complex by X-ray analysis and reported reversible switching between the catalytically inactive (Ni-SIr)I and a catalytically active (Ni-SIr)II models.. |
| 42. |
Takahiro Kishima, Takahiro Matsumoto, Nakai Hidetaka, Shinya Hayami, Takehiro Ohta, Seiji Ogo, A High-Valent Iron(IV) Peroxo Core Derived from O2. Angew. Chem. Int. Ed., Angew. Chem. Int. Ed., 10.1002/anie.201507022. , 55, 2, 724-727, 2015.10. |
| 43. |
Viet Ha Tran, Takeshi Yatabe, Takahiro Matsumoto, Hidetaka Nakai, Kazuharu Suzuki, Takao Enomoto, Takashi Hibino, Kenji Kaneko, Seiji Ogo, An IrSi oxide film as a highly active water-oxidation catalyst in acidic media, Chemical Communications, 10.1039/c5cc04286k, 51, 63, 12589-12592, 2015.08, We report an acid-stable Si oxide-doped Ir oxide film (IrSi oxide film), made by metal organic chemical vapour deposition (MOCVD) of an IrV complex for electrochemical water-oxidation. This is a successful improvement of catalytic ability and stability depending upon the pH of Ir oxide by doping of Si oxide. The turnover frequency (TOF) of the electrochemical water-oxidation by the IrSi oxide film is the highest of any Si oxide-doped Ir oxide materials and higher even than that of Ir oxide in acidic media.. |
| 44. |
Viet-Ha Tran, Takeshi Yatabe, Takahiro Matsumoto, Nakai Hidetaka, Kazuharu Suzuki, Takao Enomoto, Takashi Hibino, Kenji Kaneko, Seiji Ogo, An IrSi Oxide Film as a Highly Active Water-Oxidation Catalyst in Acidic Media. , Chem. Commun. , 10.1039/C5CC04286K, 51, 63, 12589-12592, 2015.07. |
| 45. |
Viet-Ha Tran, Takeshi Yatabe, Takahiro Matsumoto, Nakai Hidetaka, Kazuharu Suzuki, Takao Enomoto, Seiji Ogo, An N2-Compatible Ni0 MOCVD precursor. , Chem. Lett. , org/10.1246/cl.150155, 44, 6, 794-796, 2015.06. |
| 46. |
Hidetaka Nakai, Kyoshiro Nonaka, Takahiro Goto, Juncheol Seo, Takahiro Matsumoto, Seiji Ogo, A macrocyclic tetraamine bearing four phenol groups
a new class of heptadentate ligands to provide an oxygen-sensitive luminescent Tb(iii) complex with an extendable phenol pendant arm, Dalton Transactions, 10.1039/c5dt00816f, 44, 24, 10923-10927, 2015.06, This paper presents a 1,4,7,10-teraazacyclododecane-based tetrakis-phenol as a protonated ligand precursor and its oxygen-sensitive luminescent terbium(iii) complex with an extendable phenol pendant arm (Φ = 0.91 under N2, Φ = 0.031 under air), in which the potentially N4O4-octadentate ligand unprecedentedly coordinates to the Tb3+ ion in a N4O3-heptadentate fashion.. |
| 47. |
Nakai Hidetaka, Kyoshiro Nonaka, Juncheol Seo, Takahiro Matsumoto, Seiji Ogo, A Macrocyclic Tetraamine bearing Four Phenol Groups: A New Class of Heptadentate Ligands To Provide an Oxygen-Sensitive Luminescent Tb(III) Complex with an Extendable Phenol Pendant Arm. , Dalton Trans. , 10.1039/C4CC07717B, 44, 24, 10923-10927, 2015.05. |
| 48. |
Takeshi Yatabe, Mitsuhiro Kikkawa, Takahiro Matsumoto, Keishi Urabe, ROBERTSON ANDREW, Nakai Hidetaka, Seiji Ogo, An Fe-based Model for Metabolism Linking between O2-reduction and H2O-oxidation. , Chem. Lett. , org/10.1246/cl.150468, 44, 9, 1263-1265, 2015.05. |
| 49. |
Viet Ha Tran, Takeshi Yatabe, Takahiro Matsumoto, Hidetaka Nakai, Kazuharu Suzuki, Takao Enomoto, Seiji Ogo, An N2-compatible Ni0 metal-organic chemical vapor deposition (MOCVD) precursor, Chemistry Letters, 10.1246/cl.150155, 44, 6, 794-796, 2015.01, We report the first example of a Ni0 precursor that provides a contamination-free (2 as the carrier gas. The structure and physical properties of the Ni0 precursor and subsequent film are described.. |
| 50. |
Takeshi Yatabe, Mitsuhiro Kikkawa, Takahiro Matsumoto, Keishi Urabe, Andrew Robertson, Hidetaka Nakai, Seiji Ogo, An fe-based model for metabolism linking between O2-reduction and H2O-oxidation, Chemistry Letters, 10.1246/cl.150468, 44, 9, 1263-1265, 2015.01, Here, we report the first Fe-based model for metabolism linking between the dioxygen reduction of respiration and the water oxidation of photosynthesis. The reaction mechanism was investigated by X-ray analysis, UV-vis spectroscopy, and mass spectrometry.. |
| 51. |
Nga T. Nguyen, Yuki Mori, Takahiro Matsumoto, Takeshi Yatabe, Ryota Kabe, Hidetaka Nakai, Ki Seok Yoon, Seiji Ogo, A [NiFe]hydrogenase model that catalyses the release of hydrogen from formic acid, Chemical Communications, 10.1039/c4cc05911e, 50, 87, 13385-13387, 2014.11, We report the decomposition of formic acid to hydrogen and carbon dioxide, catalysed by a NiRu complex originally developed as a [NiFe]hydrogenase model. This is the first example of H2 evolution, catalysed by a [NiFe]hydrogenase model, which does not require additional energy.. |
| 52. |
Hidetaka Nakai, Takahiro Goto, Kazuhiro Kitagawa, Kyoshiro Nonaka, Takahiro Matsumoto, Seiji Ogo, A highly luminescent and highly oxygen-sensitive Tb(III) complex with a tris-aryloxide functionalised 1,4,7-triazacyclononane ligand, Chemical Communications, 10.1039/c4cc07717b, 50, 99, 15737-15739, 2014.11, This communication presents a new terbium(III) complex that shows the highest luminescence quantum yield among the oxygen-sensitive lanthanide complexes (Φ = 0.91 under N2, Φ = 0.054 under air).. |
| 53. |
Nakai Hidetaka, Takahiro Goto, Kazuhiro Kitagawa, Kyoshiro Nonaka, Takahiro Matsumoto, Seiji Ogo, A Highly Luminescent and Highly Oxygen-Sensitive Tb(III) Complex with a Tris-Aryloxide Functionalised 1,4,7-Triazacyclononane Ligand. , Chem. Commun. , 10.1039/C4CC07717B, 50 , 99, 15737-15739, 2014.10. |
| 54. |
Harutaka Nakamori, Takahiro Matsumoto, Takeshi Yatabe, Ki Seok Yoon, Hidetaka Nakai, Seiji Ogo, Synthesis and crystal structure of a dinuclear, monomeric MnIIp-semiquinonato complex, Chemical Communications, 10.1039/c4cc06055e, 50, 86, 13059-13061, 2014.10, Herein, we report the first crystal structure of a monomeric p-semiquinonato d-block complex and its reactivity toward dioxygen, closely associated with a biological system of an oxygen evolving centre of photosystem II.. |
| 55. |
Harutaka Nakamori, Takahiro Matsumoto, Takeshi Yatabe, Yoon Ki-Seok, Nakai Hidetaka, Seiji Ogo, Synthesis and Crystal Structure of a Dinuclear, Monomeric MnII p-Semiquinonato Complex. , Chem. Commun. , 50, 86, 13059-13061, 2014.09. |
| 56. |
