Iron-sulfur cluster electronic structural evolution and its contribution to diverse functionality

该提案建立在申请人在SPP 1927的第一个资助期所取得的成果的基础上，并且已经导致我们自己的小组和其他SPP成员合作发表了五篇论文。该项目的核心是了解自然界和模型系统中复杂铁硫团簇的详细电子结构。最终目标是深入了解这些系统的独特反应性，特别强调氮酶和氢化酶。第一个资助期包括一个光谱学和一个理论导向的研究分支。在光谱取向部分，开发了2p3d共振非弹性x射线散射（RIXS）和x射线磁圆二色性（XMCD）作为Fe/S位局部电子结构的独特探针。理论研究的方向是在详细的基于第一性原理波函数计算的基础上开发新的哈密顿量模型，这将允许计算寡核团簇的光谱观测值，这太复杂了，无法用量子化学严格处理。在本提案中，这两个分支的研究将进一步扩展，并有望最终汇聚成独特的结合实验和理论的方案，以阐明Fe/S位电子结构。为此，我们的2p3d RIXS研究将侧重于获得更高分辨率的数据，进一步增强定量信息。此外，我们将进一步探索XMCD作为研究Fe/S位点的补充，并将其应用于氮酶和氢化酶的活性位点。在实验进展的同时，我们将继续从头推导模型哈密顿量的研究。目前，这些研究涵盖了单体和二聚体铁/硫位点的详细研究。第二个资助期的主要目标是开发必要的框架来处理从三聚体和四聚体到氮酶的FeMoco活性位点的更高核，这是生物学中最复杂的活性位点。我们也将把重点放在发展必要的框架来计算从模型哈密顿处理的磁性和x射线光谱性质。最终，我们希望利用开发的协议来获得对FeS簇组装中自然进化的生物合成途径的电子结构后果的基本见解。除了探索这些新的研究领域外，我们还将继续并加强与frank Meyer、Oliver Einsle和Matthias Boll等人在SPP中的合作努力。

This proposal builds upon the results that the applicants have obtained in the first funding period of the SPP 1927 and that have already led to five publications from our own groups and in collaboration with other SPP members. The project is centered around understanding the detailed electronic structure of complex iron-sulfur clusters in nature and in model systems. The ultimate goal is to develop insight into the unique reactivity of these systems, with special emphasis on nitrogenase and hydrogenase. The first funding period contained a spectroscopy- and a theory-oriented branch of research. In the spectroscopy-oriented part, 2p3d resonant inelastic x-ray scattering (RIXS) and X-ray magnetic circular dichroism (XMCD) have been developed as unique probes of the local electronic structure of Fe/S sites. The theoretical research was directed towards developing new model Hamiltonians on the basis of detailed first-principle wavefunction based calculations that will allow the calculation of spectroscopic observables for oligonuclear clusters, which are too complex to be rigorously treated by quantum chemistry. In the present proposal, both branches of research will be further extended and are expected to eventually converge into unique combined experimental and theoretical protocol for the elucidation of Fe/S site electronic structure. To this end, our 2p3d RIXS studies will focus on obtaining higher resolution data to further enhance the quantitative information. In addition, we will further explore XMCD as a complementary, powerful technique for the study of Fe/S sites and will apply it to the active sites of nitrogenase, as well hydrogenase. In parallel with the experimental developments, we will continue our studies on ab initio derived model Hamiltonians. Presently, these studies cover monomeric and dimeric Fe/S sites in detail. The major goal of the second funding period is to develop the necessary framework to treat higher nuclearities from trimers and tetramers, all the way to the FeMoco active sites of nitrogenase, the most complex active site in biology. We will also put major emphasis on developing the necessary framework to calculate magnetic and X-ray spectroscopic properties from the model Hamiltonian treatment. Eventually, we hope to utilize the developed protocols to obtain fundamental insights into the electronic structural consequences of nature’s evolved biosynthetic pathways in FeS cluster assembly. In addition to exploring these new research areas, we will continue and intensify our collaborative efforts in the SPP with the groups of Franc Meyer, Oliver Einsle and Matthias Boll, among others.