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，南卡罗来纳州大学的唐传兵教授和斯蒂芬·L.杜克大学的克雷格将开发一类含金属的聚合物，它们在机械应力下会发生化学变化。家用塑料制造中的普通技术可以被修改以制备这些聚合物。 机械应力是聚合物所经历的环境中几乎普遍存在的特征。将机械应力转化为响应性化学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，这两者对于大多数商品聚合物的可重复使用性和可回收性都很重要。 这项工作的影响将通过与高中，本科和研究生水平的新的和现有的外展计划和教育活动的紧密结合而进一步扩大。这些计划通过与美国化学学会项目种子夏季研究计划，ACS聚合物学生分会和当地历史上的黑人学院和大学的合作伙伴关系而得到丰富。联合研究交流将提供给参与UofSC和杜克的学生，以增强他们的研究经验，扩大未来的职业道路。 本项目的重点是开发合成方法，以主链含异戊二烯的聚合物和研究其机械化学反应性。 茂金属最近作为一类新的机械载体出现。该研究旨在巩固不断发展的机械化学知识，并通过使用合成茂金属化学和聚合物机械化学的合作努力将其扩展到新的研究前沿。将通过形成半夹心金属配合物来探索C-H官能化和氧化还原异构化的催化化学。茂金属机械载体的敏化作用将进一步实现在茂金属大环化合物中，通过结合远端构象锁和反式辅助，并通过单分子力谱定量它们对反应性的相互作用。重要的是，建设性的机械化学将追求通过使用重建过程，使活化的双烯可逆，并通过采用DFT计算来阐明解离状态和三明治结构之间的热力学平衡。这项工作的总体目标是了解金属-金属键的高选择性机械化学断裂的机制和结构-活性关系。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。

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.