Ultrafast Dynamics of Bimolecular Reactions in Solution

对溶液中双分子反应动力学的研究提供了一种理解许多化学反应的基本方面和基本步骤的方法，这些反应是重要的，其中包括亲核取代、消除和加成反应以及许多催化反应。在这个项目中，氢键和络合对液相中双分子反应势能景观的影响将被研究。氢键在酶催化反应中尤为重要，在酶催化反应中，过渡态以大量氢键和h转移反应为特征。然而，对它们的作用的详细了解仍然缺失。因此，本项目将研究那些复杂性较低的反应，这些反应有望揭示这些反应的基本步骤。第一部分介绍了CN自由基与小反应伙伴的反应。使用具有不同氢键性质的共反应物和溶剂有望阐明周围溶剂分子通过络合和/或质子转移反应对势能景观的作用。本项目第二部分将研究CN和OH自由基在水中和与水的反应性。这些反应将直接揭示无处不在的氢键的作用。飞秒时间分辨瞬态红外光谱和紫外/可见光谱的结合将用于实时研究所涉及的配合物的形成，氢键的形成和断裂，产物形成的速率和振动弛豫机制。

The investigation of bimolecular reaction dynamics in solution provides a means of understanding the fundamental aspects and elementary steps that are important in numerous chemical reactions, among them nucleophilic substitution, elimination and addition reactions, and many catalysed reactions. In this project, the influence of hydrogen bonding and complexation on the potential energy landscape of bimolecular reactions in the liquid phase will be investigated. Hydrogen bonds are particularly important in, e.g., enzyme catalysed reactions, where the transition state is characterized by a large number of hydrogen bonds and H-transfer reactions. A detailed understanding of their role is, however, still missing. For this reason, reactions with less complexity, which are expected to shed light on the very basic steps of these reactions, will be investigated in this project. The first part covers the reactions of CN radicals with small reaction partners. The use of co-reactants and solvents with different H-bonding properties is expected to elucidate the role of surrounding solvent molecules on the potential energy landscape by complexation and/or proton transfer reactions. The reactivity of CN and OH radicals in and with water will be investigated in the second part of this project. These reactions will provide direct insight into the role of ubiquitous hydrogen bonds. A combination of femtosecond time-resolved transient IR and UV/vis spectroscopy will be used to look into the formation of the involved complexes, the making and breaking of H-bonds, the rates of product formation and vibrational relaxation mechanisms in real time.