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Spectroscopic and Electrochemical Studies on the Structure and Catalytic Activity of Oxygenase Model Complexes

Research Project

Project/Area Number 01044134
Research Category

Grant-in-Aid for international Scientific Research

Allocation TypeSingle-year Grants
SectionJoint Research
Research InstitutionOsaka Institute of Technology

Principal Investigator

NISHINAGA Akira  Osaka Institute of Technology, Faculty of Engineering, 工学部, 教授 (80025882)

Co-Investigator(Kenkyū-buntansha) BERND Speise  チュービンゲン大学, 化学教室, 教授
ANTON Rieker  チュービンゲン大学, 化学教室, 教授
TAJIMA Kunihiko  Ehime University, Faculty of Science, 理学部, 助手 (50163457)
大矢 博昭  京都大学, 理学部, 助教授 (00025389)
ISHIZU Kazuhiko  Ehime University, Faculty of Science, 理学部, 教授 (60036184)
OHYA-NISHIGUCHI Hiroaki  Kyoto University, Faculty of Science
NISHINAGA Akira  Osaka Institute of Technology, Faculty of Engineering
SPEISER Bernd  Tuebingen University, Institute of Organic Chemistry
RIEKER Anton  Tuebingen University, Institute of Organic Chemistry
Project Period (FY) 1989 – 1990
Project Status Completed (Fiscal Year 1990)
Budget Amount *help
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1990: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1989: ¥3,600,000 (Direct Cost: ¥3,600,000)
KeywordsCobalt Complex / Schiff Base Complex / Oxygenase Model / Peroxo Complex / Ternary Complex / Oxygenation / Redox Potential of Metal Complex / Electron Transfer
Research Abstract

1. As model oxygenase reactions, the following cobalt Schiff base complex, Co (SB), catalyzed oxidations have been newly developed : epoxidation of olefins with NaOCl, monooxygenation of alkynes with oxygen, dehydrogenation of amines with t-butyl hydroperoxide (TBHP). These reactions were sensitive to the structure of Co (SB). With the aim of elucidating the effect of the strutture of Co (SB) on the reactivities, various Co (SB) were synthesized and redox potential E of Co (II) = Co (III) for these complexes were systematically determined. The electrochemical characteristics E was closely related to the strucural factors : a higher E was obtained with complexes having more electron-withdrawing or bulkier groups in the SB ligand, and also with complexes having nonplanar ligands. In the Co (SB) catalyzed epoxidation, the reactive species was found to be a water soluble anionic Co (SB) coordinating C10, and the higher E gives the higher concentration of the active complex. On the other ha … More nd, in the Co (SB) catalyzed monooxygenation of alkenes and alkynes with molecular oxygen, no relation between the reactivity and E was observed, but the shape of the complex plays a more important role. The catalysis of Co (SB) in the dehydrogenation of amines with TBHP is important because of a mimic of the P450 activity. The reactive species in this case is a Co (SB) (t-Bu00) complex. Under the reaction conditions, the peroxo complex decomposes to give ClO, which abstracts electron from the nitrogen atom in the substrate. Single crystal was obtained from a flavonolato-Co (salen), which is unsusceptible to the oxygenolysis in noncoordinative solvents. The X-ray analysis of this complex showed that the substrate anion is coordinated as a bidentate ligand. The NMR studes on this complex in DMF, where the complex undergoes readily oxygenolysis, showed that the substrate anion is coordinated as a monodentate ligand.
2. Spectro-magnetic and electrochemical studies on the oxygenase like activity of Co (SB) and Co (PA) (PA=polyamines) towards catechols showed that starting with a Co (II) catalyst oxygen is first reduced to superoxo species followed by one-electron transfer from the substrate to the resulting Co (III) resulting in the formation of a ternary complex consisting of hydroperoxo-Co (III) -substrate semiquinone. On the other hand, starting from a Co (III) state, proton transfer from the substrate to an anion ligand of the complex followed by electron transfer from the resulting substrate anion to the Co (IIII) center to form a paramagnetic semiquinone complex intermediate, as confirmed by means of magnetic susceptibility method.
3. Spectroscopic parameters related to the structure of heme-peroxide complex as models for the intermediate of oxygenase reactions are systematically accumlated during the research from 1989 to 1990. From the characteristic point of view thus obtained in the spectroscopy, coditions required for the formation of the peroxo heme complexes have been investigated. We find that the addition of sodium salt of ascorbic acid to a Fe (II)-oxygen complex at low temperature gives a 6 coordinate hydrogenperoxido-heme complex.
As another model for a possible intermediate in the tryptophan dioxygenase reaction, the formation of a 6 coordinate heme-organic peroxid complex having a ternary complex structure including synthetic heme, oxygen, and the substrate are confirmed by ESR.
These results are significant in order to give basic knowledge to understand the mechanism of the oxygenation reactions catalyzed by heme in nature. Less

