Ultrafast Dynamics of Bimolecular Reactions in Solution

溶液中双分子反应动力学的研究为理解许多化学反应中重要的基本方面和基本步骤提供了一种手段，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，将研究氢键和络合对双分子反应在液体中的势能分布的影响。氢键在例如酶催化的反应中特别重要，其中过渡态的特征是大量的氢键和H转移反应。然而，对它们的作用仍缺乏详细的了解。出于这个原因，这个项目将研究复杂性较低的反应，这些反应有望揭示这些反应的非常基本的步骤。第一部分介绍了CN自由基与小分子反应伙伴的反应。具有不同氢键性质的共反应物和溶剂的使用有望通过络合和/或质子转移反应来阐明周围溶剂分子对势能格局的作用。本项目的第二部分将研究CN和OH自由基在水中和与水的反应活性。这些反应将提供对无处不在的氢键作用的直接洞察。飞秒时间分辨的瞬时红外光谱和UV/Vis光谱将被用来实时研究所涉及的络合物的形成、氢键的形成和断裂、产物的形成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.