2018年诺贝尔化学奖获得者F. Arnold的重要贡献之一是以氧分子为氧化剂，利用P450工程酶催化反马氏不对称氧化。氧合血红素{FeO2}8与超(过)氧血红素{FeO2}9是其中不可或缺的中间体，其几何与电子结构对于认识催化反应机理至关重要。但过去50余年数个{FeO2}9异构体的报道中，只有一例得到单晶结构验证，严重阻碍了研究进展。针对本课题所面临的困难，我们发挥模型化合物在构效关系中的主动作用，基于前期多组{FeO2}8衍生物的分离，提出类picket fence与类Hangman模型策略；利用其对配体的稳定与诱导作用分离目标产物。19年初，我们初步获得了一例单核{FeO2}9的单晶结构（见研究基础），EPR与穆斯堡尔谱表征正在推进之中。相信在本课题的支持下，定能实现若干{FeO2}9异构体的分离表征，建立几何与电子结构构效关系，推动血红素催化反应机理研究，丰富生物无机化学理论。

The 2018 Nobel Prize in Chemistry is awarded to Frances H. Arnold “for the directed evolution of enzymes”. One of Frances H. Arnold’s achievements in this area is the engineering of a cytochrome P450 enzyme by directed evolution to catalyze metal-oxo–mediated anti-Markovnikov oxidation of styrenes with high efficiency. The enzyme uses dioxygen as the terminal oxidant; oxy-heme {FeO2}8 and super/peroxo heme {FeO2}9 have been known to be important intermediates in the catalytic circle. Therefore, the geometric and electronic structures of the two species are crucial to understand the reaction mechanisms. In the past decades, although several {FeO2}9 derivatives have been proposed, only one single crystal structure has been isolated and reported. In contrast to this, a number of NON-heme oxy/super/peroxo analogues have been synthesized and structurally characterized which substantially extended the research frontiers. Based on our recent achievements on a series of {FeO2}8 derivatives which have been isolated and fully characterized, we propose two model systems in this program, the “picket fence like” and “hangman like” porphyrins. Previous experiences suggested that the protecting groups of the two model systems could stabilize the superoxide and peroxide anions, and facilitate the isolation of crystalline products. Fortunately, just at the beginning of 2019, we have preliminary obtained the first {FeO2}9 single crystal structure. Mössbauer and EPR spectroscopic characterization on the same complex are underway. Inspired by this progress, we expect several {FeO2}9 derivatives would be isolated and investigated under the support of this program. The work would shed lights on the chemical nature of dioxygen activation, reveal new information on the catalytic reaction and enrich the bioinorganic chemistry.