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制，这两种酶分别起到双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制尚未阐明，但其作用（ s) 活性位点周围的每个成分尚未完全了解，我们通过化学模型获得了两个主要结果。1. N_4Cu 络合物束缚血红素的还原形式的氧化作用给出了。其晶体结构被成功揭示，表明O_2以“侧向”方式结合形成μ-η^2:η^1结构，这为讨论异双核配合物的化学提供了非常重要的基础。 .2.我们制备了CcO活性位点模型，其具有酪氨酸交联的咪唑酸酯作为Cu_B配体的一部分，相应的过氧化物络合物显示出不同的分解途径以产生血红素。 Fe(III)-OH/Cu(II)。因此，酚羟基在O_2配合物的反应中起着重要作用。水氧化是维持地球生命的关键反应。我们完成了Mn(的化学计量氧化)。 III) 卟啉二聚体，其在阴极条件下催化水氧化，相应的过酸氧化。 Mn(V)-O 络合物的生成具有良好的稳定性，并通过光谱方法确定了其结构，这是 Mn(V)=O 络合物的第一个例子，通过向溶液中添加酸来对其进行了很好的表征。 Mn(V)=O 几乎定量地自发生成 O_2，因此，我们成功证明了 [Mn(V)=O]_2 可以氧化水。