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

在化学系化学合成计划的资助下，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，以在过渡金属离子的配位络合物中产生更好的电子性质和增强的反应模式。该项目的动机是，配位络合物的电子性质和反应模式在不同的研究领域发挥着关键作用，例如开发新的光敏材料，发现分别用于合成燃料、商品和精细化学品的催化剂。为了实现更好的电子性质和增强的反应模式，研究重点放在新的配体设计上，这种设计可以严格控制金属离子的局部配位环境，同时也增加了金属离子可访问的氧化态的数量。与UCI的SoCal本科生研究研讨会合作，为准备从STEM领域的研究生课程入学的本科生提供研究指导和指导，其中许多来自代表不足的群体。该项目集中在四齿、氧化还原活性配体的开发及其相关过渡金属配位化合物的合成和表征。配体设计结合了直接与金属中心配位的邻苯二胺主链，并由于其自身的三个氧化态在温和的电位下可访问而增强了基于金属的氧化还原过程。此外，配基设计还包括两个辅助“臂”，它们也与金属离子结合，在金属中心提供稳定性和空间位阻保护，并提供对局部配位环境的控制。这些配体的设计特点体现在两个方面：(A)开发配体到配体的电荷转移发色团和(B)开发用于多电子、原子和基团转移反应的催化剂。在进行这一项目时，Heyduk小组将利用无机合成技术来获得用于研究的新分子。新的配合物将通过一系列技术进行表征，包括电化学方法、单晶X射线衍射、核磁共振、EPR、UV-VIS-NIR和IR光谱以及计算方法。拟议工作的好处和成果包括扩大了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，以及培训了一支熟练于反应配位络合物的合成、表征和利用的劳动力。该奖项反映了NSF的法定使命，并通过使用基金会的智力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.