VEPES/XAS/DFT STUDIES OF ET SITES IN BIOINORGANIC CHEMISTRY

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 在我们之前提出的研究中，我们一直在价区和金属2p区使用可变能量光电子能谱来探索电子弛豫，即电离还原位置时电子结构的变化。到目前为止，这已被应用于Fe(SR)4位，其中大的电子弛豫(配体与M d CT)限制了氧化电荷的变化，并极大地降低了几何变化(即位的重组能)。我们现在正在完成对一系列单核铁络合物的研究，在这些研究中，我们考察了从高自旋到低自旋、配位数(四面体与八面体)的增加以及配体的变化，以了解血红素连接对[FePP(Imh)2]络合物电子弛豫的贡献。我们现在建议将我们对双-Im血红素络合物的PES研究扩展到双Met Fe(THT)2(TPP)络合物和细胞色素c模型络合物(Fe(C5-Im)(TPP)(THS).C6H6)，其中我们将定量研究MET配体对电子弛豫的影响，并通过密度泛函计算和扩展电荷分解和价键组态相互作用分析将这些结果扩展到cytb和cytc的电子松弛。除了对血红素电子转移中心的电子能谱研究外，我们还将研究蓝铜、铜铜、硫化铜和硫化铁相关模型化合物中的共价性和电子离域及其对电子弛豫的贡献。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. In studies performed during our previous proposals, we have been employing variable energy photoelectron spectroscopy in the valence and metal 2p regions to explore electronic relaxation, the change in electronic structure upon ionization of a reduced site. Thus far, this has been applied to Fe(SR)4 sites where the large electronic relaxation (ligand to M d CT) limits the charge change on oxidation and greatly reduces the geometry change (i.e. the reorganization energy of the site). We are now completing studies on a series of mononuclear Fe complexes in which we examined the effects of going from high to low spin and increased coordination number (tetrahedral vs. octahedral) as well as ligand variation to understand the contribution of heme ligation to electronic relaxation in the [Fetpp(imH)2] complex. We are now proposing to extend our PES studies of the bis-Im heme complex to the bis-met Fe(THT)2(tpp) complex and a cytochrome c model complex (Fe(C5-Im)(tpp)(THS).C6H6) where we will quantitate the effect of the met ligands on electronic relaxation and extend those results to electronic relaxation of cyt b vs. cyt c through DFT calculations and extended charge decomposition and valence bond configuration interaction analyses. In addition to PES studies of heme electron transfer sites, we will investigate covalency and electron delocalization and their contribution to electronic relaxation in blue copper, CuA, and Fe4S4 related model complexes.