Tunable Masks for Triggered N-heterocyclic Carbene Organocatalysis

用于触发 N-杂环卡宾有机催化的可调掩模

• 批准号: 2154633
• 负责人: Jessica Lamb
• 金额: $ 50万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2154633&HistoricalAwards=false
• 关键词: Tunable; Masks; Triggered; heterocyclic; Carbene

With the support of the Chemical Structure, Dynamics, and Mechanisms B (CSDM-B) program in the Division of Chemistry, Jessica Lamb of the University of Minnesota is studying a new way to control chemical reactivity via catalysis. Because of their wide utility, N-heterocyclic carbenes (NHCs) are a particularly important class of catalysts that has garnered a lot of attention in the past few decades. NHCs are sensitive compounds that can degrade if exposed directly to air or moisture; therefore, small molecules can be used to hide, or “mask”, the NHC reactivity until heat or light is used to release the NHC catalyst at the desired time. Despite extensive work in this area, little is known about how changing the small molecule “mask” can tune the exact conditions under which the NHC will release. The Lamb group will explore new mask structures that will be used to systematically study how changes in the mask will alter the catalytic behavior of the NHCs. The work has broad implications for designing new releasable catalysts, catalyst recycling, and polymer synthesis in the future. The project lies at the intersection of catalysis, polymer, and physical organic chemistry and thus will provide excellent interdisciplinary training and education to the supported graduate and undergraduate students. The Lamb group is composed of a diverse group of scientists who are actively engaged in outreach activities focused on recruiting and retaining underrepresented scholars in the STEM (science, technology, engineering and mathematics) fields.Latent/switchable catalysis uses external stimuli to control when and where chemical reactions take place. N-Heterocyclic carbenes (NHCs) are powerful, tunable organocatalysts, but their sensitivity to air and moisture often necessitates the use of latent catalysis through the use of “masked” NHCs. Current masked NHC systems are limited because the adduct bond strength is controlled by the structure of the NHC, leading to a trade-off between latency and activity of the catalyst. This project will investigate fundamental structure-property relationships that dictate NHC adduct bond stability and release by changing the mask, not the catalyst, structure. Specifically, the Lamb group will investigate carbodiimides and triarylboranes as modular mask scaffolds that can be activated using heat or light as the external stimulus. This work will apply physical organic techniques to understand and predict structure-property relationships first between mask structure and adduct stability then further correlate that stability to catalyst activity. The work will have societal impact in terms of education of undergraduate and graduate students – including students from underrepresented groups – publication of research that increases fundamental chemical knowledge, and through supporting Dr. Lamb’s outreach activities focused on recruiting and retaining underrepresented scholars in chemistry.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.

在化学系化学结构、动力学和机理B（CSDM-B）项目的支持下，明尼苏达大学的杰西卡·兰姆正在研究一种通过催化控制化学反应性的新方法。 由于其广泛的用途，N-杂环卡宾（NHC）是一类特别重要的催化剂，在过去的几十年里引起了人们的广泛关注。NHC是敏感的化合物，如果直接暴露于空气或水分，则可以降解;因此，小分子可以用于隐藏或“掩蔽”NHC反应性，直到在期望的时间使用热或光来释放NHC催化剂。尽管在这一领域进行了大量的工作，但人们对如何改变小分子“掩模”可以调整NHC释放的确切条件知之甚少。Lamb小组将探索新的掩模结构，用于系统地研究掩模的变化如何改变NHC的催化行为。这项工作对设计新的可释放催化剂，催化剂回收利用和未来的聚合物合成具有广泛的意义。该项目位于催化，聚合物和物理有机化学的交叉点，因此将为支持的研究生和本科生提供优秀的跨学科培训和教育。Lamb小组由一群多元化的科学家组成，他们积极参与外联活动，专注于招募和留住STEM（科学、技术、工程和数学）领域代表性不足的学者。潜在/可切换催化利用外部刺激来控制化学反应发生的时间和地点。N-杂环卡宾（NHC）是强大的、可调的有机催化剂，但它们对空气和水分的敏感性通常需要通过使用“掩蔽的”NHC来使用潜在催化。目前掩蔽的NHC系统是有限的，因为加合物键强度由NHC的结构控制，导致催化剂的潜伏期和活性之间的权衡。本项目将研究基本的结构-性质关系，决定NHC加合键的稳定性和释放通过改变掩模，而不是催化剂，结构。具体来说，兰姆小组将研究聚酰亚胺和三芳基硼烷作为模块化掩模支架，可以使用热或光作为外部刺激来激活。这项工作将应用物理有机技术来理解和预测掩模结构和加合物稳定性之间的结构-性质关系，然后进一步将该稳定性与催化剂活性相关联。这项工作将在本科生和研究生的教育方面产生社会影响-包括来自代表性不足群体的学生-发表增加基础化学知识的研究，Lamb博士的推广活动，重点是招募和留住化学领域代表性不足的学者。该奖项反映了NSF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。