Mechanisms of ground and excited state organic reactions

有机化学是研究含碳化合物的性质和反应的学科。 当这些化合物发生反应时，原子之间的键在反应物转化为产物时形成和断裂。 术语“机制”用于描述这些键变化的细节：哪个键首先形成或断裂，以及在途径上是否存在反应性的、不可分离的中间体。 反应机制的实验证据和从实验数据中制定这些机制的逻辑方法是我研究的主题。 对反应机理的理解是基础研究，并导致新反应的预测和发展。我们研究的有机反应有两种不同的类型：基态和激发态。 在基态反应中，用来破坏化学键的唯一能量来源是热。 在某些情况下，即使在室温下可用的热量也足以使反应迅速进行;在其他情况下，必须通过外部加热来提高温度。 在激发态反应中，反应物可用的额外能量由可见光或紫外光范围内的光（光子）提供。 由于光子提供的能量足以打破化学键，激发态的反应性通常比基态高数百万倍，而且通常通过完全不同的途径反应，产生不同的产物。 有机光化学反应的研究远不如基态反应的研究先进。 因此，仍然不可能可靠地预测从新反应物获得的产物的结构和产率。 我们的总体目标是提高对基态和激发态反应性的基本理解。

Organic chemistry is the study of the properties and reactions of carbon containing compounds.  When reactions of these compounds occur, bonds between atoms are made and broken as the reactant is converted to the product.  The term "mechanism" is used to describe the details of these bond changes: which bond is made or broken first and are there reactive, non-isolable intermediates on the pathway.  The experimental evidence for reaction mechanisms and the logical methods by which these mechanisms are formulated from experimental data is the subject of my research.  The understanding of reaction mechanisms is fundamental research and leads to the prediction and development of new reactions. The organic reactions we study are of two different types; ground state and excited state.  In a ground state reaction the only source of energy provided to break chemical bonds is heat.  In some cases, even the heat available at room temperature is enough to make the reactions proceed rapidly; in other cases, the temperature must be raised by external heating.  In excited state reactions, the extra energy available to the reactant is provided by light (photons) in the visible or ultraviolet range.  Since the energy provided by a photon is sufficient to break chemical bonds, excited states are normally millions of times more reactive than ground states and moreover, often react by completely different pathways to give different products.  The study of organic photochemical reactions is much less advanced than the study of ground state reactions.  Consequently, reliable predictions about the structure and yield of the products to be obtained from a new reactant are still not possible.  Our overall goal is to improve the fundamental understanding of both ground and excited state reactivity.