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.

该副本是利用资源的众多研究子项目之一 由NIH/NCRR资助的中心赠款提供。对该子弹的主要支持 而且，副投影的主要研究员可能是其他来源提供的 包括其他NIH来源。 列出的总费用可能 代表subproject使用的中心基础架构的估计量， NCRR赠款不直接向子弹或副本人员提供的直接资金。 铜酶具有二氧化物的一系列反应率，使用小分子模型提供了一种以详细和系统的方式探测酶机制的方法。过渡金属离子和金属酶活性位点中的促血管配体的合作性具有当前的研究意义。一个这样的例子是半乳糖氧化酶（goase），是一种单核铜酶，可催化原发性醇的有氧氧化。为了理解Cu与有机自由基的相互作用的复杂性，已经制备了一系列的Schiff碱基（Salen），半还原盐和完全还原的盐酸CU（II）复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，我们旨在更深入地了解控制其单电子氧化形式中氧化基因座的因素。根据氧化还原活性轨道的相对能量，具有两种限制性电子形式的金属配合物可以存在：金属配体自由基（Mn+（L？））或高的价值金属络合物（M（n+1）+（l-））。在氧化的Cu-salen络合物的情况下，Cu（iii） - 乙酸盐或Cu（II） - 苯氧基自由基物种是可能的，它可能通过配体场和/或温度的变化在价折线平衡中存在。 XAS研究将提供有关这些复合物氧化源的信息，以及稳定这些反应性形式中一种或另一种的电子因素。 XAS是这项工作的一种特别有用的技术，因为它对金属氧化状态特别敏感，并且为理解几何和电子结构如何相互作用（通过K-EDGE，EXAFS和LEDGE的分析）提供了一种手段。这项研究提出的工作解决了生物无机问题，以及一些更基本的化学和光谱问题。