Collaborative Research: CAS: Mechanochemistry of Metallocenes

在化学系大分子、超分子和纳米化学项目的支持下，南卡罗来纳大学(UofSC)的唐传兵教授和杜克大学的Stephen L.Craig教授将开发一种在机械应力下响应化学变化的含金属聚合物。家用塑料制造中的常见技术可以被改进以制备这些聚合物。机械应力是聚合物环境中几乎无处不在的特征。机械应力到响应化学的转化可能为开辟催化和先进材料等应用提供新的途径。这项工作有可能开发出机械响应和热稳定的合成聚合物，这两者对大多数商品聚合物的可重复使用和可回收利用都很重要。这项工作的影响将通过与新的和现有的外展计划以及高中、本科生和研究生层面的教育活动的密切结合而进一步扩大。这些项目通过与美国化学协会项目种子暑期研究项目、ACS聚合物学生分会以及当地历史上的黑人学院和大学的合作而得到丰富。南加州大学和杜克大学将为参与研究的学生提供联合研究交流，以增强他们的研究经验，拓展未来的职业道路。本项目致力于开发主链茂金属聚合物的合成方法，并研究其机械力化学反应活性。茂金属最近已成为一类新的机械载体。这项研究旨在巩固机械力化学的不断发展的知识，并通过使用合成茂金属化学和聚合物机械力化学的合作努力，将其扩展到新的研究前沿。通过形成半夹心金属络合物，探索C-H官能化和氧化还原异构化的催化化学。通过将远端构象锁定和反离子辅助结合起来，并通过单分子力谱来量化它们对反应活性的相互作用，茂金属机械团的敏化将在茂金属大环中进一步实现。重要的是，构造性机械力化学将通过使用重构过程使茂金属的活化可逆，并通过使用密度泛函计算来阐明解离态和夹心结构之间的热力学平衡。这项工作的首要目标是了解金属-环戊二烯基键高选择性机械力化学断裂背后的机制和结构-活性关系。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Chuanbing Tang of the University of South Carolina (UofSC) and Professor Stephen L. Craig of Duke University will develop a class of metal-containing polymers that respond with chemical changes under mechanical stress. Common techniques in the manufacturing of household plastics can be modified to prepare these polymers. Mechanical stress is a nearly ubiquitous feature of the environment experience by polymers. The translation of mechanical stress to responsive chemistry may provide new pathways to open up applications such as catalysis and advanced materials. This work has the potential to develop synthetic polymers that are mechanically responsive and thermally stable, both of which are important for reusability and recyclability of most commodity polymers. The impact of this work will be further broadened through its close integration with both new and existing outreach programs and educational activities at the high school, undergraduate, and graduate student level. These programs are enriched by partnerships with American Chemical Society Project SEED summer research program, ACS polymer student chapter, and local Historically Black Colleges and Universities. Joint research exchanges will be offered to participating students at UofSC and Duke to enhance their research experiences and expand future career paths. This project is focused on developing synthetic approaches toward main-chain metallocene-containing polymers and studying their mechanochemical reactivity. Metallocenes have recently emerged as a new class of mechanophores. The research aims to consolidate the evolving knowledge of mechanochemistry and expand it to new frontiers of research through the collaborative efforts using synthetic metallocene chemistry and polymer mechanochemistry. Catalytic chemistry will be explored for C-H functionalization and redox isomerization via the formation half-sandwich metal complexes. Sensitization of metallocene mechanophores will be further achieved in metallocenophane macrocycles by combining distal conformational locks and counterion assistance and quantifying their interplay on reactivity through single molecule force spectroscopy. Importantly, constructive mechanochemistry will be pursued by using reconstructive processes to make the activation of metallocenes reversible and by employing DFT calculations to elucidate thermodynamic equilibria between dissociated states and sandwich constructs. The overarching goal of this work is to understand the mechanisms and structure-activity relationships underlying the highly selective mechanochemical scission of metal-cyclopentadienyl bond.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.