Strong C-H Bond Activation through Superbase Incorporation and pKa Matching

通过超碱结合和 pKa 匹配实现强 C-H 键激活

• 批准号: 2247692
• 负责人: Neil Tomson
• 金额: $ 55万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2247692&HistoricalAwards=false
• 关键词: Strong; Bond; Activation; through; Superbase

With the support of the Chemical Synthesis program in the Division of Chemistry, Neil C. Tomson of the University of Pennsylvania will study the selective cleavage of C–H bonds, a grand challenge in chemistry. These notoriously unreactive bonds are widespread, from fossil fuels to plastics and other materials. The development of methods for splitting C-H bonds in a controlled manner is expected to aid in our fundamental understanding of their reaction chemistry and provide insight into how biological systems can perform these reactions with relative ease. These methods are also expected to enable technological developments, including the use of abundant feedstock chemicals, such as methane, for alternative fuels production. Trainees on this project will become skilled at performing highly air- and moisture-sensitive synthetic chemistry. This work will be supplemented by the use of modern computational chemistry techniques, which will provide an information-rich supplement to the synthetic chemistry being performed in the laboratory. The project will contribute to ongoing outreach efforts aimed at introducing high school students to themes in energy science. This effort will involve the creation of short videos that provide visual aids for explaining important aspects of chemistry in an accessible and captivating manner. The videos will highlight concepts covered within a high school curriculum and dovetail them with the alternative fuels focus of this research project.The activation of aliphatic C–H bonds is challenging for several reasons, including the need for a strong thermodynamic driving force for C–H bond cleavage. Copper ions, in combination with O2, are known to mediate strong C–H bond activation reactions in enzymes, but homogeneous systems have yet to adequately replicate this reactivity. This research seeks to bridge this divide through two complementary objectives. The first will create ligand scaffolds capable of engaging in low-barrier hydrogen bonds with a protonated cupric superoxide unit. The added thermodynamic driving force for proton transfer imparted by these unique hydrogen bonding interactions is expected to boost C–H bond activation reactivity. The second will seek to shift the thermodynamic landscape for proton transfer under anaerobic conditions by introducing superbasic functionalities (pKa of conjugate acid greater than 16) into the primary or secondary coordination spheres of cupric complexes. This latter strategy will be supplemented by the use of machine learning to accelerate the discovery of critical factors controlling the capacity of various ligand systems to enable strong C–H bond activation. The research described in this proposal is aimed at generating the knowledge needed to create new classes of base metal complexes for the efficient and selective activation of low molecular weight alkanes. This work has the potential to advance our understanding of critical C–H bond activation chemistry, while guiding future studies on the catalytic processing of alternative fuels relevant to a renewable energy economy.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.

在化学系的化学合成项目的支持下，尼尔·C。宾夕法尼亚大学的汤姆逊将研究C-H键的选择性断裂，这是化学界的一个巨大挑战。从化石燃料到塑料和其他材料，这些臭名昭著的不活泼的化学键随处可见。 以受控方式分裂C-H键的方法的发展预计将有助于我们对其反应化学的基本理解，并提供对生物系统如何相对容易地进行这些反应的见解。预计这些方法还将促进技术发展，包括利用丰富的原料化学品，如甲烷，生产替代燃料。该项目的学员将熟练掌握高度空气和水分敏感的合成化学。这项工作将通过使用现代计算化学技术来补充，这将为实验室中进行的合成化学提供丰富的信息补充。该项目将有助于正在进行的旨在向高中生介绍能源科学主题的外联工作。这项工作将包括制作短视频，以便于理解和吸引人的方式提供视觉辅助，解释化学的重要方面。这些视频将突出高中课程中涵盖的概念，并将其与本研究项目的替代燃料重点相吻合。脂肪族C-H键的活化具有挑战性，原因有几个，包括C-H键断裂需要强大的热力学驱动力。已知铜离子与O2结合可介导酶中的强C-H键活化反应，但均相系统尚未充分复制这种反应性。本研究试图通过两个互补的目标来弥合这一鸿沟。第一个将创建配体支架，能够与质子化铜超氧化物单元进行低势垒氢键。 由这些独特的氢键相互作用赋予的质子转移的附加热力学驱动力预计将提高C-H键活化反应性。第二个将寻求通过将超碱性功能（共轭酸的pKa大于16）引入到铜络合物的初级或次级配位球中来改变在厌氧条件下质子转移的热力学景观。后一种策略将通过使用机器学习来补充，以加速发现控制各种配体系统能力的关键因素，以实现强C-H键活化。本提案中描述的研究旨在产生创建新类别的贱金属络合物所需的知识，以有效和选择性地活化低分子量烷烃。这项工作有可能促进我们对关键C-H键活化化学的理解，同时指导未来与可再生能源经济相关的替代燃料催化处理研究。该奖项反映了NSF的法定使命，并被认为值得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来支持。