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 Jessica Lamb 正在研究一种通过催化控制化学反应性的新方法，因为其用途广泛。 N-杂环卡宾 (NHC) 是一类特别重要的催化剂，在过去几十年中引起了广泛关注，NHC 是敏感化合物，如果直接暴露于空气或湿气中，就会发生降解。分子可用于隐藏或“掩盖”NHC 反应性，直到在所需时间使用热或光释放 NHC 催化剂，尽管在这一领域进行了大量工作，但人们对如何改变小分子“掩盖”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，这项工作对于设计新的可释放物质具有广泛的意义。催化剂，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。积极从事外展活动的科学家群体，致力于招募和留住 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。杂环卡宾 (NHC) 是强大的、可调节的有机催化剂，但它们对空气和水分的敏感性通常需要通过使用“掩蔽”NHC 来使用潜在催化作用，因为加合物键合强度受其结构控制。 NHC，导致催化剂的潜伏期和活性之间的权衡，该项目将研究决定 NHC 加合物键稳定性和通过改变掩模释放的基本结构-性质关系，具体来说，Lamb 小组将碳二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，这项工作将首先应用物理有机技术来理解和预测之间的结构-性能关系。掩模结构和加合物稳定性，然后进一步将稳定性与催化剂活性联系起来，这项工作将对本科生和研究生（包括来自代表性不足群体的学生）的教育产生社会影响，发表增加基础化学知识的研究，并通过支持博士。羔羊的外展该奖项反映了 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。