Probing Highly Unstable Organic Molecules with Matrix Isolation Spectroscopy and Photochemistry

用基质隔离光谱和光化学方法探测高度不稳定的有机分子本提案描述了一个生成和研究其性质处于稳定性和反应性极限的有机分子的计划。所提出的系统将主要在低温下通过基质分离方法，用红外和紫外/可见光谱进行研究。这些结果将通过在溶液和低温固体介质中的协同激光闪光光解研究得到补充，这将提供重要的反应速率数据。密度泛函理论计算将在帮助这些系统的光谱表征和它们的电子和结构性质的初步检查中发挥重要作用。与合作者一起，更高层次理论的应用也将用于更深入地探索这些物种的复杂电子结构，以及它们的反应中的量子力学隧道效应。该项目的主要目标包括：(1)寻找新的高应变环积云及其相关物种，并通过光谱学和计算建模相结合的方法了解其不同寻常的电子结构；(2)研究极低温下碳正离子和碳正离子的单分子和双分子反应，寻找量子力学隧穿的新实例；(3)将研究极度紧张的桥头堡烯烃及其形成的机械细节；(4)一个新的合作项目将尝试利用高灵敏度激光腔衰荡光谱来探索固体介质中低温隧穿反应的动力学。上述研究将围绕各种光环，特别是以三氟甲基羰基为出发点。这项工作将研究的新型高能有机反应中间体与星际化学、燃烧、烟灰形成、富勒烯生产、磁性材料、酶转化和有机合成等广泛领域相关。此外，这些研究将为广泛用于光亲和标记的系统提供新的信息，并为发现新的标记剂提供潜力。这些研究将提供分子的实验数据，对理论提出重大挑战。长期以来，科学家们一直试图了解量子力学隧道效应在各种各样的系统中的影响，从酶动力学到星际反应；拟议的研究有望提供有机分子在极低温和溶液中隧穿反应的独特信息。与理论小组、溶液和固态激光光谱学小组的合作，扩大了这项工作在许多科学领域的适用性。这些研究将为学生和同事提供特别广泛的培训，包括有机合成、复杂光谱学、光化学、物理有机技术和现代理论方法论。

Probing Highly Unstable Organic Molecules with Matrix IsolationSpectroscopy and PhotochemistryIntellectual Merit This proposal describes a plan for the generation and investigation of organic molecules whose properties are at the limits of stability and reactivity. The proposed systems will be investigated primarily at cryogenic temperatures by matrix isolation methods, with IR and UV/visible spectroscopy. These results will be complemented by collaborative laser flash photolysis studies both in solution and in low temperature solid media, which will provide important reaction rate data. Density Functional Theoretical calculations will play a significant role in aiding the spectroscopic characterization of these systems and in initial examinations of their electronic and structural properties. With collaborators, applications of higher level theory will also be used to explore the complex electronic structures of these species in greater depth, as well as quantum mechanical tunneling in their reactions. Primary objectives of the project include the following: (1) New, highly strained cyclic cumulenes and related species will be sought, and efforts will be made to understand their unusual electronic structures through a combination of spectroscopy and calculational modeling; (2) Unimolecular and bimolecular reactions of carbenes and carbocations at very low temperatures will be investigated, and new instances of quantum mechanical tunneling will be sought; (3) Extremely strained bridgehead alkenes, as well as mechanistic details of their formation, will be investigated; (4) A new collaborative project will attempt to utilize highly-sensitive laser cavity ring-down spectroscopy to explore the kinetics of low-temperature tunneling reactions in solid media. The above studies will revolve around a variety of halo- and, in particular, trifluoromethylcarbenes as starting points.Broader Impact The new high-energy organic reactive intermediates that will be investigated in this proposed work have relevance to such broad areas as interstellar chemistry, combustion, soot formation, fullerene production, magnetic materials, enzymatic transformations and organic synthesis. Moreover, these investigations will provide new information on systems which are widely utilized for photoaffinity labeling and offer the potential for discovery of new labeling agents. These studies will provide experimental data on molecules which pose significant challenges for theory. Scientists have long sought to understand the effects of quantum mechanical tunneling in a very wide variety of systems, ranging from enzyme kinetics to interstellar reactions; the proposed studies promise to provide unique information on the tunneling reactions of organic molecules, both at very low temperatures and in solution. Collaborations with a theoretical group, and with solution and solid state laser spectroscopy groups, broaden the applicability of this work to many areas in science. The investigations will offer especially broad training for students and co-workers, including organic synthesis, sophisticated spectroscopy, photochemistry, physical organic techniques, and modern theoretical methodology.