PES/DFT STUDIES ON ELECTRONIC STRUCTURE CONTRIBUTIONS TO ELECTRON TRANSFER

电子结构对电子传输贡献的 PES/DFT 研究

• 批准号: 8169972
• 负责人: EDWARD I SOLOMON
• 金额: $ 1.63万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8169972
• 关键词: Biological Models; Complement; Complex; Computer Retrieval of Information on Scientific Projects Database; Cytochromes; Data; Electron Transport; Electronics; Ferredoxin; Funding; Grant; Heme; Institution; Kinetics; Ligands; Metalloproteins; Metals; Methodology; Methods; Modeling; Oxidation-Reduction; Pathway interactions; Process; Property; Relaxation; Research; Research Personnel; Resources; Roentgen Rays; Site; Source; Spectrum Analysis; Structure; Synchrotrons; United States National Institutes of Health; absorption; base; biological systems; density; electronic structure; high potential iron-sulfur protein; insight; metal complex; oxidation; research study; theories

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The major emphasis of our research is to apply variable energy photoelectron spectroscopy (PES) combined with X-ray absorption edge spectroscopy (XAS) to define electronic structure contributions to electron transfer (ET) in biological systems. PES provides a direct method to study inorganic redox processes and the contribution of electronic relaxation to redox properties (E¿, HAB, lambda). The shake-up satellite structure present in core and valence PES data can be used in combination with a valence bond configuration interaction (VBCI) model to experimentally quantify electronic relaxation (i.e. the change in electronic structure of metal complexes upon oxidation) and its contributions to reduction potentials and kinetics of ET. Variable-energy PES experiments provide a mechanism to maximize the metal while minimizing the ligand contributions to the valence band region through cross section effects (delayed maximum and Cooper minimum) and resonance enhancement. Our synchrotron-based studies on simple model systems [FeX4]2-/1 (X=Cl-, -SR) have afforded experimental results that define electronic structure and its changes upon redox. Complemented by density functional theory (DFT) calculations, these studies provide insight into electronic relaxation and allow extension to the metalloprotein sites. Using the methodology developed in the studies on [FeX4]2-/1, we are now examining model heme complexes. The data on the heme models combined with DFT calculations should also allow extention to and define the superexchange pathways for ET in the cytochromes. We will also extend these PES/DFT studies to [Fe4S4(SR)4] systems modeling the 4Fe ferredoxins and HiPIPs (high potential iron proteins), which will provide insight into electronic relaxation and its contributions to the kinetics and pathways for ET in the ferredoxins and HiPIPS.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以出现在其他 CRISP 条目中 列出的机构是。 对于中心来说，它不一定是研究者的机构。 我们研究的重点是应用可变能量光电子能谱 (PES) 与 X 射线吸收边能谱 (XAS) 相结合来定义电子结构对生物系统中电子转移 (ET) 的贡献，为研究无机物提供了一种直接方法。氧化还原过程以及电子弛豫对氧化还原性质的贡献（E¿、HAB、lambda） 核心和价态 PES 数据中存在的震动卫星结构可以与价键构型相互作用结合使用。 (VBCI) 模型用于实验量化电子弛豫（即氧化时金属配合物电子结构的变化）及其对 ET 还原电位和动力学的贡献，可变能量 PES 实验提供了一种最大化金属同时最小化配体贡献的机制。通过截面效应（延迟最大值和库珀最小值）和共振增强我们对简单模型系统 [FeX4]2-/1 (X=Cl-, -SR）提供了定义电子结构及其氧化还原变化的实验结果，并辅以密度泛函理论（DFT）计算，这些研究提供了对电子弛豫的深入了解，并允许使用研究中开发的方法扩展到金属蛋白位点。 [FeX4]2-/1，我们现在正在研究血红素复合物模型，结合 DFT 计算的血红素模型数据也应该允许扩展并定义细胞色素中 ET 的超交换途径。这些针对 [Fe4S4(SR)4] 系统的 PES/DFT 研究模拟了 4Fe 铁氧还蛋白和 HiPIP（高电位铁蛋白），这将深入了解电子弛豫及其对铁氧还蛋白和 HiPIPS 中 ET 动力学和途径的贡献。