Observations and Applications of Dissociative Electron Transfer Reactions in Selected Molecular Systems

解离电子转移(DET)是化学、生物和环境系统中许多分子反应的基础。在过去的十年里，申请人(Lu)专注于各种分子系统中弱结合电子的DET反应的研究，并发现它们在各种主题中发挥着至关重要的作用，从环境重要的卤化分子的反应和电离辐射引起的DNA损伤到抗癌药物的激活。这项更新建议描述了一个连续计划，以研究在具有环境和生物意义的选定分子系统中弱结合电子的DET反应。该计划的目标是实时观察卤化分子在水溶液中在电离辐射下的DET反应，并探索其在环境和生物医学方面的应用。然而，这项提案将只关注物理科学领域的研究挑战。 对分子反应的实时观察对于了解从化学和生物到环境和医学等不同领域的许多过程和结果非常重要。在分子水平上监测反应可以识别控制反应的分子路径；一旦识别了这些路径，就可以预测、修改和控制反应。飞秒时间分辨激光光谱学(FS-TRLS)是一种非常强大的实时观察分子反应的技术。这项拟议的研究将结合FS-TRLS和DNA损伤检测来研究生物效应。具体地说，我们将演示所提出的卤化分子与电离辐射产生的弱束缚电子的DET反应是如何实时发生的，并确定它们的反应效率。 该计划建立在一项创新的研究战略和申请人在分子系统中一种新的反应机制方面的最新进展之上。它处于环境物理和化学、生物物理、生物化学、光物理、飞秒化学和飞秒生物学的前沿，并以扎实的先前研究为基础。这些结果有望深入了解卤化分子的反应机理及其对臭氧消耗和DNA损伤等重要环境和生物过程的影响。该项目还可能最终导致在环境保护和修复以及人类健康方面的重要应用。

Dissociative electron transfer (DET) underlies many molecular reactions in chemical, biological and environmental systems. Over the past decade, the applicant (Lu) has focused on research on DET reactions of weakly-bound electrons in various molecular systems, and discovered their crucial roles in a variety of topics, ranging from the reactions of environmentally important halogenated molecules and ionizing-radiation induced DNA damage to the activation of anticancer drugs. This renewal proposal describes a continuous program to study DET reactions of weakly-bound electrons in selected molecular systems of environmental and biological significance. The objectives of this program are to obtain real-time observations of the DET reactions of halogenated molecules in aqueous solutions under ionizing radiation and to explore their environmental and biomedical applications. This proposal however will only focus on research challenges in the physical sciences. Real-time observations of molecular reactions are important to understand many processes and outcomes in diverse fields from chemistry and biology, to environmental and medical sciences. The monitoring of the reactions on the molecular scale can lead to the identification of molecular pathways controlling the reactions; once the pathways are identified, the reactions can be predicted, modified and controlled. Femtosecond time-resolved laser spectroscopy (fs-TRLS) is a tremendously powerful technique for real-time observations of molecular reactions. The proposed research will combine fs-TRLS with DNA damage assays to study the biological effects. Specifically, we will demonstrate how the proposed DET reactions of halogenated molecules with weakly-bound electrons produced by ionizing radiation occur in real time, and determine their reaction efficiencies. This program is built on an innovative research strategy and the Applicant's recent advances on a novel reaction mechanism in molecular systems. It is at the cutting edge of environmental physics and chemistry, biophysics, biochemistry, photophysics, femtochemistry and femtobiology, and is grounded in solid previous studies. The results are expected to provide a deep understanding of the reaction mechanisms of halogenated molecules and their effects on important environmental and biological processes such as ozone depletion and DNA damage. This project may also ultimately lead to important applications in environmental protection and remediation, and human health.