Report

(1 results)
  • 1990 Final Research Report Summary
  • Research Products

    (11 results)

All Other

All Publications (11 results)

  • [Publications] K.Tajima,M.Yoshino,K.Mikami,T.Edo,K.Ishizu,H.OhyaーNishiguchi: "Important Role of Fe(III)TPPーOxygenーSkatole Termary Complex in Tryptophan Dioxygenase Model Reaction System" Inorg.Chim.Acta. 172. 83-91 (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] A.Nishinaga,K.Yoda,K.Maruyama,H.Okamoto: "Oxygenation of Phenylacetylene Catalyzed by Co(salen)" J.Chem.Soc.,Chem.Commun.876-877 (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] K.Tajima,M.Shigematsu,J.Jinno,NK.Ishizu,H.OhyaーNishiguchi: "Generation of Fe(III)OEPーHydrogen Peroxide Complex by Reduction of Fe(II)ーO_2 with Ascorbic Acid Sodium Salt" J.Chem.Soc.,Chem.Commun.144-145 (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] A.Nishinaga,T.Maruyama,M.Kakutani,T.Umeda,T.Mashino: "Cobalt Schiff Base Complex Catalyzed Epoxidation of Olefins with NaOCl" Proc.4th Intern.Symposium on Activation of Dioxygen and Homogeneous Catalytic Oxidation. (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] S.Nakashima,H.OhyaーNishiguchi,N.Hirota,S.Tsuboyama,A.Nishinaga: "Quantitative Formation of Spin Coupled Intermediate in a System Consisting of Co(III)Tetramine Complexes and Catechols" Proc.4th Itern 4th Intern.Symposium on Activation of Dioxygen and Homogeneous Catalytic Oxidation. (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] A.Nishinaga,K.Tajima,B.Speiser,E.Eichhorn,A.Rieker,H.OhyaーNishiguchi,K.Ishizu: "Substituent Effects on the Formal Potential of Co(II)ーCo(III)for Co(salen) Derivbtives" J.Chem Soc.,Chem.Commun. (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] K. Tajima, M. Yoshino, K. Mikami, T. Edo, K. Ishizu, H. Ohya-Nishiguchi: "Important Role of Fe (III) TPP-Oxygen-Skatole Ternary Complex in Tryptophan Dioxygenase Model Reaction System" Inorg. Chim. Acta. 172. 83-91 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] A. Nishinaga, K. Yoda, K. Maruyama, H. Okamoto: "Oxygenation of Phenylacetylene Catalyzed by Co (salen)" J. Chem. Soc., Chem. Commun.876-877 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] A. Nishinaga, T. Maruyama, M. Kakutani, T. Umeda, T. Mashino: "Cobalt Schiff Base Complex Catalyzed Epoxidation of Olefins with NaOCl" Proc. 4th Intern. Symposium on Activation of Dioxygen and Homogeneous Catalytic Oxidation. in press. (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] S. Nakashima, H. Ohya-Nishiguchi, N. Hirota, S. Tsuboyama, A. Nishinaga: "Quantitative Formation of Spin Coupled Intermediate in a System Consisting of Co (III) Tetramine Complexes and Catechols" Proc. 4th Intern. Symposium on Activation of Dioxygen and Homogeneous Catalytic Oxidation. in press. (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] A. Nishinaga, K. Tajima, B. Speiser, E. Eichhorn, A. Rieker, H. Ohya-Nishiguchi, K. Ishizu: "Substituent Effects on the Formal Potential OF Co (II)-Co (III) for Co (salen) Derivatives" J. Chem. Commun. (J. Chem. Soc.). submitted. (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary

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Published: 1989-04-01   Modified: 2016-04-21  

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