Energy Partitioning Following Light Absorption by Organic Chemicals

这个更新奖，在有机动力学计划，提供了持续的支持博士彼得瓦格纳的研究能量分配在光激发有机分子。 将研究具有有限结构灵活性的光激发酮，以确定原子和轨道取向如何影响氢原子转移。 温度研究取代酮将揭示取代基是否影响氢转移速率的热力学或熵的考虑。 这些反应的应用，从邻酰基苯基醚合成苯并呋喃和其他杂环将被探索。 分子内夺氢产生中间体，其在两个碳原子中的每一个上具有一个未配对电子，导致包括环状产物在内的多种产物。 环化的几何形状以及具有相同自旋的双自由基的系统间交叉如何发生也将被追求。 其他有待研究的反应是卤代苯基酮中卤原子的光诱导裂解和烯烃与三重态苯的环加成反应。 这项研究解决了化合物的分子结构如何影响光暴露时的能量定位和所产生的激发中间体的化学反应性的基本问题。 能量在分子特定部分的定位允许合成感兴趣的选择性反应，并解决了光对生物感兴趣的系统的影响问题。

This renewal award, made in the Organic Dynamics Program, provides continued support for Dr. Peter Wagner's research on energy partitioning in photoexited organic molecules. Photoexcited ketones with limited structural flexibility will be studied to determine how atomic and orbital orientations affect hydrogen atom transfer. Temperature studies with substituted ketones will reveal whether substituents affect the rate of hydrogen transfer by enthalpic or entropic considerations. The application of these reactions to the synthesis of benzofurans and other heterocycles from o-acylphenyl ethers will be explored. Intramolecular hydrogen abstraction produces intermediates which have one unpaired electron on each of two carbon atoms, leading to a variety of products including cyclic products. The geometry of cyclization as well as how intersystem crossing of biradicals with the same spin occurs will also be pursued. Other reactions to be studied are the photoinduced cleavage of halogen atoms in halogenated phenyl ketones and the cycloaddition of alkenes to triplet benzenes. This research addresses basic questions of how molecular structure of compounds affects the localization of energy when exposed to light and the chemical reactivity of the resultant excited intermediates. The localization of energy in specific parts of molecules allows for selective reactions of synthetic interest and addresses questions of the effects of light on systems of biological interest.