Visible Light and Divalent Lanthanides in Photoredox Catalysis

光氧化还原催化中的可见光和二价镧系元素

• 批准号: 1564755
• 负责人: Matthew Allen
• 金额: $ 40.5万
• 依托单位: Wayne State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-15 至 2020-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1564755&HistoricalAwards=false
• 关键词: Visible; Light; Divalent; Lanthanides; Photoredox

In this project funded by the Chemical Catalysis program of the Chemistry Division, Professor Matthew J. Allen, Chemistry Department, Wayne State University, is studying new lanthanide systems that catalytically perform reductions and bond-forming reactions when exposed to visible light. Catalysts are substances that permit chemical reactions to be run rapidly with minimum energy consumption. They are used in a variety of industrial processes. In this project, catalysts are being developed that utilize and can be switched on and off by visible light. In addition, they operate under conditions that are not compatible with current catalysts. Several important processes including reactions that form carbon-carbon bonds are studied. Graduate, undergraduate, and high school students are trained to become skilled and ethical scientists. High school students, who are from groups underrepresented in science, have an opportunity to participate in research, leading to a more educated and diverse scientific workforce.This project focuses on new lanthanide-containing complexes that can drive visible-light-promoted photoredox catalysis. Specifically, the project tests the hypothesis that if trivalent lanthanide-containing azacryptates are exposed to a sacrificial reductant and visible light, they perform catalysis at redox potentials more negative than divalent lanthanide salts alone. Testing this hypothesis simultaneously addresses two long-standing challenges in redox chemistry: (1) the need for photoredox catalyts tunable across a range of potentials and wavelengths for improved chemoselectivity and (2) the need for air-stable, non-toxic alternatives to samarium(II) hexamethyl phosphoramide. The research includes the synthesis of a series of complexes of divalent and trivalent europium and ytterbium. These complexes are characterized by UV/visible and fluorescence spectra, electrochemical potentials, thermodynamic and kinetic stabilities, crystal structures, solubilities, and propensities for transmetallation. Additionally, the complexes are studied with respect to their ability to catalyze important classes of photoredox reactions including reductions, carbon-carbon bond formations, and ring closures. Finally, students are trained in the scientific method and the responsible conduct of research.

在这个由化学部化学催化项目资助的项目中，韦恩州立大学化学系的 Matthew J. Allen 教授正在研究新的镧系元素系统，该系统在暴露于可见光时催化进行还原和成键反应。催化剂是允许化学反应以最小的能量消耗快速进行的物质。它们用于各种工业过程。在这个项目中，正在开发利用可见光并可以通过可见光打开和关闭的催化剂。此外，它们的运行条件与现有催化剂不兼容。研究了包括形成碳-碳键的反应在内的几个重要过程。研究生、本科生和高中生接受培训，成为熟练且有道德的科学家。来自科学领域代表性不足的群体的高中生有机会参与研究，从而培养受过更多教育、更加多样化的科学队伍。该项目重点研究可以驱动可见光促进的光氧化还原催化的新型含镧系元素络合物。具体来说，该项目测试了这样的假设：如果含有三价镧系元素的氮杂穴状化合物暴露于牺牲还原剂和可见光，它们会在比单独的二价镧系元素盐更负的氧化还原电位下进行催化。测试这一假设同时解决了氧化还原化学中两个长期存在的挑战：(1) 需要在一系列电势和波长范围内可调的光氧化还原催化剂，以提高化学选择性；(2) 需要空气稳定、无毒的钐替代品(II)六甲基磷酰胺。该研究包括一系列二价和三价铕和镱络合物的合成。这些配合物的特征在于紫外/可见光和荧光光谱、电化学势、热力学和动力学稳定性、晶体结构、溶解度和金属转移倾向。此外，还研究了这些配合物催化重要类别光氧化还原反应的能力，包括还原、碳-碳键形成和闭环。最后，学生接受科学方法和负责任的研究行为方面的培训。