Theoretical and Experimental Investigations of Photoheterolysis Reactions

通过这个奖项，化学结构动力学和机理- b项目支持由爱荷华州立大学的Arthur Winter进行的光化学领域的基础研究。分子对光的吸收会导致化学键断裂，但通常很难理解特定化学键断裂的原因或方式。温特博士和他的学生试图理解一种一般类型的键裂解的结构-反应性原理，特别是碳和离去基之间的键的光化学异裂。异解反应是化学键断裂的一种可能方式，化学键中的两个电子都被给予其中一个脱离的基团。光异解反应在生物学、材料科学和环境化学中具有重要意义。该项目的长期目标是建立一个预测的理论框架，将化学结构与激发态反应性联系起来，从而为指导光化学反应提供新的指导机制原理。在更广泛的影响活动中，温特教授还将参与一项新生研究计划，该计划让一年级大学生参与早期多学科研究经验。他还将继续从代表性不足的群体中招募本科生和学生到他的实验室。为了研究这些光异解反应，PI将采用理论/实验相结合的方法。高级计算方法将用于映射激发态过渡态和模型系统的表面交叉拓扑。实验上，光谱学将确定结构对模型系统中光释放速率和机制的影响。特别是，超快飞秒分辨瞬态吸收光谱将用于确定在所选底物上光异解反应的速率和机制，而高能级激发态计算将用于提供机制基础。这项研究将为本科生和研究生提供广泛的培训。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。

With this award, the Chemical Structure Dynamics and Mechanisms-B program is supporting fundamental research in the field of photochemistry, carried out by Arthur Winter at Iowa State University. The absorption of light by molecules can lead to cleavage of chemical bonds but it is often difficult to understand why or how specific bonds break. Dr. Winter and his students seek to understand the structure-reactivity principles for one general type of bond cleavage, specifically photochemical heterolysis of bonds between carbon and a leaving group. Heterolysis represents one of the possible ways in which a chemical bond can break, with both of the two electrons in the bond being given to one of the departing groups. Photoheterolysis reactions are important in biology, materials science and environmental chemistry. The long-term goal in this project is to create a predictive theoretical framework, which can relate chemical structure to excited state reactivity, thereby providing new guiding mechanistic principles that direct photochemical reactions. Among broader impacts activities, Professor Winter will also be involved with a Freshman Research Initiative that involves first year college students in an early multidisciplinary research experience. He will also continue to recruit undergraduates and students from underrepresented groups into his lab. To study these photoheterolysis reactions, the PI will employ a combined theoretical/experimental approach. High-level computational methods will be used to map excited state transition states and surface crossing topologies in model systems. Experimentally, spectroscopy will determine the effect of structure on the rates and mechanisms of photorelease in model systems. In particular, ultrafast femtosecond-resolved transient absorption spectroscopy will be used to determine the rates and mechanisms of photoheterolysis reactions on selected substrates, while high-level excited state calculations will be used to provide a mechanistic rationale. This research will provide a broad range of training for undergraduate and graduate students.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.