The Role of Non-covalent Interactions in the Excited State Dynamics of Heterocyclic Compounds.

在这个由化学部门化学结构动力学和机制A （CSDM-A）项目资助的项目中，加州大学圣巴巴拉分校的de Vries教授将研究杂环化合物对紫外线（UV）辐射的反应。这些化合物构成了DNA碱基和许多其他重要分子的基本结构，它们对光的反应在许多实际过程中起着重要作用。例如，紫外线吸收后的光化学反应是辐射诱导DNA损伤的基本步骤。紫外线的光选择可能在早期地球的生命前化学中起着关键作用。这些相同的过程也适用于各种现代材料。这些主题与尖端的激光和计算技术相结合，有助于开展以这项工作为基础的推广活动。本科生和研究生都将接受设计和建造先进实验仪器、复杂计算机模拟和进行基础研究的培训。这项工作将与HBCU的杰克逊州立大学的科学家合作进行。德弗里斯教授和他的团队成员将在各种旨在扩大代表性不足群体成员参与STEM的项目中担任导师。紫外线辐射的精确效果主要取决于分子结构，基本光化学受与其他分子相互作用的影响。UCSB de Vries教授的实验室将通过气相光谱实验研究杂环化合物及其簇的基本光性质，并与计算化学家合作，将结果与量子化学模型进行比较。实验将研究π -堆叠和氢键如何影响杂环化合物的激发态势能景观，以及如何改变光化学结果。该项目将在皮秒和纳秒的时间域研究这些分子系统，并用高水平的量子计算对结果进行建模。该奖项反映了美国国家科学基金会的法定使命，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。

In this project, funded by the Chemical Structure Dynamics and Mechanisms A (CSDM-A) program of the Chemistry Division, Professor de Vries at the University of California Santa Barbara will study how heterocyclic compounds respond to exposure to ultraviolet (UV) radiation. Such compounds form the basic structure of DNA bases as well as many other important molecules and their response to light plays a role in many practical processes. For example, the photochemistry following UV absorption constitutes a fundamental step in radiation-induced DNA damage. UV photo-selection may have played a key role in prebiotic chemistry on an early earth. These same processes also find applications in a variety of modern materials. These topics, in combination with cutting-edge laser and computational techniques, lend themselves to outreach activities that will be based on this work. Both undergraduate and graduate students will receive training in the design and construction of advanced experimental instrumentation, complex computer simulation, and conducting fundamental research. This work will be carried out in collaboration with scientists at Jackson State University, an HBCU. Professor De Vries and members of his group will serve as mentors in various programs aimed at broadening participation of members of underrepresented groups in STEM. The precise effects of UV radiation depend critically on molecular structure and the fundamental photochemistry is affected by interactions with other molecules. The laboratory of Professor de Vries at UCSB will study fundamental photoproperties of heterocyclic compounds and clusters containing them experimentally by gas phase spectroscopy and collaborate with computational chemists to compare the results with quantum chemical modeling. The experiments will investigate how pi-stacking and hydrogen bonding affect the excited state potential energy landscape of heterocyclic compounds and how that changes the photochemical outcomes. The project will study these molecular systems in the picosecond and nanosecond time domains and model the results with high level quantum computations.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.