Leveraging a Tetradentate Redox-active Ligand to Enhance Control Over Properties and Reactivity

在化学系化学合成项目的资助下，加州大学欧文分校化学系的Alan Heyduk教授将探索氧化还原活性配体平台的设计和合成，以改善过渡金属离子配位配合物的电子性能和增强反应性模式。该项目的动机是配合物的电子性质和反应模式在不同的研究领域发挥关键作用，例如开发新的光敏材料和发现分别用于合成燃料和商品和精细化学品的催化剂。为了实现改进的电子性能和增强的反应性模式，研究重点是新的配体设计，这些配体设计可以严格控制金属离子的局部配位环境，同时还可以扩大金属离子可获得的氧化态的数量。与加州大学洛杉矶分校的社会本科生研究研讨会合作，为本科生提供研究指导和指导，其中许多来自代表性不足的群体，因为他们准备从STEM领域的研究生学位课程中毕业。本项目主要研究四齿、氧化还原活性配体的开发及其相关过渡金属配位配合物的合成和表征。配体设计包含一个邻苯二胺主链，直接与金属中心协调，由于其自身的三个氧化态在温和电位下可达到，因此增强了金属基氧化还原过程。此外，配体设计包含两个辅助的“臂”，它们也与金属离子结合，在金属中心提供稳定性和空间保护，并提供对局部配位环境的控制。这些配体的设计特点主要体现在两个方面：(a)发展配体到配体的电荷转移发色团；(b)发展多电子、原子和基团转移反应的催化剂。在这个项目中，Heyduk团队将利用无机合成技术来获得新的分子进行研究。新的配合物将通过一系列技术来表征，包括电化学方法、单晶x射线衍射、核磁共振、EPR、紫外-可见-近红外光谱和红外光谱，以及计算方法。所提出的工作的好处和结果包括扩大对氧化还原活性配体如何用于控制和增强过渡金属离子的反应性的理解，以及培训反应性配位配合物的合成、表征和利用方面的熟练劳动力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With funding from the Chemical Synthesis Program in the Chemistry Division, Professor Alan Heyduk in the Department of Chemistry at the University of California, Irvine will explore the design and synthesis of redox-active ligand platforms that engender improved electronic properties and enhanced reactivity patterns in coordination complexes of transition metal ions. The project is motivated by the fact that the electronic properties and reactivity patterns of coordination complexes play a critical role in diverse areas of research such as the development of new photosensitive materials and the discovery of catalysts for synthesizing fuels and commodity and fine chemicals, respectively. To realize improved electronic properties and enhanced reactivity patterns, the research focuses on new ligand designs that offer tight control over the local coordination environment of the metal ion while also expanding the number of accessible oxidation state available to the metal ion. Collaboration with the SoCal Undergraduate Research Symposium at UCI provides research mentoring and guidance to undergraduate students, many from underrepresented groups, as they prepare to matriculate from graduate degree programs in STEM fields.This project centers on the development of tetradentate, redox-active ligands and the synthesis and characterization of their related transition-metal coordination complexes. The ligand design incorporates an ortho-phenylenediamine backbone that coordinates directly to the metal center and augments metal-based redox process due to its own three oxidation states that are accessible at mild potentials. Additionally, the ligand design incorporates two ancillary “arms” that also bind to the metal ion, providing stability and steric protection at the metal center and offer control over the local coordination environment. These ligand design features are deployed in two thrusts: (a) the development of ligand-to-ligand charge-transfer chromophores and (b) the development of catalysts for multi-electron, atom- and group-transfer reactions. In pursuing this project, the Heyduk group will utilize inorganic synthetic techniques to obtain new molecules for study. New complexes will be characterized by a battery of techniques including electrochemical methods, single crystal X-ray diffraction, NMR, EPR, UV-vis-NIR, and IR spectroscopies, as well as computational methods. Benefits and outcomes of the proposed work include an expanded understanding of how redox-active ligands can be used to control and enhance reactivity at transition metal ions and the training of a workforce skilled in the synthesis, characterization, and utilization of reactive coordination complexes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.