权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

New Oxygen Activation Reaction with Rationally Designed Metal Complexes

合理设计金属配合物的新型氧活化反应

基本信息

批准号：
11228207
负责人：
NARUTA Yoshinori
金额：
$ 38.14万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2002
项目状态：
已结题

项目摘要

The aim of this research is the elucidation of the reaction mechanism working in two enzymes, which play the interconversion between dioxygen and water, respectively. The detailed reaction mechanism for the four-electron reduction of cytochrome c oxidase has not clarified yet, but the role(s)of the each component around the active site is not fully understood. We obtained two major results on these account s with chemical models.1.The oxygenation of the reduced form of N_4Cu complex-tethered heme gave a stable peroxo complex. Its crystal structure was successfully disclosed to show that O_2 bound in a 'side-on' fashion to fom μ-η^2:η^1 structure. This gives a very substantial standpoint to discuss the chemistry of heterodinuclear complexes.2.We prepared CcO active site models, which have a tyrosine-cross linked imidazolate as the part of Cu_B ligand. The correponding peroxide complex showed the different decomposition pathway to give heme Fe(III)-OH/Cu(II). Thus, the phenolic hydroxyl group plays an important role in the reaction of the O_2 complex.Water oxidation is the key reaction to sustain life on the earth. We accomplished stoichiometric oxidation of Mn(III)porphyrin dimer, which has established to catalyze water oxidation under cathodic conditions. Upon oxidation with a peracid, the conesponding Mn(V)-O complex was generated in a good stability and was assigned its structure by spectroscopic methods. This is the first example of Mn(V)=O complex, which is well characterized. By the addition of an acid to the solution of Mn(V)=O spontaneously evolved O_2 in almost quantitative yield. Thus, we succeded to prove that [Mn(V)=O]_2 oxidizes water.

本研究的目的是阐明两种酶的反应机理，这两种酶分别起着分子氧和水之间的相互转化作用。细胞色素c氧化酶四电子还原的详细反应机理尚未阐明，但活性位点周围各组分的作用尚未完全了解。用化学模型研究了这两个问题：1.还原态的N_4Cu络合物-束缚血红素的氧化反应生成稳定的过氧络合物。其晶体结构表明，O_2以“侧边”方式结合形成μ-η^2：η^1结构。2.制备了以酪氨酸交联的咪唑为配体的CcO活性中心模型化合物，该模型化合物的配体为Cu_B。相应的过氧化物络合物表现出不同的分解途径，生成血红素Fe（III）-OH/Cu（II）。因此，酚羟基在O_2络合物的反应中起着重要的作用，水的氧化是维持地球生命的关键反应。我们完成了Mn（III）卟啉二聚体的化学计量氧化，这已建立在阴极条件下催化水氧化。用过酸氧化生成稳定的Mn（V）-O配合物，并通过光谱方法确定了其结构。这是Mn（V）=O配合物的第一个例子，它被很好地表征。在Mn（V）=O的溶液中加入酸，几乎可以定量地自发放出O_2。从而成功地证明了[Mn（V）=O]_2氧化水。