Probing Highly Unstable Organic Molecules with Matrix Isolation Spectroscopy and Photochemistry

用基质隔离光谱和光化学技术探测高度不稳定的有机分子这项提议描述了一种产生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。建议的体系将主要在低温下通过基质分离方法进行研究，并结合红外光谱和UV/可见光光谱。这些结果将通过在溶液和低温固体介质中的合作激光闪光光解研究来补充，这将提供重要的反应速率数据。密度泛函理论计算将在辅助这些体系的光谱表征以及对它们的电子和结构性质的初步检验方面发挥重要作用。与合作者一起，更高水平理论的应用也将被用来更深入地探索这些物种的复杂电子结构，以及它们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、高应变的环状累积烯和相关物种，并将努力通过光谱分析和计算模拟相结合的方法来了解它们不寻常的电子结构；(2)将研究卡宾和碳正离子在极低温度下的单分子和双分子反应，并将寻找新的量子力学隧穿实例；(3)将研究极端应变的桥头烯及其形成的力学细节；(4)一个新的合作项目将尝试利用高灵敏度的激光腔衰荡光谱来探索固体介质中低温隧道反应的动力学。上述研究将围绕各种卤代化合物，特别是三氟甲基卡宾作为起点。溴化物影响这项拟议工作中将研究的新的高能有机活性中间体与星际化学、燃烧、烟尘形成、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可能性。这些研究将提供对理论构成重大挑战的分子的实验数据。长期以来，科学家们一直试图了解量子力学隧穿在从酶动力学到星际反应的各种系统中的影响；拟议的研究有望提供关于有机分子在极低温度和溶液中的隧穿反应的独特信息。与理论小组以及溶液和固体激光光谱学小组的合作，将这项工作的适用性扩大到科学的许多领域。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、精密光谱学、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.