Nguyen, Nga T., Yuki Mori, Takahiro Matsumoto, Takeshi Yatabe, Ryota Kabe, Nakai Hidetaka, Yoon Ki-Seok, Seiji Ogo, A [NiFe]hydrogenase Model That Catalyses the Release of Hydrogen from Formic Acid. , Chem. Commun. , 50, 87, 13385-13387, 2014.09. |
| 57. |
Takahiro Matsumoto, Tatsuya Ando, Yuki Mori, Takeshi Yatabe, Nakai Hidetaka, Seiji Ogo, A (Ni-SIr)I Model for [NiFe]hydrogenase. , J. Organomet. Chem., 2014.09. |
| 58. |
Hidetaka Nakai, Kihun Jeong, Takahiro Matsumoto, Seiji Ogo, Catalytic C-F bond hydrogenolysis of fluoroaromatics by [(η5-C5Me5)RhI(2,2′-bipyridine)], Organometallics, 10.1021/om500647h, 33, 17, 4349-4352, 2014.09, A new class of efficient catalyst, the Rh(I) complex [(η5-C5Me5)RhI(bpy)] (1; bpy = 2,2′-bipyridine), for the C-F bond hydrogenolysis of fluoroaromatics (C6F5CF3, C6F6, C6F5H, and C6F5CH3) is presented. The best turnover number of 380 for C6F6 is afforded by using 0.1 mol % of 1, 0.8 MPa of H2, and 2 equiv of Et2NH in CH3CN at 25 °C. The successful isolation of the C-F bond cleavage product [(η5-C5Me5)RhIII(bpy)(C6F5)](F) as a plausible intermediate of the catalytic hydrogenolysis of C6F6 by 1 is also described.. |
| 59. |
Takeshi Yatabe, Takahiro Kikunaga, Takahiro Matsumoto, Nakai Hidetaka, Yoon Ki-Seok, Seiji Ogo, Synthesis of Aqueous-stable and Water-soluble Mononuclear Nonheme MnV–oxo Complexes Using H2O2 as an Oxidant. , Chem. Lett., 43, 8, 1380-1382, 2014.08. |
| 60. |
Nakai Hidetaka, Kihun Jeong, Takahiro Matsumoto, Seiji Ogo, Catalytic C−F Bond Hydrogenolysis of Fluoroaromatics by [(η5‑C5Me5)RhI(2,2′-bipyridine)]., Organometallics , 33, 17, 4349-4352, 2014.08. |
| 61. |
Takahiro Matsumoto, Shigenobu Eguchi, Hidetaka Nakai, Takashi Hibino, Ki Suk Yoon, Seiji Ogo, Hydrogenase from citrobacter sp. S-77 surpasses platinum as an electrode for H2 oxidation reaction, Angewandte Chemie - International Edition, 10.1002/anie.201404701, 53, 34, 8895-8898, 2014.08, Reported herein is an electrode for dihydrogen (H2) oxidation, and it is based on [NiFe]Hydrogenase from Citrobacter sp. S-77 ([NiFe] S77). It has a 637 times higher mass activity than Pt (calculated based on 1 mg of [NiFe]S77 or Pt) at 50 mV in a hydrogen half-cell. The [NiFe]S77 electrode is also stable in air and, unlike Pt, can be recovered 100% after poisoning by carbon monoxide. Following characterization of the [NiFe]S77 electrode, a fuel cell comprising a [NiFe] S77 anode and Pt cathode was constructed and shown to have a a higher power density than that achievable by Pt.. |
| 62. |
Takahiro Matsumoto, Shigenobu Eguchi, Nakai Hidetaka, Takashi Hibino, Yoon Ki-Seok, Seiji Ogo, [NiFe]Hydrogenase from Citrobacter sp. S-77 Surpasses Platinum as an Electrode for H2 Oxidation Reaction. , Angew. Chem. Int. Ed. , 53, 34, 8895-8898, 2014.06, 水素と酸素から電気を作る燃料電池は、排出物として水しか生成しないクリーンな発電装置である。燃料電池はその構造によって数種類に分類され、なかでも低温作動や小型軽量化が可能な固体高分子形燃料電池（polymer electrolyte fuel cell、PEFC）は、家庭用、携帯用、自動車用電源に適している。しかし、PEFCの電極触媒は枯渇資源で高価な白金触媒であり、その代替触媒の開発が行われてきたが、未だに白金に代わる実用触媒の開発には至っていない。本研究では、水素極（水素から電子を取り出す電極）の脱白金触媒として水素酸化酵素であるヒドロゲナーゼを用いたPEFCを初めて作製し、それらの発電実験に成功した。本研究で使用したヒドロゲナーゼS–77（当研究室で新規に探索・精製・単離）は、これまでのヒドロゲナーゼよりも高活性かつ頑丈であり、PEFCの作動条件でも十分にその機能を発揮できる。ヒドロゲナーゼS–77の単位重量あたりの水素酸化活性は、白金触媒に対して637倍であることを明らかにした。. |
| 63. |
Takeshi Yatabe, Mitsuhiro Kikkawa, Takahiro Matsumoto, Nakai Hidetaka, Kenji Kaneko, Seiji Ogo, A Model for the Water-Oxidation and Recovery Systems of the Oxygen-Evolving Complex., Dalton Trans. , 43, 8, 3063–3071, 2014.02. |
| 64. |
Takeshi Yatabe, Mitsuhiro Kikkawa, Takahiro Matsumoto, Hidetaka Nakai, Kenji Kaneko, Seiji Ogo, A model for the water-oxidation and recovery systems of the oxygen-evolving complex, Dalton Transactions, 10.1039/c3dt52846d, 43, 8, 3063-3071, 2014.02, We propose a model for the water-oxidation and recovery systems of the oxygen-evolving complex (OEC) of the photosystem II (PSII) enzyme. The whole system is constructed from two catalytic cycles, conducted as a tandem reaction: (i) a water-oxidation loop uses cerium(iv) ammonium nitrate as an oxidant to activate a dimanganese complex for water-oxidation and thereby liberate a molecule of O2 and (ii) a recovery loop begins with photoinhibition of the dimanganese complex but then uses O2 to reactivate the manganese centre. The net result is a catalytic water-oxidation catalyst that can use self-generated O2 for recovery.. |
| 65. |
Takeshi Yatabe, Takahiro Kikunaga, Takahiro Matsumoto, Hidetaka Nakai, Ki Seok Yoon, Seiji Ogo, Synthesis of aqueous-stable and water-soluble mononuclear nonheme MnV-Oxo complexes using H2O2as an oxidant, Chemistry Letters, 10.1246/cl.140376, 43, 8, 1380-1382, 2014.01, We report the synthesis of mononuclear nonheme manganese(V)oxo complexes in aqueous acetonitrile solution from the reaction of manganese(III) complexes using hydrogen peroxide as an oxidant for the first time. A crystal structure of chloro derivative of manganese(V)oxo complex and its reactivity toward 3,5-di-tert-butyl-catechol are also reported.. |
| 66. |
Takahiro Kikunaga, Takahiro Matsumoto, Takehiro Ohta, Nakai Hidetaka, Yoshinari Naruta, Kwang-Hyun Ahn, Yoshihito Watanabe, Seiji Ogo, Isolation of a MnIV Acylperoxo Complex and Its Monooxidation Ability. , Chem. Commun. , 49, 75, 8356-8358, 2013.10. |
| 67. |
Daisuke Inoki, Takahiro Matsumoto, Hidetaka Nakai, Seiji Ogo, Isolation and crystal structure of the proposed low-valent active species in the H2 activation catalytic cycle, European Journal of Inorganic Chemistry, 10.1002/ejic.201300049, 22-23, 3978-3986, 2013.10, We provide confirmation of our proposed design principles for a H 2 activation catalytic cycle by constructing a new catalyst. We have been able to obtain a crystal structure to confirm our proposition that a reduced, dinuclear species stores electrons from hydrogen molecules in a metal-metal bond.. |
| 68. |
Daisuke Inoki, Takahiro Matsumoto, Nakai Hidetaka, Seiji Ogo, Isolation and Crystal Structure of the Proposed Low-Valent Active Species in the H2 Activation Catalytic Cycle., Eur. J. Inorg. Chem. , 2013(22-23), 22-23, 3978-3986, 2013.08. |
| 69. |
Nakai Hidetaka, Kazuhiro Kitagawa, Harutaka Nakamori, Taisuke Tokunaga, Takahiro Matsumoto, Koichi Nozaki, Seiji Ogo, Reversible Switching of the Luminescence of a Photoresponsive Gadolinium(III) Complex. , Angew. Chem. Int. Ed., 52, 33, 8722-8725, 2013.08. |
