Dynamic Processes in Annulenes

本文提出的量子化学研究集中在[4n]-和[4n+2]环烯的动态过程机制上，包括构象变化、价异构化、键移动和构型变化。通过结合DFT、耦合簇理论和多构型量子力学方法，将确定这些过程的详细机制。将计算得到的能垒与实测的能垒进行比较。对环烯构型变化的扭耦合键转移机制范围的研究，将使我们能够详细比较Mobius、闭壳与平面、开壳键转移在[12]-和[16]环烯等体系中的情况。这将提供有关影响这些进程的障碍因素的信息。此外，还将研究[4n+2]环烯（如[10]-和[14]-）和[4n]环烯（如[12]-）中的非平面键移动。这种键移过渡态将在闭壳体系和单线态双自由基中进行研究。本研究将建立扭转耦合键转移作为环烯化学的基本机制，并证实母环烯中存在莫比乌斯芳香性。它还将阐明较大的[4n]环烯的平面、键均衡形式的双自由基性质和反芳性的程度，并将使鉴定新的莫比乌斯芳香物种和新的环烯异构体成为可行的合成目标。更广泛的影响。因为这个项目借鉴了学生在有机化学大二所学到的基本概念——芳香性、分子轨道理论、哈克规则和周环反应——这是一个让学生参与研究的绝佳机会。考虑到旧金山大学的学生人数，在科学领域培养代表性不足的群体的成员，特别是女性和西班牙裔学生，具有特别的潜力。学生将获得各种计算技术的经验，此外，他们将学习如何处理一个研究项目，从搜索文献和提出问题，到展示和发表工作。在卡斯特罗-卡尼研究小组工作过的大多数本科生都继续（或正在申请）在其他机构攻读高级学位。这里概述的项目将通过为学生提供培训来增强网络基础设施，这些学生将成为应用量子力学解决化学问题的未来专家。

The quantum chemical study proposed here focuses on the mechanisms of the dynamic processes in [4n]- and [4n+2]annulenes which include conformational changes, valence isomerizations, bond shifting, and configuration changes. By employing a combination of DFT, coupled cluster theory, and multi-configurational quantum mechanical methods, detailed mechanisms for these processes will be determined. The computed energy barriers will be compared with measured ones. Investigation of the scope of twist-coupled bond shifting mechanism for configuration change in annulenes will enable a detailed comparison of Mobius, closed-shell vs. planar, open-shell bond shifting in systems such as [12]- and [16]annulene. This will provide information regarding factors influencing the barriers for these processes. In addition, non-planar bond shifting in [4n+2]annulenes (e.g. [10]- and [14]-) and [4n]annulenes (e.g. [12]-) will be examined. This bond-shifting transition states will be studied in both closed-shell systems and singlet diradicals. This work will establish twist-coupled bond shifting as a fundamental mechanism in annulene chemistry and confirm that Mobius aromaticity exists in parent annulenes. It will also clarify the diradical nature and degree of antiaromatic character of planar, bond-equalized forms of larger [4n]annulenes and will enable the identification of new Mobius aromatic species as well as new annulene isomers that are viable synthetic targets.Broader Impacts. Because this project draws on fundamental concepts that students learn in sophomore organic chemistry-aromaticity, molecular orbital theory, the Huckel rule, and pericyclic reactions-it represents an excellent opportunity to engage students in research. Given the student population at the University of San Francisco, there is particular potential for training members of under-represented groups in science, especially women and Hispanic students. Students will gain experience in a wide variety of computational techniques and, in addition, they will learn how to approach a research project, from searching the literature and formulating questions, to presenting and publishing the work. The majority of undergraduates who have worked in the Castro-Karney research group have gone on to (or are applying to) pursue advanced degrees at other institutions. The project outlined here will enhance cyberinfrastructure by providing training for students who will be future experts in the application of quantum mechanics to the solution of chemical problems.