RUI: Heavy-Atom Tunneling in Annulenes and Helical Polycyclic Conjugated Hydrocarbons

有了这个奖项，美国国家科学基金会化学部的化学结构，动力学和机制计划正在支持教授威廉·卡尼和他的本科生研究团队在化学系在旧金山弗朗西斯科的大学，探索量子力学隧道的程度由重原子在有机分子的反应。该项目结合了实验和理论，将有助于基本了解什么类型的化学反应是通过屏障而不是越过屏障进行的。穿过势垒的通道被称为量子力学隧道。 待研究的系统包括具有分子开关潜力的化合物，以及与有机合成和生物化学相关的反应。该项目的学生将获得合成，光谱学和广泛的计算化学方法的经验。南佛罗里达大学的学生群体高度多样化，这意味着培养科学领域代表性不足的群体成员的潜力很大，特别是女性，拉丁裔学生和来自太平洋沿岸的学生。尽管碳的原子质量相对于氢来说很大，但如果碳原子只有很短的距离，它们可以在化学反应中穿过障碍。本计画结合实验与计算来研究轮烯与多环共轭碳氢化合物中的重原子隧穿现象。低温核磁共振光谱将探测[16]轮烯平面π键位移中所有16个碳的可能隧穿。本文将通过多维隧道计算来研究几种轮烯中的跨环电环闭合反应，以探索隧道在周环反应中的作用范围。螺旋多环共轭烃的轨道对称禁止的电环化，系统的潜在用途作为手性光开关，将计算研究，重点是隧道和对称性降低由于激发态混合。这项工作旨在加深我们对重原子隧穿的理解，并拓宽研究隧穿起主要作用的反应的范围。该项目还将为本科生提供合成、光谱学和高级计算技术方面的培训，并包括与当地中学生的外联活动，使他们接触计算化学。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。

With this award, the Chemical Structure, Dynamics and Mechanism Program of the NSF Chemistry Division is supporting Professor William Karney and his undergraduate research team in the Department of Chemistry at the University of San Francisco to explore the extent of quantum mechanical tunneling by heavy atoms in reactions of organic molecules. The project combines experiment and theory, and will contribute to a basic understanding of what types of chemical reactions proceed by passage through a barrier rather than over the barrier. Passage through the barrier is known as quantum mechanical tunneling. Systems to be studied include compounds with potential as molecular switches, and reactions relevant to organic synthesis and biochemistry. Students on the project will gain experience in synthesis, spectroscopy, and a wide range of computational chemistry methods. The highly diverse student population at USF translates to high potential for training members of underrepresented groups in science, especially women, Latinx students, and those from the Pacific Rim.Despite the large atomic mass of carbon relative to hydrogen, carbon atoms can tunnel through barriers in chemical reactions if they travel only short distances. This project combines experiment and computations to investigate heavy-atom tunneling in annulenes and polycyclic conjugated hydrocarbons. Low-temperature nuclear magnetic resonance spectroscopy will probe possible tunneling by all 16 carbons in the planar pi-bond shifting of [16]annulene. Transannular electrocyclic ring closures in several annulenes will be studied by multidimensional tunneling calculations to explore the scope of tunneling in pericyclic reactions. Orbital-symmetry forbidden electrocyclizations of helical polycyclic conjugated hydrocarbons, systems of potential use as chiroptical switches, will be computationally investigated, with a focus on tunneling and symmetry lowering due to excited-state mixing. The work seeks to deepen our understanding of heavy-atom tunneling and to broaden the scope of reactions studied in which tunneling plays a major role. The project also will provide training in synthesis, spectroscopy, and high-level computational techniques for undergraduates and includes outreach activities with local middle school students to expose them to computational 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.