| 70. |
Takahiro Kikunaga, Takahiro Matsumoto, Takehiro Ohta, Hidetaka Nakai, Yoshinori Naruta, Kwang Hyun Ahn, Yoshihito Watanabe, Seiji Ogo, Isolation of a MnIV acylperoxo complex and its monooxidation ability, Chemical Communications, 10.1039/c3cc43447h, 49, 75, 8356-8358, 2013.08, The first example of monooxygenation by a high-valent MnIV complex with a peroxide is described. A key MnIV acylperoxo intermediate, which uses m-chloroperoxybenzoic acid as the oxygen donor, is directly observed by electro-spray ionization mass spectrometry and resonance Raman spectroscopy.. |
| 71. |
Hidetaka Nakai, Kazuhiro Kitagawa, Harutaka Nakamori, Taisuke Tokunaga, Takahiro Matsumoto, Koichi Nozaki, Seiji Ogo, Reversible switching of the luminescence of a photoresponsive gadolinium(III) complex, Angewandte Chemie - International Edition, 10.1002/anie.201303137, 52, 33, 8722-8725, 2013.08, From blue to red: The structure and luminescence properties of the gadolinium(III) complex 1 were investigated. Reversible switching of the luminescence of 1 in THF at room temperature by alternating light irradiation and O2 exposure is presented, during which the emission color changes as shown in the picture. Light-induced phosphorescence of 1 plays a key role in this behavior.. |
| 72. |
Takahiro Matsumoto, Kyoungmok Kim, Nakai Hidetaka, Takashi Hibino, Seiji Ogo, Organometallic Catalysts for Use in a Fuel Cell. , ChemCatChem, 5, 6, 1368-1373, 2013.06. |
| 73. |
Takahiro Matsumoto, Kyoungmok Kim, Hidetaka Nakai, Takashi Hibino, Seiji Ogo, Organometallic Catalysts for Use in a Fuel Cell, ChemCatChem, 10.1002/cctc.201200595, 5, 6, 1368-1373, 2013.06, We report the successful increase in performance of a fuel cell based on organometallic catalysis. An organometallic [NiIIRuIV] peroxo complex functions as cathode catalyst and was designed following mechanistic consideration of the cell. It was confirmed that the organometallic [NiIIRuIV] peroxo catalyst could function in the fuel cell with a 240% increase in power output over our previous systems. This organometallic catalyst can act in both solid and solution phases and allows observation of the mechanism, hence providing us further opportunity for future improvement.. |
| 74. |
Seiji Ogo, Koji Ichikawa, Takahiro Kishima, Takahiro Matsumoto, Nakai Hidetaka, Katsuhiro Kusaka, Takashi Ohhara, A Functional [NiFe]Hydrogenase Mimic That Catalyzes Electron and Hydride Transfer from H2. , Science , 339, 6120, 682-684, 2013.02, ニッケル・鉄ヒドロゲナーゼは、常温・常圧という温和な条件下で触媒的に水素を酸化する酵素である。多くの研究グループが、ニッケル・鉄ヒドロゲナーゼの機能モデル錯体の開発を試みてきたが、これまで達成されることはなかった。本研究では、世界で初めて常温・常圧で水素をヘテロリティックに活性化し、水素を酸化できるニッケル・鉄モデル錯体の開発に成功した。その反応中間体であるヒドリド錯体の構造は、X線構造解析をはじめとする種々の分光学的測定によって決定された。. |
| 75. |
Seiji Ogo, Koji Ichikawa, Takahiro Kishima, Takahiro Matsumoto, Hidetaka Nakai, Katsuhiro Kusaka, Takashi Ohhara, A functional [NiFe]hydrogenase mimic that catalyzes electron and hydride transfer from H2, Science, 10.1126/science.1231345, 339, 6120, 682-684, 2013.02, Chemists have long sought to mimic enzymatic hydrogen activation with structurally simpler compounds. Here, we report a functional [NiFe]-based model of [NiFe]hydrogenase enzymes. This complex heterolytically activates hydrogen to form a hydride complex that is capable of reducing substrates by either hydride ion or electron transfer. Structural investigations were performed by a range of techniques, including x-ray diffraction and neutron scattering, resulting in crystal structures and the finding that the hydrido ligand is predominantly associated with the Fe center. The ligand's hydridic character is manifested in its reactivity with strong acid to liberate H2.. |
| 76. |
Kyoungmok Kim, Takahiro Kishima, Takahiro Matsumoto, Hidetaka Nakai, Seiji Ogo, Selective redox activation of H2 or O2 in a [NiRu] complex by aromatic ligand effects, Organometallics, 10.1021/om300833m, 32, 1, 79-87, 2013.01, We present two closely related series of a [NiFe] hydrogenase analogue. Based on a [NiRu] core, these complexes demonstrate inactivity, H2 activation, or O2 activation depending only on the nature of the Ru-coordinated aromatic ligand. It is demonstrated that even small changes made to this aromatic ligand can modulate the catalytic activity of the complex. Structural, electrochemical, kinetic, and thermodynamic studies reveal that differences in activation and binding modes of the substrates, combined with differences in σ donation and lability of the aromatic ligands, result in abrupt changes in catalytic activity.. |
| 77. |
Kyoungmok Kim, Takahiro Kishima, Takahiro Matsumoto, Nakai Hidetaka, Seiji Ogo, Selective Redox Activation of H2 or O2 in a [NiRu] Complex by Aromatic Ligand Effects. , Organometallics, 32, 1, 79-87, 2012.12. |
| 78. |
Jeong, Kihun; Nakamori, Harutaka; Imai, Shunsuke; Matsumoto, Takahiro; Ogo, Seiji;*Nakai, Hidetaka.*, A Neutral Five-coordinated Organoruthenium(0) Complex:X-ray Structure and Unique Solvatochromism., Chem. Lett., 41, 6, 650-651, 2012.06. |
| 79. |
Kihun Jeong, Harutaka Nakamori, Shunsuke Imai, Takahiro Matsumoto, Seiji Ogo, Hidetaka Nakai, A neutral five-coordinated organoruthenium(0) complex
X-ray structure and unique solvatochromism, Chemistry Letters, 10.1246/cl.2012.650, 41, 6, 650-651, 2012.06, The structure of a neutral five-coordinated organoruthenium( 0) complex [(η 6-C 6Me 6)Ru 0(bpy)] (1, bpy: 2,2′-bipyridine) was determined by X-ray diffraction analysis. The solvent-induced reversible color change based on the interconversion between the purple Ru 0 complex 1 and a yellow Ru IIhydride complex [(η 6-C 6Me 6)Ru II(bpy)H] + is presented.. |
| 80. |
Kyoungmok Kim, Takahiro Matsumoto, Andrew Robertson, Hidetaka Nakai, Seiji Ogo, Simple ligand effects switch a hydrogenase mimic between H 2 and O 2 activation, Chemistry - An Asian Journal, 10.1002/asia.201101020, 7, 6, 1394-1400, 2012.06, Herein, we report a [NiRu] biomimetic system for O 2-tolerant [NiFe]hydrogenases and demonstrate that electron donation to the [NiRu] center can switch the system between the activation of H 2 and O 2 through simple ligand effects by using hexamethylbenzene and pentamethylcyclopentadienyl ligands, respectively. Furthermore, we present the synthesis and direct observations of a [NiRu]-peroxo species, which was formed by the oxygenation of a Ni-SIa model [NiRu] complex, that we propose as a biomimetic analogue of O 2-bound species (OBS) of O 2-tolerant [NiFe]hydrogenases. The [NiRu]-peroxo complex was fully characterized by X-ray analysis, X-ray photoelectron spectroscopy (XPS), mass spectrometry, and 1H NMR spectroscopy. The OBS analogue was capable of oxidizing p-hydroquinone and sodium borohydride to turn back into the Ni-SIa model complex.. |
