Mechanistic analysis of metal-oxygen active species and their synthetic application to new catalytic oxidation

金属氧活性物质的机理分析及其在新型催化氧化中的合成应用

• 批准号: 17350029
• 负责人: TANI Fumito
• 金额: $ 9.66万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17350029/
• 关键词: oxygen; transition metal ion; iron; oxidation; molecular catalyst; porphyrin; 金属イオン; oxygen; transition metal ion; iron; oxidation; molecular catalyst; porphyrin; 金属イオン

This study is intended to clarify the dioxygen activation process by artificial model complexes for heme enzymes through the spectroscopic characterization of the reactive intermediates such as peroxo-and hydroperoxo heme species, which are generated by the cryoradiolysis with γ-ray (one-electron reduction) of the corresponding dioxygen adducts. The employed complexes have the mimics of the essential functional groups, a) axial ligand, b) hydrogen bondings toward dioxygen, found in the active sites of heme enzymes. The resulting species from the 2K-cryoradiolysis of oxy-complex was assignable to a low-spin six-coordinated peroxoferric heme. After annealing at 133K, a hydroperoxo species was formed. These results confirm that the present complex can reproduce the first important part of the dioxygen activation process composed of the reduction of the coordinated dioxygen and the protonation of the resulting peroxo group.Iron porphyrin complexes, which bear four or two naphtholic hydroxyl groups in the vicinity of the metal center, were synthesized as models of prostaglandin H synthase. In the catalytic cycle of this enzyme, the tyrosyl residue is oxidized to the phenoxyl radical, which abstracts the specific hydrogen atom of the polyolefinic substrate. The present model complexes were oxidized with peroxy acid to give the active species composed of naphthoxyl radical and ferryl ion, as observed in the enzyme. The active species can oxidize non-conjugated diene substrate to the corresponding hydroperoxide with the recovery of the starting naphthol-appended ferric complex. The structure of one of the model complexes was determined by X-ray crystallography.

这项研究旨在通过人工模型复合物通过反应性中间体（例如Peroxo和Hydroperoxo Heme物种）的光谱表征来阐明血红素酶的二氧化激活过程，这些酶是由与γ射线（一部分还原）相应的Dioxy dioxy gen gen gen gen gen gen gen gen gen gen gen gen gen gen gen gen gryodoxo产生的。员工复合物具有基本官能团的模拟物，a）轴向配体，b）在血红素酶的活性位点发现的氢键朝向二恶英。从氧气复合物的2k-氯二二综合分析中产生的物种被分配给低自旋的六协调的过氧脑血红素。在133k处退火后，形成了水氟氧化物种。 These results confirm that the present complex can reproduce the first important part of the dioxygen activation process composed of the reduction of the coordinated dioxygen and the protonation of the resulting peroxo group.Iron porphyrin complexes, which bear four or two naphtholic hydroxyl groups in the vicinity of the metal center, were synthesized as models of prostaglandin H synthase.在该酶的催化循环中，将酪酶残基氧化为苯氧基自由基，该苯氧基自由基抽象了聚油基底物的特定氢原子。如在酶中观察到的那样，用过氧酸氧化了本模型复合物，从而产生了由萘自由基和渡轮离子组成的活性物种。活性物种可以随着起始萘酚易于的铁络合物的恢复，可以氧化二氧化二烯底物与相应的氢过氧化物。通过X射线晶体学确定了其中一个模型复合物的结构。