Synthesis of CO Dehydrogenase Model Complexes for Catalytic Reductions of CO2

描述(申请人提供)：镍酶CODH(一氧化碳脱氢酶)通过微生物代谢在碳循环中发挥关键作用，将二氧化碳转化为细胞碳，因此对地球上的生命至关重要。由于缺乏功能模型络合物，因此本方案旨在制备镍/铁中心类似于CODH的异双金属络合物，目的是回答有关酶功能的问题，并最终设计选择性和高效的二氧化碳还原系统。纯功能模型，即那些用于二氧化碳还原的电催化剂，只包含一种类型的金属离子，并在巨大的过电位下运行。需要新的合成CODH模型络合物来阐明产生结构上忠实的功能模型所需的细节。我们的策略包括合成用于二氧化碳还原的异双金属镍/铁配合物，这在合成化学中是第一次。我们将利用功能化的二亚胺-二肟配体，允许两种不同的金属离子选择性地掺入SIE。这些模型化合物需要解决的问题包括：二氧化碳如何与异双金属Ni/Fe中心结合？刘易斯酸性金属离子如何影响二氧化碳的结合？还原的Ni/Fe中心的结合平衡和活化程度是什么？哪些条件有利于电催化还原二氧化碳？路易斯酸性金属的存在能否提高法拉第效率和/或降低催化所需的过电势？彼得斯实验室适合进行这些研究。乔纳斯·彼得斯教授是合成有机金属和无机化学方面的专家。此外，他在电化学和电催化方法领域拥有丰富的知识。最后，加州理工学院现有的学术环境和设施鼓励丰富的协作讨论，这将确保拟议研究的成功。

DESCRIPTION (provided by applicant): The nickel enzyme CODH (carbon monoxide dehydrogenase) plays a critical role in carbon cycling via microbial metabolism that converts CO2 to cellular carbon and, as such, is essential to life on this planet. Functional model complexes are lacking and thus this proposal aims to prepare heterobimetallic complexes with Ni/Fe centers resembling CODH with the goal to answer questions regarding the enzyme function and ultimately design systems for selective and efficient CO2 reduction. Purely functional models, those that are electrocatalysts for CO2 reduction, contain only one type of metal ion and operate at large overpotentials. New synthetic CODH model complexes are needed to illuminate the details necessary for producing a structurally faithful functional model. Our strategy involves the synthesis of heterobimetallic Ni/Fe complexes for CO2 reduction, a first in synthetic chemistry. We will utilize functionalized diimineo-dioxime ligands that allow sie-selective incorporation of two distinct metal ions. Questions to be addressed with these model complexes include: how does CO2 bind to heterobimetallic Ni/Fe centers? How does the Lewis acidic metal ion affect CO2 binding? What is the binding equilibria and extent of activation at reduced Ni/Fe centers? What conditions favor electrocatalytic reduction of CO2? Can the presence of a Lewis acidic metal improve Faradaic efficiencies and/or lower the overpotential necessary for catalysis? The Peters lab is suited to conduct these studies. Prof. Jonas Peters is an expert in synthetic organometallic and inorganic chemistry. Additionally, he is knowledgeable in the field of electrochemistry and electrocatalytic methods. Finally, the academic environment and facilities available at Caltech encourages rich collaborative discussions that will ensure the success of the proposed studies.