| 81. |
Daisuke Inoki, Takahiro Matsumoto, Hideki Hayashi, Keisuke Takashita, Hidetaka Nakai, Seiji Ogo, Establishing the mechanism of Rh-catalysed activation of O 2 by H 2, Dalton Transactions, 10.1039/c1dt11599e, 41, 15, 4328-4334, 2012.04, Reductive activation of O 2 by H 2 with rhodium terpyridine complexes in H 2O and CH 3CN is described and the mechanism is fully elucidated. The rhodium complex extracts electrons from H 2 and reductively activates O 2 to form a peroxo active intermediate. This intermediate is able to oxidise triphenyl phosphine to triphenyl phosphine oxide. A model system constructed in CH 3CN provides isolable analogues of catalytic intermediates in H 2O, allowing a detailed look at each step in the catalytic cycle.. |
| 82. |
Daisuke Inoki, Takahiro Matsumoto, Hidetaka Nakai, Seiji Ogo, Experimental study of reductive elimination of H 2 from rhodium hydride species, Organometallics, 10.1021/om2009759, 31, 8, 2996-3001, 2012.04, A Rh III monohydride terpyridine complex undergoes reductive elimination of H 2 in CH 3CN to form a dinuclear Rh II complex with a metal-metal bond. Kinetic studies have revealed that the conversion from the monohydride species to the dinuclear species with evolution of H 2 obeys first-order kinetics and have determined the kinetic deuterium isotope effect value to be 2.0. We discuss the mechanism for the reductive elimination of H 2 from rhodium hydride species.. |
| 83. |
Inoki, Daisuke; Matsumoto, Takahiro; Nakai, Hidetaka; Ogo, Seiji, Experimental Study of Reductive Elimination of H2 from Rhodium Hydride Species, Organometallics, 31, 8, 2996-3001, 2012.03. |
| 84. |
Kim, Kyoungmok; Matsumoto, Takahiro; Robertson, Andrew; Nakai, Hidetaka; Ogo, Seiji, Simple Ligand Effects Switch a Hydrogenase Mimic between H2 and O2 Activation, Chem. Asian J., 2012.02. |
| 85. |
Daisuke Inoki, Takahiro Matsumoto, Hidetaka Nakai, Seiji Ogo, A mer-Triaqua Rh complex with a terpyridine ligand, Chemistry Letters, 10.1246/cl.2012.116, 41, 1, 116-118, 2012.01, We report the synthesis of a mer-triaqua Rh III complex using terpyridine as a meridional tridentate ligand. This is the first example of a structurally characterized six-coordinated mertriaqua complex for any second- or third-row element from the main transition-metal groups (groups 511). This is also the first example of a structurally characterized mer-triaqua complex with terpyridine for any transition metal. Acid dissociation constants, pK a1 and pK a2, of the triaqua complex are determined to be 3.0 and 6.9, respectively.. |
| 86. |
Inoki, Daisuke; Matsumoto, Takahiro; Nakai, Hidetaka; Ogo, Seiji, A mer-Triaqua Rh Complex with a Terpyridine Ligand, Chem. Lett., 41, 1, 116-118, 2011.12. |
| 87. |
Inoki, Daisuke; Matsumoto, Takahiro; Hayashii, Hideki; Takashita, Keisuke; Nakai, Hidetaka; Ogo, Seiji, Establishing the Mechanism of Rh-catalysed Activation of O2 by H2, Dalton Transactions, DOI: 10.1039/c1dt11599e, 2011.11. |
| 88. |
Robertson, Andrew; Matsumoto, Takahiro; Ogo, Seiji, The Development of Aqueous Transfer Hydrogenation Catalysts, Dalton Transactions, 40, 10304-10310, 2011.10. |
| 89. |
Tatsuya Ando, Naoki Nakata, Kazuharu Suzuki, Takahiro Matsumotoa, and Seiji Ogo, Ru Ccyclooctatetraene Precursors for MOCVD, Dalton Trans., 10.1039/c1dt11454a, 2011.10. |
| 90. |
Andrew Robertson, Takahiro Matsumoto, Seiji Ogo, The development of aqueous transfer hydrogenation catalysts, Dalton Transactions, 10.1039/c1dt10544b, 40, 40, 10304-10310, 2011.10, This review discusses the development of aqueous phase, homogeneous, transfer hydrogenation catalysis. Transfer hydrogenation catalysts, based on Ru, Ir and Rh, reduce organic substrates in water by assisting the transfer of hydrogen from simple donor species. These catalysts are expected to have significant benefits when compared with organic phase catalysts, including greater activity, greater selectivity and smaller environmental impact. They will therefore be expected to make a significant contribution to homogeneous catalysis and 'green chemistry'. Here, we comprehensively examine these catalysts, paying special attention to structural features.. |
| 91. |
Matsumoto, Takahiro; Kim, Kyoungmok; Ogo, Seiji, Molecular Catalysis in a Fuel Cell, Angew. Chem., Int. Ed., 10.1002/anie.201104498, 50, 47, 11202-11205, 2011.09, 一般的に燃料電池電極触媒には、枯渇資源で高価な白金触媒が使用されているため、その代替触媒の開発が実用化に向けて不可欠である。本論文では、白金の代替となる分子触媒を開発し、世界で初めて分子触媒を用いた燃料電池、分子燃料電池、の開発に成功した。. |
| 92. |
Takahiro Matsumoto, Takuma Nagahama, Jaeheung Cho, Takuhiro Hizume, Masatatsu Suzuki, and Seiji Ogo, Preparation and Reactivity of a Nickel Dihydride Complex, Angew. Chem. Int. Ed., 10.1002/anie.201104918, 50, 45, 10578-10560, 2011.09, 水素酸化酵素であるヒドロゲナーゼは、温和な条件下（水中・常温・常圧）で、水素の酸化を触媒する魅力的な酵素である。その酵素１分子単位での水素酸化の触媒効率は、人工触媒である白金よりも優れているため、ヒドロゲナーゼの反応メカニズムの解明は非常に重要である。しかし、その反応メカニズムの鍵となる活性中間体であるジヒドリド錯体は、これまで観測されていなかった。本研究では世界で初めてその活性中間体のモデル錯体の合成・同定に成功した。. |
| 93. |
Takahiro Matsumoto, Ryota Kabe, Kyoshiro Nonaka, Tatsuya Ando, Ki Suk Yoon, Hidetaka Nakai, Seiji Ogo, Model study of CO inhibition of [NiFe]hydrogenase, Inorganic Chemistry, 10.1021/ic200965t, 50, 18, 8902-8906, 2011.09, We propose a modified mechanism for the inhibition of [NiFe]hydrogenase ([NiFe]H 2ase) by CO. We present a model study, using a NiRu H 2ase mimic, that demonstrates that (i) CO completely inhibits the catalytic cycle of the model compound, (ii) CO prefers to coordinate to the Ru II center rather than taking an axial position on the Ni II center, and (iii) CO is unable to displace a hydrido ligand from the NiRu center. We combine these studies with a reevaluation of previous studies to propose that, under normal circumstances, CO inhibits [NiFe]H 2ase by complexing to the Fe II center.. |
| 94. |
