Studies of Olefin Triplets and Triplet Biradicals

这项有机动力学计划的拨款支持德克萨斯大学达拉斯分校的理查德·考德威尔博士的研究。具体来说，光化学生成的反应中间体的结构、寿命和能量学将通过实验和计算方法进行探索。更好地了解瞬态反应中间体的行为和性质将为它们在光化学过程结果中的作用提供基础。烯烃三联体和三联体双自由基将被光化学生成，并通过常规的有机机理方法进行研究，以确定反应产物和推断中间体的身份；通过激光闪光光解测定瞬态寿命和系统间交叉速率；采用时间分辨光声量热法测定瞬态能量；理论上通过CAS-MCSCF计算小模型种的自旋轨道耦合。这些方法的结合将允许对系统间交叉以及这些中间体的能量面有一个基本的理解。将研究芳烯三联体、Norrish II和其他1,4-双基、三态二-甲烷双基以及由芳烯三联体产生的一些不寻常的反式环己烯和-环戊烯。

This grant in the Organic Dynamics Program supports the research of Dr. Richard Caldwell at the University of Texas at Dallas. Specifically, the structure, lifetime and energetics of photochemically-generated reaction intermediates will be explored both experimentally and by computational methods. A better understanding of the behavior and properties of transient reaction intermediates will provide a fundamental basis for their role in the outcomes of photochemical processes. Alkene triplets and triplet biradicals will be photochemically generated and studied by conventional organic mechanistic methods to determine the reaction products and infer the identity of the intermediates; by laser flash photolysis to determine transient lifetimes and intersystem crossing rates; by time-resolved photoacoustical calorimetry to determine energies of transients; and theoretically by CAS-MCSCF computations of spin-orbit coupling in small model species. The combination of these methodologies will allow a fundamental understanding of intersystem crossing as well as the energy surfaces of these intermediates. Arylalkene triplets, Norrish II and other 1,4-biradicals, triplet state di-pi-methane biradicals and some unusual trans-cyclohexenes and -cyclopentenes resulting from the alkene triplets, will be studied.