Tuning Teflon-Coated Earth-Abundant Metal Complexes in Oxidative Catalysis

在化学系化学催化项目的支持下，波士顿大学的Linda Doerrer教授和罗克斯伯里社区学院的Kimberly Ann Stieglitz教授将研究碳氢键转化为碳氧键和碳碳键的具体过程。这些氧化反应是现代化学中广泛而关键的反应。最便宜和最可持续的氧化剂是大气氧（O2），但氧也能够氧化失活许多催化剂系统。几乎所有在这些氧化反应中利用O2的催化剂都含有使这些反应发生的过渡金属。这项工作将扩大目前的努力，以制备由富氟“特氟龙涂层”配体系统支持的新型Cu催化剂，为分子催化剂提供稳定性。研究人员将制备新的化合物，其中夹紧配体将金属原子紧紧地夹住，以控制O2与底物之间的反应性。该项目还将探索除Cu外使用其他金属的氧化，特别是Mn和V，并将研究扩展到含铁系统。一个重要的推动力将是开发在水和空气中表现良好的催化剂，使这些碳氢化合物氧化系统更加可持续和环保。这项工作的广泛影响将涉及本科课程开发、学生培训以及波士顿大学和罗克斯伯里社区学院之间的富有成效的合作。罗克斯伯里社区学院（Roxbury Community College）的学生中，有很大一部分来自得不到充分教育的少数群体；因此，这一合作努力将旨在增加STEM（科学、技术、工程和数学）领域的多样性、公平性和包容性。在这些研究中，波士顿大学的Linda Doerrer教授和罗克斯伯里社区学院的Kimberly Ann Stieglitz教授将研究碳氢键的氧化。这项工作建立在研究人员先前对Cu/O2化学的研究基础上，该研究已经证明了氟化醇氧配体在生成氧化C-H键的高活性物质方面的有效性。研究了氧化还原惰性阳离子（特别是K）的性质和包封程度对催化活性的影响。Li, Na， Rb和Cs的其他反阳离子也将被追求，以及铁基催化剂体系，将通过两个互补的途径获得。一个波德威尔方阵方法将被用来原地生成一个提议的{Mn(III)OH}试剂，该试剂将被用来探测其热力学性质。该团队将在罗克斯伯里社区学院（Roxbury Community College）教授一门动手实验合成和光谱学课程，探索能够催化C-H键氧化的稳定钒化合物的反应范围和优化反应条件。这种持续的合作汇集了过渡金属配合物（Doerrer）和有机化合物表征（Stieglitz）方面的专业知识，并将加强对代表性不足的少数民族学生的STEM职业培训，同时让他们在R1大学进行研究。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 the support of the Chemical Catalysis program in the Division of Chemistry, Professor Linda Doerrer of Boston University and Professor Kimberly Ann Stieglitz of Roxbury Community College will study the specific conversion of carbon-hydrogen bonds to carbon-oxygen and carbon-carbon bonds. These oxidation reactions are widespread and critical reactions in modern chemistry. The cheapest and most sustainable oxidant is atmospheric oxygen (O2) but oxygen also is capable of oxidatively inactivating many catalyst systems. Almost all catalysts that utilize O2 in these oxidation reactions contain transition metals that enable these reactions to take place. This work will expand on current efforts to prepare new Cu catalysts supported by fluorine-rich “Teflon-coated” ligand systems that provide stability to the molecular catalysts. The researchers will prepare new compounds in which clamping ligands hold metal atoms tightly to control reactivity between O2 and the substrate. The project will also probe oxidations using other metals besides Cu, particularly with Mn and V, and will extend the research to Fe-containing systems. An important thrust will be the development of catalysts that perform well in water and air to make these hydrocarbon oxidation systems more sustainable and environmentally friendly. The broader impacts of this work will involve undergraduate course development, student training, and a productive collaboration between Boston University and Roxbury Community College. Roxbury Community College delivers instruction to a high percentage of students from underserved minority groups; thus this collaborative effort will be directed at increasing diversity, equity, and inclusion in STEM (science, technology, engineering and mathematics) fields. In these studies, Professors Linda Doerrer of Boston University and Kimberly Ann Stieglitz of Roxbury Community College will study the oxidation of C-H bonds. This work builds on prior work of the researchers on Cu/O2 chemistry that has demonstrated the effectiveness of fluorinated alkoxide ligands to make highly reactive species for oxidizing C-H bonds. The nature and degree of encapsulation of redox inert counter cations, specifically K, on the catalytic activity will be investigated. Other counter cations of Li, Na, Rb, and Cs will also be pursued, as will an Fe-based catalysts system which will be accessed via two complementary routes. A Bordwell square approach will be used to generate a proposed {Mn(III)OH} reagent in situ that will be used to probe its thermodynamic properties. Exploration of the scope and optimization of reaction conditions with a benchtop-stable vanadium compound capable of catalytic C-H bond oxidation will be part of a hands-on experimental synthesis and spectroscopy class taught at Roxbury Community College by the collaborative team. This continued collaboration brings together expertise in transition metal complexes (Doerrer) and in organic compound characterization (Stieglitz), and will enhance the training of underrepresented minority students for STEM careers while exposing them to research at an R1 university.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.