| Project/Area Number |
12450327
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
触媒・化学プロセス
|
|---|
| Research Institution | Kyoto University |
|---|
Principal Investigator |
FUNABIKI Takuzo Graduate School of Engineering Professor, 工学研究科, 教授 (70026061)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HITOMI Yutaka Graduate School of Engineering Assistant Professor, 工学研究科, 助手 (20335186)
TANAKA Tsunehiro Graduate School of Engineering Associate Professor, 工学研究科, 助教授 (70201621)
|
|---|
| Project Period (FY) |
2000 – 2002
|
| Project Status |
Completed (Fiscal Year 2002)
|
| Budget Amount *help |
¥14,700,000 (Direct Cost: ¥14,700,000)
Fiscal Year 2002: ¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2000: ¥7,000,000 (Direct Cost: ¥7,000,000)
|
|---|
| Keywords | Nonheme Iron Complexes / Oxygenases / Oxygenase-model Catalysts / Dioxygenases / Manganese Complexes / Water-soluble Nonheme Iron Complexes / Oxygenative Cleavage of Aromatics / Oxygen Activation / 酸素モデル触媒 / 水溶性ヘム鉄錯体 / 3座配位子 / α-ケト酸 |
|---|
| Research Abstract |
Following studies were performed on the development of oxygenase-like catalytic functions by nonheme monoiron complexes and manganese complexes and on the clarification of mechanisms of electron transfer that is essential for activation of substrates.
1)Intradiol and extradiol oxygenative cleavage of catechols by monoiron complexes
Catalytic activity of oxygenations by monoiron complexes ligated by tripodal ligands and tridentate ligands were studied. Effect of electronic and steric effects of substituents on the selective intradiol cleavage gave important information of the oxygen activation and oxygen insertion process into the C-C bonds. In the extraiol cleavage by iron complexes with tridentate ligands also clarified the mechanism of oxygenation via the direct oxygen binding to the iron center. Not only ligands with only the N binding sites but also ligands with N and O binding sites were used for clarification of the O2 insertion into catechols.
2)Intra and extradiol oxygenative clea
… More
vage of catechols by manganese complexes
By mimicking manganese-containing extradiol cleaving oxygenases, Mn(II)-semiquinone complexes were first synthesized. The complexes were found to be oxygenated to give the intradiol cleavage productws. Interestingly, the reversible uptake of oxygen was observed, indicating that the molecular oxygen binds first to the metal center (iron and manganese) prior to binding to the catechol carbon.
3)Oxygenations in water by iron complexes with water-soluble ligands
Although enzymatic oxygenations proceeds in aqueous media, models oxygenations have been performed in organic solvents. This is partly due to the ligands soluble only in organic solvents, and partly on exclusion of oxygen saurce other than molecular oxygen. We have first developed a model system that works in water to give the selective intradiol cleavage of mono-alkyl catechols, e.g. 4-butyl catechols, catechols with the electron-withdrawing substituents, such as chloro and carboxylate, by using the TPA ligands with sulfonate subsitutients. It is important to find that the protocatechuic acid was found to be oxygenatively cleaved by monoiron complexes, because the model oxygenation has not be developed in spite of the most popular enzyme, protocatechuic oxygenases. It was also found that the pH control of the media is essential for the aqueous system. We also found that the TPA complexes without the solfonate substituents are also effective for the reaction in aqueous media. Less
|
