Water Oxidation in Synthetic heme Oxidase Models

描述（由申请人提供）：拟议的研究描述了用于将水氧化为分子氧的单核铁催化剂的开发。催化剂设计元素的灵感来自于酶，而分子氧是酶的天然底物。特别是，假设初始O-O键的形成应该是通过活性水分子对高氧化性和亲电性金属氧单元的亲核攻击来实现的。实现这一反应的两个关键因素是：1)产生一个足够活跃的缺电子金属单元，2)在关键的O-O键形成过程中对质子的管理。所提出的催化剂通过表明适当连接的Fe(V)-氧单元将在能量上倾向于与水形成O-O键来解决这些问题。Fe (V)-氧的反应性将通过一种新型的腐蚀衍生的“刽子手”配体来调整，这种配体将氢键功能置于四吡啶赤道环境的平面之上。合成的结构将在初始的Fe(V)-oxo生成和随后的O-O键形成和O2释放两个阶段进行评估。在这方面，提出的机制类似于细胞色素P450功能的微观逆转，其中O2被裂解以提供水和高价铁氧中间体。因此，期望本研究能为细胞色素P450单加氧酶的机制和能量需求提供新的视角。此外，拟议研究的长期成功代表了将水转化为用作燃料的分子氧和氢的可能性的介绍。这一计划将有助于减少全球对化石燃料燃烧的依赖，通过减少环境污染，将大大改善公共卫生，特别是城市地区的公共卫生。与长期接触化石燃料燃烧产生的污染有关的风险是一个日益严重的重大公共卫生问题。因此，采用新的非碳基能源预计将直接改善人类健康，特别是在城市地区。该提案描述了一种水氧化催化剂的设计和评估，该催化剂可用于生产氢（一种无污染燃料）的方案的一部分。

DESCRIPTION (provided by applicant): The proposed research describes the development of a mononuclear iron catalyst for the oxidation of water to molecular oxygen. Inspiration for elements of catalyst design are drawn from enzymes for which molecular oxygen is a natural substrate. In particular, it is hypothesized that initial O-O bond formation should be possible by nucleophilic attack of an activated water molecule on a highly oxidizing and electrophilic oxometal unit. Two factors are critical for realizing this reaction: 1) generation of a sufficiently reactive electron-deficient oxometal unit, and 2) management of protons during the key O-O bond forming event. The proposed catalyst addresses these concerns by suggesting that an appropriately ligated Fe(V)- oxo unit will be energetically disposed to undergo O-O bond formation with water. The reactivity of the Fe (V)-oxo species will be tuned using a new class of corrole-derived 'hangman' ligands, which position hydrogen bonding functionality above the plane of a tetrapyrrolic equatorial environment. The synthesized structures will be evaluated in two stages for initial Fe(V)-oxo generation and then subsequent O-O bond formation and O2 liberation. In this regard, the proposed mechanism resembles the microscopic reverse of cytochrome P450 function, where O2 is cleaved to furnish water and a high-valent iron-oxo intermediate. As such, it is expected that the proposed research will offer perspectives on the mechanism and energetic requirements of the cytochrome P450 monooxygenases. Additionally, long-term success of the proposed research represents an introduction to the possibility of converting water to molecular oxygen and hydrogen for use as fuels. Such a scheme would help reduce global dependence on fossil fuel combustion which would dramatically improve public health, especially in urban areas, by reducing environmental pollution. The risks associated with chronic exposure to pollution from fossil fuel combustion are a major and increasing public health concern. Consequently, the adoption of new non-carbon based energy sources is expected to directly improve human health, especially in urban areas. This proposal describes the design and evaluation of a water oxidation catalyst that could be used as part of a scheme to produce hydrogen, a non-polluting fuel.