1991 Fiscal Year Final Research Report Summary
STUDIES ON THE STRUCTURE AND CATALYSIS OF NONHEMEIRON COMPLEXES WHICH FUNCTION ENZYME-LIKE CATALYTIC ACTIVITY
| Project/Area Number |
02453078
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
工業物理化学・複合材料
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
FUNABIKI Takuzo KYOTO UNIVERSITY,DEPARTMENT OF HYDROCARBON CHEMISTRY ASSOCIATE PROFESSOR, 工学部, 助教授 (70026061)
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| Co-Investigator(Kenkyū-buntansha) |
TAKANO Mikio KYOTO UNIVERSITY INSTITUTE FOR CHEMICAL RESEARCH PROFESSOR, 化学研究所, 助教授 (70068138)
YOSHIDA Satohiro KYOTO UNIVERSITY,DEPARTMENT OF HYDROCARBON CHEMISTRY PROFESSOR, 工学部, 教授 (00025933)
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| Project Period (FY) |
1990 – 1991
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| Keywords | ENZYME-LIKE FUNCTION / NONHEMEIRON COMPLEXES / CATECHOLDIOXYGENASE / MONOOXYGENASE / HYDROXYLATION / OXYGENATION / CARBONYLATION / IRON-OXENOID ACTIVE SPECIES |
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| Research Abstract |
Structure and function of the model complex of nonheme iron dioxygenases and mono-oxygenases were studied on the bases of product analysis of organic products and spectroscopy of the intermediate iron complexes in the solution. Catecholdioxygenase model reaction was correlated by using catecholatoiron for monooxygenase model reaction.
1.Catecholdioxygenase Model System
On the basis of the catalytic reactivity, we have proposed that the catechol forms catechotoiron(III) complexes which may be in equilibrium with semiquinonatoiron(II) complexes as direct intermediates for the reaction with oxygen. Spectroscopy has indicated the formation of the catecholatoiron(III), but no direct evidence for the semiquinonatoiron(II) has been obtained. In this study we have isolated catecholatoiron(III) complexes. Structure of the complexes in solution was studied spectroscopically, e.g. ESR, Mossbauer, EXAFS, specially by ^1H and ^2H NMR, and the strong radical character of the catecholate ligand , supporting the semiquinonateiron species as an direct active species, has been clearly shown.
2. Monooxygenase Model System
We have developed the catecholoteiron(III) complex/hydroquinones/O2 for the catalytic monooxygenation of aromatics, cyclic and acyclic saturated hydrocarbons in nonaqueous organic solvent such as acetonitile. One of the important and interesting results is the great dependence of selectivity on the pyridine concentration. In the low pyridine concentration, hydroxylation is the main reaction, but in pyridine carbonylation is the main reaction. The reactivity also depends on the substituents on the hydroquinones. Active species was found to be iron-oxygen species rather than the hydroxyl radical.
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