Matsumoto, Takahiro; Kabe, Ryota; Nonaka, Kyoshiro; Ando, Tatsuya; Yoon, Ki-Seok; Nakai, Hidetaka; Ogo, Seiji, Model Study of CO Inhibition of [NiFe]hydrogenase, Inorganic Chemistry, 50, 8902-8906, 2011.08. |
| 95. |
Zheng, Chunbai; Kim, Kyoungmok; Matsumoto, Takahiro; Ogo, Seiji, The Useful Properties of H2O as a Ligand of a Hydrogenases Mimic, Dalton Transactions , 10.1039/b921273f, 39, 9, 2218, 2010.03. |
| 96. |
Ichikawa, Koji; Nonaka, Kyoshiro; Matsumoto, Takahiro; Kure, Bunsho; Yoon, Ki-Seok; Higuchi, Yoshiki; Yagi, Tatsuhiko, Ogo, Seiji, Concerto Catalysis — Harmonising [NiFe]hydrogenase and NiRu Model Catalysts, Dalton Transactions, 10.1039/b926061g, 39, 12, 2993, 2010.03. |
| 97. |
Kizaki, Tetsuro; Matsumoto, Takahiro; Ogo, Seiji, Dissolved N2 Sensing by pH-dependent Ru Complexes, Dalton Transactions, 10.1039/b918940h, 39, 5, 1339, 2010.02. |
| 98. |
Kizaki, Tetsuro; Abe, Takeru; Matsumoto, Takahiro; Ogo Seiji, A pH-Stable Ruthenium(II)-based Sensing System for Dissolved Dinitrogen, Chemistry Letters, 10.1246/cl.2010.128, 39, 2, 128, 2010.01. |
| 99. |
Zheng, Chunbai; Inoki, Daisuke; Matsumoto, Takahiro; Ogo, Seiji, An Acid-Stable Organoruthenium Complex Suitable as a Bidentate Building Block, Chemistry Letters, 10.1246/cl.2010.130, 39, 2, 130, 2010.01. |
| 100. |
Takahiro Matsumoto, Kei Ohkubo, Kaoru Honda, Akiko Yazawa, Hideki Furutachi, Shuhei Fujinami, Shunichi Fukuzumi, Masatatsu Suzuki, Aliphatic C-H bond activation initiated by a (μ-η2
η2-peroxo)dicopper(II) complex in comparison with cumylperoxyl radical, Journal of the American Chemical Society, 10.1021/ja809822c, 131, 26, 9258-9267, 2009.07, A (μ-η2:η2-peroxo)dicopper(II) complex, [Cu2(H-L)(O2)]2+ (1-O2), supported by the dinucleating ligand 1,3-bis[bis(6-methyl-2-pyridylmethyl)aminomethyl] benzene (H-L) is capable of initiating C-H bond activation of a variety of external aliphatic substrates (SHn): 10-methyl-9,10-dihydroacridine (AcrH2), 1,4-cyclohexadiene (1,4-CHD), 9,10-dihydroanthracene (9,10-DHA), fluorene, tetralin, toluene, and tetrahydrofuran (THF), which have C-H bond dissociation energies (BDEs) ranging from ∼75 kcal mol-1 for 1,4-CHD to ∼92 kcal mol-1 for THF. Oxidation of SH n afforded a variety of oxidation products, such as dehydrogenation products (SH(n-2)), hydroxylated and further-oxidized products (SH(n-1)OH and SH(n-2)=O), dimers formed by coupling between substrates (H(n-1)S-SH(n-1)) and between substrate and H-L (H-L-SH(n-1)). Kinetic studies of the oxidation of the substrates initiated by 1-O2 in acetone at -70°C revealed that there is a linear correlation between the logarithms of the rate constants for oxidation of the C-H bonds of the substrates and their BDEs, except for THF. The combination of this correlation and the relatively large deuterium kinetic isotope effects (KIEs), k2H/k2D (13 for 9,10-DHA, ≳29 for toluene, and ∼34 for THF at -70°C and ∼9 for AcrH2 at -94°C) indicates that H-atom transfer (HAT) from SHn (SDn) is the rate-determining step. Kinetic studies of the oxidation of SHn by cumylperoxyl radical showed a correlation similar to that observed for 1-O2, indicating that the reactivity of 1-O2 is similar to that of cumylperoxyl radical. Thus, 1-O 2 is capable of initiating a wide range of oxidation reactions, including oxidation of aliphatic C-H bonds having BDEs from ∼75 to ∼92 kcal mol-1, hydroxylation of the m-xylyl linker of H-L, and epoxidation of styrene (Matsumoto, T.; et al. J. Am. Chem. Soc. 2006, 128, 3874).. |
| 101. |
Koji Ichikawa, Takahiro Matsumoto, Seiji Ogo, Critical aspects of [NiFe]hydrogenase ligand composition, Dalton Transactions, 10.1039/b819395a, 22, 4304-4309, 2009.06, Structural analysis of the resting state of [NiFe]hydrogenase ([NiFe]H 2ase) shows that the active site has a characteristic bis(μ-thiolato)NiFe unit, where the Ni atom and the Fe atom are bridged by an undetermined oxygen-bearing ligand. This ligand probably derives from the aqueous solvent and is therefore most likely to be H2O, OH - or O2-. Here, we compare the reactivities of a NiFe and a NiRu complex when bearing either acetonitrile or aqueous ligands and demonstrate the critical role of an aqueous ligand in hydrogenase and its mimics. We also make observations on the necessity of organometallic metal-carbon bonds to the supporting frameworks.. |
| 102. |
Kaoru Honda, Jaeheung Cho, Takahiro Matsumoto, Jungyun Roh, Hideki Furutachi, Takehiko Tosha, Minoru Kubo, Shuhei Fujinami, Takashi Ogura, Teizo Kitagawa, Masatatsu Suzuki, Oxidation reactivity of bis(m-oxo) dinickel(iii) complexes
Arene hydroxylation of the supporting ligand, Angewandte Chemie - International Edition, 10.1002/anie.200900222, 48, 18, 3304-3307, 2009.04, In the nick(el) of time: Bis(μ-oxo) dinickel(III) complexes 2 (see scheme), generated in the reaction of 1 with H2O2, are capable of hydroxylating the xylyl linker of the supporting ligand to give 3. Kinetic studies reveal that hydroxylation proceeds by electrophilic aromatic substitution. The lower reactivity than the corresponding μ - η2: η2 - peroxo dicopper(II) complexes can be attributed to unfavorable entropy effects.. |
| 103. |
Takahiro Matsumoto, Bunsho Kure, Seiji Ogo, Extraction of electrons from H2 with a NiIRu I catalyst, Chemistry Letters, 10.1246/cl.2008.970, 37, 9, 970-971, 2008.09, The mechanism of extraction of electrons from H2 catalyzed by hydrogenases has proven challenging to elucidate. Catalytic extraction of electrons from H2 has been achieved by use of a low-valent Ni IRuI complex [NiI(μ-SR)2Ru I(η6-C6Me6)]{μ-SR) 2 = N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)-1,3- propanediamine) as the active catalyst with evolution of H2 under ambient conditions. The electrons extracted from H2 have been used for a catalytic reduction of Cu2+ to Cu0 with the NiRu complexes.. |
| 104. |
