OXIDIZED CU(II)-PHENOLATE COMPLEXES: THE FACTORS GOVERNING LIGAND VS METAL-BASE

氧化铜 (II)-酚盐络合物：配体与金属基的控制因素

• 批准号: 8362173
• 负责人: ERIK C WASINGER
• 金额: $ 0.71万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8362173
• 关键词: Active Sites; Address; Aerobic; Alcohols; Chemicals; Complex; Copper; Dioxygen; Electronics; Electrons; Enzymes; Equilibrium; Exhibits; Funding; Galactose Oxidase; Grant; Investigation; Ions; Ligands; Metals; Modeling; Mononuclear; National Center for Research Resources; Oxidation-Reduction; Principal Investigator; Property; Radiation; Relative (related person); Research; Research Infrastructure; Resources; Schiff Bases; Series; Source; Techniques; Temperature; Transition Elements; United States National Institutes of Health; Variant; Work; base; cost; electronic structure; enzyme mechanism; interest; metal complex; metalloenzyme; oxidation; phenolate; phenoxy radical; salen; small molecule; structural biology

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. Copper enzymes exhibit a range of reactivities with dioxygen and the use of small-molecule models offers a means of probing enzyme mechanism in a detailed and systematic manner. The cooperativity of transition metal ions and pro-radical ligands in metalloenzyme active sites is of current research interest. One such example, Galactose oxidase (GOase), is a mononuclear copper enzyme that catalyzes the aerobic oxidation of primary alcohols. In an effort to understand the intricacies of the interaction of Cu with organic radicals, a series of Schiff-base (salen), half-reduced-salen, and fully reduced-salen Cu(II) complexes and their one-electron oxidized form have been prepared. By tuning the electronic properties of these planar ligands we aim to develop a deeper understanding of the factors that govern the oxidation locus in their one-electron oxidized forms. Depending on the relative energies of the redox-active orbitals, metal complexes with pro-radical ligands can exist in two limiting electronic forms: a metal-ligand radical (Mn+(L?)) or a high valent metal complex (M(n+1)+(L-)). In the case of the oxidized Cu-salen complexes, Cu(III)-phenolate or Cu(II)-phenoxyl radical species are possible, which can potentially exist in a valence tautomeric equilibrium through variation of the ligand field and/or temperature. XAS investigations will provide information on the locus of oxidation of these complexes, and the electronic factors that stabilize one or the other of these reactive forms. XAS is an especially useful technique for this work, as it is specifically sensitive to the metal oxidation state, and as it provides a means for understanding how geometric and electronic structure interact (via analysis of K-edge, EXAFS, and L-edge). The work proposed in this study addresses bioinorganic questions as well as several more fundamental chemical and spectroscopic issues.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的主要研究者可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 铜酶表现出一系列与双氧的反应性，小分子模型的使用提供了一种以详细和系统的方式探索酶机制的方法。金属酶活性位点中过渡金属离子和前自由基配体的协同作用是当前的研究兴趣。一个这样的例子，半乳糖氧化酶（GOase）是一种单核铜酶，可催化伯醇的有氧氧化。为了了解 Cu 与有机自由基相互作用的复杂性，制备了一系列席夫碱 (salen)、半还原 salen 和完全还原 salen Cu(II) 配合物及其单电子氧化形式。通过调整这些平面配体的电子特性，我们的目标是更深入地了解控制单电子氧化形式氧化位点的因素。根据氧化还原活性轨道的相对能量，具有亲自由基配体的金属配合物可以两种限制电子形式存在：金属配体自由基（Mn+(L?)）或高价金属配合物（M(n+1)+(L-)）。在氧化的 Cu-salen 配合物的情况下，Cu(III)-苯酚盐或 Cu(II)-苯氧基自由基物质是可能的，它们可以通过配体场和/或温度的变化潜在地存在于价互变异构平衡中。 XAS 研究将提供有关这些复合物的氧化位点以及稳定这些反应形式中的一种或另一种的电子因素的信息。 XAS 对于这项工作来说是一项特别有用的技术，因为它对金属氧化态特别敏感，并且它提供了一种了解几何结构和电子结构如何相互作用的方法（通过 K 边、EXAFS 和 L 边分析）。这项研究提出的工作解决了生物无机问题以及几个更基本的化学和光谱问题。