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: 8170124
• 负责人: ERIK C WASINGER
• 金额: $ 0.88万
• 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/8170124
• 关键词: Active Sites; Address; Aerobic; Alcohols; Chemicals; Complex; Computer Retrieval of Information on Scientific Projects Database; Copper; Dioxygen; Electronics; Electrons; Enzymes; Equilibrium; Exhibits; Funding; Galactose Oxidase; Grant; Institution; Investigation; Ions; Ligands; Metals; Modeling; Mononuclear; Oxidation-Reduction; Property; Relative (related person); Research; Research Personnel; Resources; Schiff Bases; Series; Source; Techniques; Temperature; Transition Elements; United States National Institutes of Health; Variant; Work; base; electronic structure; enzyme mechanism; interest; metal complex; metalloenzyme; oxidation; phenolate; phenoxy radical; salen; small molecule

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. 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。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 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，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已被研究出来。已经做好准备了。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络合物可以以两种有限的电子形式存在：金属配体自由基（Mn+（L？））或高价金属络合物（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。