Bunsho Kure, Takahiro Matsumoto, Koji Ichikawa, Shunichi Fukuzumi, Yoshiki Higuchi, Tatsuhiko Yagi, Seiji Ogo, PH-Dependent isotope exchange and hydrogenation catalysed by water-soluble NiRu complexes as functional models for [NiFe]hydrogenases, Dalton Transactions, 10.1039/b807555g, 35, 4747-4755, 2008.09, The pH-dependent hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes and hydrogenation of the carbonyl compounds have been investigated with water-soluble bis(μ-thiolate)(μ-hydride)NiRu complexes, NiII(μ-SR)2(μ-H)RuII {(μ-SR)2 = N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)-1, 3-propanediamine}, as functional models for [NiFe]hydrogenases. In acidic media (at pH 4-6), the μ-H ligand of the NiII(μ-SR) 2(μ-H)RuII complexes has H+ properties, and the complexes catalyse the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes. A mechanism of the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes through a low-valent NiI(μ-SR)2RuI complex is proposed. In contrast, in neutral-basic media (at pH 7-10), the μ-H ligand of the Ni II(μ-SR)2(μ-H)RuII complexes acts as H-, and the complexes catalyse the hydrogenation of carbonyl compounds.. |
| 105. |
Atsushi Kunishita, Junji Teraoka, Joseph D. Scanlon, Takahiro Matsumoto, Masatatsu Suzuki, Christopher J. Cramer, Shinobu Itoh, Aromatic hydroxylation reactivity of a mononuclear Cu(II)-alkylperoxo complex, Journal of the American Chemical Society, 10.1021/ja071623g, 129, 23, 7248-7249, 2007.06, Reaction of copper(II) complex 1X supported by the tridentate bis(pyridylmethyl)amine ligand containing m-substituted phenyl groups at the 6-positions of the pyridine rings (LX) with H2O2 in the presence of triethylamine (NEt3) in acetone generates a copper(II)-alkylperoxo species 2X [2-hydroxy-2-hydroperoxypropane (HHPP) adduct]. The alkylperoxo intermediate 2X undergoes an efficient aromatic ligand hydroxylation reaction, producing a phenolate complex 4X via another intermediate 3X. Kinetic studies on the aromatic hydroxylation process are reported together with spectral characterization of 2X.. |
| 106. |
Takahiro Matsumoto, Hideki Furutachi, Shigenori Nagatomo, Takehiko Tosha, Shuhei Fujinami, Teizo Kitagawa, Masatatsu Suzuki, Synthesis and reactivity of (μ-η2:η2-peroxo)dicopper(II) complexes with dinucleating ligands
Hydroxylation of xylyl linker with a NIH shift, Journal of Organometallic Chemistry, 10.1016/j.jorganchem.2006.05.068, 692, 1-3, 111-121, 2007.01, New hexadentate dinucleating ligands having a xylyl linker, X-L-R, were synthesized, where X-L-R = 1,3-bis[bis(6-methyl-2-pyridylmethyl)aminomethyl]-2,4,6-trimethybenzene (Me2-L-Me) and 1,3-bis[bis(6-methyl-2-pyridylmethyl)aminomethyl]-2-fluorobenzene (H-L-F). They form dinuclear copper(I) complexes, [Cu2(X-L-R)]2+ (Me2-L-Me (1) and H-L-F (2)). The copper(I) complexes in acetone at -78 °C react with O2 to produce intra- and intermolecular (μ-η2:η2-peroxo)dicopper(II) species depending on the concentrations of the complexes: both complexes generate intramolecular (μ-η2:η2-peroxo)dicopper(II) species [Cu2(O2)(X-L-R)]2+ (1-O2 and 2-O2) at the concentrations below ∼5 mM, whereas at ∼60 mM, both complexes produce intermolecular (μ-η2:η2-peroxo)dicopper(II) species, which were confirmed by the electronic and resonance Raman spectroscopies. The electronic spectrum of 1-O2 in acetone at concentrations below ∼5 mM showed an absorption band at (λmax = 442 nm, ε = 5600 M-1 cm-1) assignable to the πσ*(O-O)-to-Cu(II) ((d x2 - y2 + d x2 - y2) component) LMCT transition in addition to an intense band attributable to the πσ*(O-O)-to-Cu(II) ((d x2 - y2 - d x2 - y2) component) LMCT transition (λmax = 359 nm, ε = 21000 M-1 cm-1), indicating that the (μ-η2:η2-peroxo)Cu(II)2 core of 1-O2 takes a butterfly structure. Decomposition of 1-O2 resulted in hydroxylation of the 2-position of the xylyl linker with 1,2-methyl migration (NIH shift), suggesting that the hydroxylation reaction proceeds via a cationic intermediate as proposed for closely related (μ-η2:η2-peroxo)Cu(II)2 complexes having a xylyl linker. Kinetic study of the decomposition (hydroxylation of the xylyl linker) of 1-O2 suggests that a stereochemical effect of the methyl group in the 2-position of the xylyl linker has a significant influence on a transition state for decomposition (hydroxylation of the xylyl linker).. |
| 107. |
Masayasu Mizuno, Kaoru Honda, Jaeheung Cho, Hideki Furutachi, Takehiko Tosha, Takahiro Matsumoto, Shuhei Fujinami, Teizo Kitagawa, Masatatsu Suzuki, A mononuclear alkylperoxocopper(II) complex as a reaction intermediate in the oxidation of the methyl group of the supporting ligand, Angewandte Chemie - International Edition, 10.1002/anie.200602477, 45, 41, 6911-6914, 2006.10, Stepwise down : Reaction of[Cu(Me2-tpa)]+ (tpa = bis(6-methyl-2-pyridylmethyl) (2-pyridylmethyl)amine) with H2O 2 results in regioselective oxidation of a methyl group of the Me2-tpa ligand to produce an alkylperoxocopper(II) complex [Cu(Me-tpa-CH2OO)]+ as a reaction intermediate, which undergoes further decomposition to give aldehyde and alcohol copper(I) complexes as well as alkoxo- and carboxylatocopper(II) complexes (see scheme; blue N, green Cu, red O). (Chemical Equation Presented).. |
| 108. |
Takahiro Matsumoto, Hideki Furutachi, Masashi Kobino, Masato Tomii, Shigenori Nagatomo, Takehiko Tosha, Takao Osako, Shuhei Fujinami, Shinobu Itoh, Teizo Kitagawa, Masatatsu Suzuki, Intramolecular arene hydroxylation versus intermolecular olefin epoxidation by (μ-η2:η2-peroxo)dicopper(II) complex supported by dinucleating ligand, Journal of the American Chemical Society, 10.1021/ja058117g, 128, 12, 3874-3875, 2006.03, A discrete (μ-η2:η2-peroxo)Cu(II)2 complex, [Cu2(O2)(H-L)]2+, is capable of performing not only intramolecular hydroxylation of a m-xylyl linker of a dinucleating ligand but also intermolecular epoxidation of styrene via electrophilic reaction to the C=C bond and hydroxylation of THF by H-atom abstraction.. |
| 109. |
