Bioinspired Structure/Function Studies that Leverage Proton-Responsive Secondary Coordination Spheres and Ligand-Based Redox Sites

项目摘要/摘要 本更新方案中描述的研究的目的是继续开发独特的和创新的 生物启发的络合物将金属酶活性中心的活性和选择性转化为合成的领域 构建了用于研究生物相关反应的结构。许多金属酶催化的反应包括 底物的氧化或还原，对维持人类健康至关重要，以及这些化学变化 通常是多电子氧化还原过程。其中一个过程是亚硝酸盐(NO2-)和硝酸盐的反硝化 (第三名)。NO3-和NO2-是已知的水污染物和可疑的致癌物质，就NO2-而言。关键的一步 在反硝化途径中形成N-N键，形成N2O。具有反硝化能力的系统，以及N- 尤其是N键形成反应，对于阐明N2O的形成机理是至关重要的。我们计划探索 通过不断开发仿生金属配体络合物来实现反硝化的关键反应 含有能够诱导阴离子络合的二次配位球，并与 单一金属-配基结构中基于配基的氧化还原活性部位。我们将继续利用氧化还原活性 吡啶二亚胺(PDI)支架，因为它可以解耦二次配位球的电荷态 从基于配体的氧化还原活性部位得到的络合物。可以独立地调整两个结构 金属-配体支架的性质(二次配位球)和氧化还原性质(基于配体 氧化还原活性中心)独立进行。我们认为这种方法是一种创新和有效的建模方法 金属酶的活性，并提供对化学反应的调节控制。一系列的结构- 功能关系将利用这些新的结构基序来探索通过NOx结合的脱氮作用 还原，包括N-N偶联生成N2O。这些研究将提供一个基本的理解 有必要为可用于反硝化反应的金属-配体结构提供蓝图。 最终，这项研究将导致一种新的复合体，它展示了对反应性的优雅控制，即 灵感来自金属酶。 具体目标包括： (1)开发一类用于NOx结合和还原的双位氢键供体受体。 (2)研究氮氧化物来源的N-N键形成反应。 (3)利用二次配位球内的电场激发NOx反应活性。

Project Summary/Abstract The aim of the research described in this renewal proposal is to continue to develop unique and innovative bioinspired complexes to translate metalloenzyme active site reactivity and selectivity into the realm of synthetic constructs for the study biologically relevant reactions. Many metalloenzymes catalyze reactions that involve either oxidation or reduction of substrate, vital for maintaining human health, and these chemical transformations are generally multi-electron redox processes. One such process is the denitrification of Nitrite (NO2-) and nitrate (NO3-). NO3- and NO2- are known water pollutants and suspected carcinogens, in the case of NO2-. A key step in the denitrification pathway is the N-N bond formation to form N2O. Systems capable of denitrification, and N– N bond-forming reactions in particular, are vital to elucidate the mechanism of N2O formation. We plan to explore key reactions in denitrification through the continued development of bioinspired metal ligand complexes containing secondary coordination spheres capable of enticing anion complexation and merging those with ligand-based redox-active sites within a single metal-ligand construct. We will continue to utilize the redox-active pyridinediimine (PDI) scaffold, as it is possible to uncouple the charge state of the secondary coordination sphere of the complex from the ligand-based redox-active sites. It is possible to independently tune both the structural properties of the metal-ligand scaffolds (secondary coordination sphere) and the redox properties (ligand-based redox active sites) independently. We propose that this approach is an innovative and effective way to model the reactivity of metalloenzymes and provide regulatory control over chemical reactions. A series of structure- function relationships will leverage these novel structural motifs to explore denitrificaiton through NOx- binding and reduction, including N-N coupling to form N2O. These studies will provide a fundamental understanding necessary to provide a blueprint for metal-ligand constructs that can be tuned for denitrification reactions. Ultimately, this research will lead to a new complexes that display the elegant control over reactivity that is inspired by metalloenzymes. Specific Aims include: (1) Develop a class of ditopic H-bond donating receptors for NOx- binding and reduction. (2) Investigate N-N bond formation reactions from NOx- sources. (3) Utilize electric fields in the secondary coordination sphere to entice NOx- reactivity.