Molecular rotors for studying transition state stabilization by non-covalent interactions

用于研究非共价相互作用过渡态稳定性的分子转子

• 批准号: 2003889
• 负责人: Ken Shimizu
• 金额: $ 44.75万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003889&HistoricalAwards=false
• 关键词: Molecular; rotors; studying; transition; state

Professor Ken D. Shimizu of the University of South Carolina is supported by the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry to investigate the role of non-bonding interactions in the stabilization of the transition state between reactants and products. Catalysts are frequently used to speed up chemical reactions and make them more selective for the desired product. A key challenge in catalysis development is enhancing the ability of catalysts to bring together molecules into crowded reactive structures know as transitions states. Professor Shimizu and his students are constructing molecular machines (rotors) that assist in the fundamental understanding and optimization of catalyst reactivity. The molecular rotors are designed to assess factors that simplify the formation of these crowded reactive structures via changes in the speed of their rotation. Thus, the molecular rotors provide a simple and systemic way to study and improve catalyst design. The development of new and improved catalysts enables the efficient production of new chemicals, polymers, fuels, and pharmaceuticals. Graduate and undergraduate students are trained in research methods, in particular women chemists through a collaboration with faculty and students at a local women’s college. A graduate course is developed to provide students with fundamental skills, such as how to present seminars, time and research management strategies, and how to write research publications and proposals. The ability of non-covalent interactions to stabilize transition states is measured using a series of molecular rotors. The rotors form non-covalent interactions in their planar transition states. The stabilizing effects of the non-covalent interactions can be measured from the increase in speed of the molecular rotors. The versatility and modularity of the rotor framework enables the study of a wide range of non-covalent interactions including hydrogen bonds, cation-pi, anion-pi, n-pi*, chalcogen-chalcogen, CH-pi, arene-arene, OH-pi, and metal-pi interactions. The transition state effects are easily and accurately assessed by measuring the rotational barriers using dynamic NMR spectroscopy. Finally, the rigid framework limits the degrees of freedom in the ground and transition states enabling accurate modeling and simulation using standard DFT methods, which provide computational-corroboration of the experimentally measured barriers, transition state structures, and insights into the origins of the stabilizing effects. The project broadly impacts the development of new strategies to improve synthetic catalysts and provides insights into the large rate accelerations in enzymatic systems. In addition, the development of a new strategy for studying and interrogating transition state energies using molecular rotors provides chemists with new tools for fundamental kinetic studies.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.

Ken D.南卡罗来纳州大学的Shimizu得到化学系大分子、超分子和纳米化学项目的支持，研究非键相互作用在反应物和产物之间过渡态稳定中的作用。 催化剂通常用于加速化学反应，使其对所需产物更具选择性。催化剂发展的一个关键挑战是提高催化剂的能力，使分子聚集成拥挤的反应结构，称为过渡态。 清水教授和他的学生正在建造分子机器（转子），以帮助对催化剂反应性的基本理解和优化。 分子转子被设计成通过改变其旋转速度来评估简化这些拥挤的反应结构的形成的因素。 因此，分子转子为研究和改进催化剂设计提供了一种简单而系统的方法。 新的和改进的催化剂的开发能够高效生产新的化学品、聚合物、燃料和药品。 研究生和本科生接受研究方法培训，特别是通过与当地女子学院的教师和学生合作，对女化学家进行培训。一个研究生课程的开发，为学生提供基本技能，如如何提出研讨会，时间和研究管理策略，以及如何写研究出版物和建议。 使用一系列分子转子测量非共价相互作用稳定过渡态的能力。 转子在其平面过渡态中形成非共价相互作用。 非共价相互作用的稳定作用可以从分子转子速度的增加来测量。 转子框架的多功能性和模块化使得能够研究广泛的非共价相互作用，包括氢键、阳离子-π、阴离子-π、n-pi *、硫族元素-硫族元素、CH-π、芳烃-芳烃、OH-π和金属-π相互作用。过渡态的影响是很容易和准确地评估通过测量的旋转障碍，使用动态NMR光谱。 最后，刚性框架限制了基态和过渡态的自由度，从而能够使用标准DFT方法进行准确的建模和模拟，该方法提供了实验测量的屏障、过渡态结构的计算确证，并深入了解了稳定效应的起源。 该项目广泛影响了改进合成催化剂的新策略的开发，并提供了对酶系统中大速率加速的见解。 此外，利用分子转子研究和询问过渡态能量的新策略的开发为化学家提供了基础动力学研究的新工具。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进行评估，被认为值得支持。

项目成果

Pnictogen Interactions with Nitrogen Acceptors

氮元素与氮受体的相互作用

• DOI: 10.1002/anie.202304960
• 发表时间: 2023
• 期刊: Angewandte Chemie International Edition
• 作者: Lin, Binzhou;Liu, Hao;Karki, Ishwor;Vik, Erik C.;Smith, Mark D.;Pellechia, Perry J.;Shimizu, Ken D.
• 通讯作者: Shimizu, Ken D.

Electrostatically-gated molecular rotors

静电门控分子转子

• DOI: 10.1039/d2cc00512c
• 发表时间: 2022
• 期刊: Chemical Communications
• 影响因子: 4.9
• 作者: Lin, Binzhou;Karki, Ishwor;Pellechia, Perry J.;Shimizu, Ken D.
• 通讯作者: Shimizu, Ken D.