Takahiro Matsumoto, Mariko Umeda, Munenori Numata, Teruaki Hasegawa, Kazuo Sakurai, Kazuya Koumoto, Seiji Shinkai, Poly(N-substituted-acrylamide)-branched schizophyllans are useful for selective recovery of homopolynucleotides through convenient and quick precipitation procedures, Polymer Journal, 10.1295/polymj.37.177, 37, 3, 177-185, 2005.05, Schizophyllans carrying poly(N-substituted-acrylamidej-branches were synthesized from native schizophyllan through Ce(IV)-initiated radical homo- or co-polymerization of N-iso-propyl- and N-sec-butyl-acryl-amide. A series of structural analyses including elemental analysis, gel permeation chromatography, 1H NMR, and enzymatic degradation using β-1,3-glucanase revealed that schizophyllans (150 kDa) bearing long poly(N-substituted- acrylamide)-branches (ca. 290 kDa) are obtained. These SPG-conjugates form macromolecular complexes with certain homopolynucleotides such as poly(C), poly(dA), and poly(A) and then efficiently co-precipitate them on heating. For example, schizophyllan carrying poly(N-iso-propylacrylamide)-branches can selectively recover poly(C) from a mixture of poly(C) and poly(U) by simple heating (36°C) followed by centrifugation. HPLC analysis of the recovered polynucleotide revealed the high poly(C)-selectivity (poly(C):poly(U) = 95:5). Similarly, schizophyllan carrying more hydrophobic poly(N-iso-propylacrylamide- co-N-sec-butylacrylamide)-branches precipitates at lower temperature (ca. 20°C) and is applicable to isolation of poly(A) that forms less stable macromolecular complexes with SPG and SPG-derivatives (the dissociation temperatures are around 30°C).. |
| 110. |
Kyosuke Itoh, Hideki Hayashi, Hideki Furutachi, Takahiro Matsumoto, Shigenori Nagatomo, Takehiko Tosha, Shoichi Terada, Shuhei Fujinami, Masatatsu Suzuki, Teizo Kitagawa, Synthesis and reactivity of a (μ-1,1-hydroperoxo)(μ-hydroxo) dicopper(II) complex
Ligand hydroxylation by a bridging hydroperoxo ligand, Journal of the American Chemical Society, 10.1021/ja047437h, 127, 14, 5212-5223, 2005.04, A new tetradentate tripodal ligand (L3) containing sterically bulky imidazolyl groups was synthesized, where L3 is tris(1-methyl-2-phenyl-4- imidazolylmethyl)amine. Reaction of a bis(μ-hydroxo)dicopper(II) complex, [Cu2(L3)2(OH)2]2+ (1), with H 2O2 in acetonitrile at -40 °C generated a (μ-1,1-hydroperoxo)dicopper(II) complex [Cu2(L3) 2(OOH)(OH)]2+ (2), which was characterized by various physicochemical measurements including X-ray crystallography. The crystal structure of 2 revealed that the complex cation has a Cu2(μ-1,1- OOH)(μ-OH) core and each copper has a square pyramidal structure having an N3O2 donor set with a weak ligation of a tertiary amine nitrogen in the apex. Consequently, one pendant arm of L3 in 2 is free from coordination, which produces a hydrophobic cavity around the Cu 2(μ-1,1-OOH)(μ-OH) core. The hydrophobic cavity is preserved by hydrogen bondings between the hydroperoxide and the imidazole nitrogen of an uncoordinated pendant arm in one side and the hydroxide and the imidazole nitrogen of an uncoordinated pendant arm in the other side. The hydrophobic cavity significantly suppresses the H/D and 16O/18O exchange reactions in 2 compared to that in 1 and stabilizes the Cu 2(μ-1,1-OOH)(μ-OH) core against decomposition. Decomposition of 2 in acetonitrile at 0 °C proceeded mainly via disproportionation of the hydroperoxo ligand and reduction of 2 to [Cu(L3)]+ by hydroperoxo ligand. In contrast, decomposition of a solid sample of 2 at 60 °C gave a complex having a hydroxylated ligand [Cu2(L3)(L3-OH)(OH) 2]2+ (2-(L3-OH)) as a main product, where L3-OH is an oxidized ligand in which one of the methylene groups of the pendant arms is hydroxylated. ESI-TOF/MS measurement showed that complex 2-(L3-OH) is stable in acetonitrile at -40 °C, whereas warming 2-(L3-OH) at room temperature resulted in the N-dealkylation from L3-OH to give an N-dealkylated ligand, bis(1-methyl-2-phenyl-4-imidazolylmethyl)amine (L2) in ∼80% yield based on 2, and 1-methyl-2-phenyl-4-formylimidazole (Phim-CHO). Isotope labeling experiments confirmed that the oxygen atom in both L3-OH and Phim-CHO come from OOH. This aliphatic hydroxylation performed by 2 is in marked contrast to the arene hydroxylation reported for some (μ-1,1-hydroperoxo)dicopper(II) complexes with a xylyl linker.. |
| 111. |
Atsushi Ikeda, Akinori Ejima, Koji Nishiguchi, Jun Ichi Kikuchi, Takahiro Matsumoto, Tsukasa Hatano, Seiji Shinkai, Masahiro Goto, DNA-photocleaving activities of water-soluble carbohydrate-containing nonionic homooxacalix[3]arene·[60]fullerene complex, Chemistry Letters, 10.1246/cl.2005.308, 34, 3, 308-309, 2005.03, A new water-soluble carbohydrate-containing "nonionic" homooxacalix[3]arene (2) was synthesized. 2 could solubilize [60]fullerene (C60) into water and the resultant complex acted as an efficient DNA photocleaving reagent.. |
| 112. |
Teruaki Hasegawa, Tomohisa Fujisawa, Munenori Numata, Takahiro Matsumoto, Mariko Umeda, Ryouji Karinaga, Masami Mizu, Kazuya Koumoto, Taro Kimura, Shiro Okumura, Kazuo Sakurai, Seiji Shinkai, Schizophyllans carrying oligosaccharide appendages as potential candidates for cell-targeted antisense carrier, Organic and Biomolecular Chemistry, 10.1039/b412124b, 2, 21, 3091-3098, 2004.11, Schizophyllans carrying β-lactoside and α-mannoside appendages were prepared from native schizophyllan through NaIO4 oxidation followed by reductive amination using aminoethyl-β-lactoside and α-mannoside, respectively. The resulting schizophyllans form stable macromolecular complexes with polynucleotides, such as poly(C) and poly(dA). Specific affinity between these macromolecular complexes and saccharide-binding proteins was demonstrated by surface plasmon resonance and agarose gel staining assays. β-Lactoside-appended schizophyllan enhanced an antisense activity in hepatocytes which express lactoside-binding proteins on their cell surfaces.. |
| 113. |
Teruaki Hasegawa, Tomohisa Fujisawa, Munenori Numata, Mariko Umeda, Takahiro Matsumoto, Taro Kimura, Shiro Okumura, Kazuo Sakurai, Seiji Shinkai, Single-walled carbon nanotubes acquire a specific lectin-affinity through supramolecular wrapping with lactose-appended schizophyllan, Chemical Communications, 10.1039/b407409b, 19, 2150-2151, 2004.11, Single-walled carbon nanotubes can be entrapped within a helical superstructure composed of schizophyllan bearing lactoside-appendages to show an excellent water-solubility as well as a specific lectin-affinity.. |
| 114. |
