DIOXYGEN ACTIVATION BY MODEL COPPER COMPLEXES

本文所述研究的广泛和长期目标 应用是对化合物的结构、电子和化学的阐明。 含金属铜酶配位性质的研究 可逆地结合和/或激活氧气或氧气类似物(硝酸盐 氧化物)。其方法是合成类比方法，以 金属生物分子的活性部位，低分子量 配合物是在小分子水平上合成和检测的。 细节。因此，所揭示的性质是金属络合物固有的 不受蛋白质基质的影响。拟议的研究 最终针对的是组装和表征 三核铜团簇，模拟结构和反应性 蓝色氧化物酶中发现的三核铜团簇，这是 用于将氧气还原为水。激活的机制是 与双核铜中心显著不同的是 酪氨酸酶或血蓝蛋白，尽管结构上存在相似性。一个完整的 对合成的三聚铜的氧气反应性的理解 综合体将有助于澄清一些现有的结构性差异 在结晶学和光谱学之间。这一分析需要研究。 不仅是三核中心，还包括相关的单体和 二聚铜络合物。配体的设计和合成是不可或缺的一部分。 这项研究的进展；合成配基系统的发展 必要的灵活性以适应不同的几何偏好 铜-II和铜-I，同时仍然保持一个预先形成的组织，是 这项提议的一个必要目标。建议的具体目标 主要研究内容如下：(1)Mu-EtA_2：EtA_2Cu2-O_2-L2的表征 具有简单单体配体的铜络合物在低温下可 定义满足以下要求的最小几何约束和电子约束 氧结合和活化；(Ii)合成物的稳定， 四面体铜-II物种在面部封顶，以三氮为配体 提供定义明确的光谱示例，可用作 光谱基准；(Iii)表征和稳定化 一氧化氮和亚硝酸盐与四面体Cu-II的反应中间体 和铜-I络合物，目的是产生与 亚硝酸还原酶的催化循环；(Iv)模块的开发 三核化合物合成中配体组装的合成方法 为稳定铜/氧中间体而设计的铜簇；(V) 结构相似的合成三核铜簇合物的组装 在具有三核配体的抗坏血酸氧化酶中观察到的 它们与氧气的反应性的表征。

The broad and long term objective of the research described in this application is the elucidation of the structural, electronic, and chemical properties of metal-containing coordination sites of copper enzymes that reversibly bind and/or activate dioxygen or dioxygen analogs (nitric oxide). The methodology is that of the synthetic analog approach to the active sites of metallobiomolecules, whereby low molecular weight complexes are synthesized and examined at a small molecule level of detail. The properties revealed are thus intrinsic to the metal complex uncoupled from the influences of the protein matrix. The proposed research is ultimately directed towards the assembly and characterization of trinuclear copper clusters that mimic the structure and reactivity of the trinuclear copper clusters found in blue oxidases, which are responsible for reduction of dioxygen to water. The mechanism of activation is dramatically different from that of the dinuclear copper centers of tyrosinases or hemocyanins, though a structural similarity exists. A full understanding of the dioxygen reactivity of synthetic, trimeric copper complexes will help clarify some of the existing structural disparities between crystallography and spectroscopy. This analysis will require study of, not only the trinuclear centers, but also the related monomeric and dimeric copper complexes. Ligand design and synthesis is an integral part of this research; development of synthetic ligand systems which have the requisite flexibility to accommodate the different geometric preferences of Cu-II and Cu-I, while still maintaining a predisposed organization, is a necessary goal of this proposal. The specific aims of the proposed research are as follows: (i) characterization of mu-eta2:eta2Cu2-O2-L2 copper complexes with simple monomeric ligands at low temperatures to define the minimum geometric and electronic constraints necessary for dioxygen binding and activation; (ii) stabilization of a synthetic, tetrahedral Cu-II species in a facial capping, trinitrogen ligand to provide well defined spectroscopic examples that can be used as spectroscopic benchmarks; (iii) characterization and stabilization of the reaction intermediates of nitric oxide and nitrite with tetrahedral Cu-II and Cu-I complexes with the intention of generating species relevant to the catalytic cycle of nitrite reductase; (iv) development of a modular synthetic approach to ligand assembly for the synthesis of trinuclear copper clusters designed to stabilize copper/dioxygen intermediates; (v) assembly of synthetic trinuclear copper clusters structurally similar to that observed in ascorbate oxidase with trinuclear ligands and characterization of their reactivity with dioxygen.