Masami Mizu, Kazuya Koumoto, Takahisa Anada, Takahiro Matsumoto, Munenori Numata, Seiji Shinkai, Takeshi Nagasaki, Kazuo Sakurai, A polysaccharide carrier for immunostimulatory CpG DNAs to enhance cytokine secretion, Journal of the American Chemical Society, 10.1021/ja031978+, 126, 27, 8372-8373, 2004.07, A β-(1 → 3)-D-glucan schizophyllan (SPG) forms a stoichiometric complex with some polynucleotides. This communication describes our attempt to apply the SPG complex to deliver CpG DNA to endosomes to enhance cytokine secretion. To increase cellular uptake, we introduced spermine, arginine-glycine-aspartic acid tripeptide, octaarginine, or cholesterol to the SPG side chain. The chemically modified SPG showed essentially no cytotoxicity. When CpG DNA complex made therefrom was exposed to macrophages, dramatic enhancement in the cytokine secretion was observed. It increased 5-10 times from the naked dose and 100 times from the background. This performance promises that SPG can be an excellent carrier for CpG DNA.. |
| 115. |
Takahiro Matsumoto, Munenori Numata, Takahisa Anada, Masami Mizu, Kazuya Koumoto, Kazuo Sakurai, Takeshi Nagasaki, Seiji Shinkai, Chemically modified polysaccharide schizophyllan for antisense oligonucleotides delivery to enhance the cellular uptake efficiency, Biochimica et Biophysica Acta - General Subjects, 10.1016/j.bbagen.2003.10.019, 1670, 2, 91-104, 2004.01, Schizophyllan is a natural β-(1→3)-D-glucan existing as a triple helix in water and as a single chain in dimethylsulfoxide (DMSO), respectively. As we already reported, when some homo-phosphodiester polynucleotide (for example, poly(dA) or poly(C)) is added to the schizophyllan/DMSO solution and subsequently DMSO is exchanged for water, the single chain of schizophyllan forms a complex with the polynucleotide. Furthermore, we have already demonstrated that one of the potential applications of this novel complex is an antisense-oligonucleotide (AS ODN) carrier. This work describes a versatile and universal modification technique which enables us to introduce various functional groups only to the side chain of schizophyllan. This technique consists of periodate oxidation of the glucose side chain (it does not react with the main chain because of the absence of the 1,2-diol group in β-(1→3)-glucan) and subsequent introduction of the functional groups into the formyl terminate. In the present work, the introduced functional groups were spermine, octa-arginine (R8), arginine-glycine-aspartic acid tripeptide (RGD) and some amino or α-amino acid compounds. Using these compounds, we made the complexes and carried out an in vitro antisense assay for them, administrating a phosphorothioate AS ODN to the melanoma A375 or leukemia HL-60 cell lines to depress their c-myb mRNA. When we used the R8 or RGD modified schizophyllan as the antisense carrier, the antisense effect was most enhanced among others. Their superiority can be ascribed to enhancement of endocytosis due to these functional peptides. Furthermore, the cytotoxicity for these two modified schizophyllans was negligibly as small as the natural (unmodified) schizophyllan. One of the peculiar features of our system is that the complex (i.e., carrier+AS ODN) is charged negatively in total, which is different from the conventional systems. The present work has thus clarified that schizophyllan can act as a new potential candidate for AS ODN carriers.. |
| 116. |
Teruaki Hasegawa, Mariko Umeda, Takahiro Matsumoto, Munenori Numata, Masami Mizu, Kazuya Koumoto, Kazuo Sakurai, Seiji Shinkai, Lactose-appended schizophyllan is a potential candidate as a hepatocyte-targeted antisense carrier, Chemical Communications, 10.1039/b313426a, 4, 4, 382-383, 2004.01, A schizophyllan (β-1,3-glucan) derivative carrying lactose-appendages prepared by reductive amination can form stable macromolecular complexes with polynucleotides, shows excellent affinity with a lactose-binding lectin, and effectively mediates gene transfection into hepatocytes.. |
| 117. |
Kazuya Koumoto, Mariko Umeda, Munenori Numata, Takahiro Matsumoto, Kazuo Sakurai, Toyoki Kunitake, Seiji Shinkai, Low Mw sulfated curdlan with improved water solubility forms macromolecular complexes with polycytidylic acid, Carbohydrate Research, 10.1016/j.carres.2003.09.022, 339, 1, 161-167, 2004.01, The water solubility of curdlan was enhanced by partial sulfation at O-6. Circular dichroism measurements suggest that the sulfated curdlan with the degree of substitution (DS) from 0 to 8.7mol% forms macromolecular complexes with polycytidylic acid (poly(C)). Although the thermal stability of the complexes decreased with increase in DS, this could be overlapped by addition of NaCl in the concentration above that of serum. The results clearly indicate that the drawback arising from the electrostatic repulsion between the anionic charges can be partially compensated by the presence of salt. Furthermore, the polynucleotide chain complexed with the sulfated curdlan was protected from the enzymatic hydrolysis, corroborating the assumption that the sulfated curdlan has an ability to bind poly(C).. |
| 118. |
Munenori Numata, Takahiro Matsumoto, Mariko Umeda, Kazuya Koumoto, Kazuo Sakurai, Seiji Shinkai, Polysaccharide-polynucleotide complexes (15)
Thermal stability of schizophyllan (SPG)/poly(C) triple strands is controllable by α-amino acid modification, Bioorganic Chemistry, 10.1016/S0045-2068(03)00020-8, 31, 2, 163-171, 2003.04, Schizophyllan (SPG), a β-1,3-glucan polysaccharide which is known to form macromolecular complexes with certain polynucleotides, was modified by a reductive amination method with α-amino acids (Arg, Lys, and Ser). The thermal stability of the complexes as estimated by Tm was enhanced in SPG-Arg and SPG-Lys conjugates which have pI values higher than the pH of the medium (8.0). The Tm shift increased with the increase in the percentage of α-amino acid introduced and the highest Tm values attained were 64°C for SPG-Arg conjugate and 62°C for SPG-Lys conjugate, which are higher by 13 and 11°C, respectively, than those of the unmodified SPG+poly(C) complex. In the SPG-Ser conjugate with a pI lower than the medium pH (8.0), the Tm values decreased with an increase in the percentage of Ser. Formation of the macromolecular complex was no longer detected above 13.2% Ser. The findings indicate that the Tm values are easily controllable by the type and percentage of the introduced α-amino acids. We believe, therefore, that the present conjugates, consisting of naturally originated SPG and α-amino acids, provide an important lead for developing nontoxic artificial vectors and to control the affinity with polynucleotides in response to medium pH and temperature.. |
