Semibullvalenes as Transition State Probes: Homoaromaticity and Matrix Effects

该奖项支持爱达荷州大学的理查德·V·威廉姆斯教授的工作。这项研究将涉及通过理论计算预测的分子的研究，这些分子表现出难以捉摸的同芳性。以前制备的几个分子在溶液(凝聚相)中没有表现出这种性质，但现在已经表明，在选定的体系(半牛角戊烯和巴巴拉烷)中，溶剂的极性对Cope重排的障碍(决定同芳性至关重要)有深远的影响。在此基础上，我们将考察基质效应对双烯类半牛角戊烯基态结构的影响，阐明基质效应的机理，并在此基础上制备最佳体系。如果成功，这些环化的半牛角烯将允许对周环化学反应的过渡态进行(有效的)直接光谱观察。这项研究的更广泛影响包括培训年轻科学家，他们不仅在合成敏感分子方面获得广泛的经验，而且还将接触到广泛的最先进技术以及实验和理论之间的协同作用。这项研究的一个特点是与世界各地的团体合作，这将使学生接触到跨学科和协作研究。此外，对这些分子的研究将极大地促进对复杂电子相互作用的理解，并将对这些反应的性质和基质效应提供相当大的洞察力。控制分子内的电子相互作用，特别是通过基质效应，具有重要的基础意义和重要意义，在催化、传感和材料性质(例如，非线性光学效应)方面具有潜在的应用前景。

With this award, the Organic and Macromolecular Chemistry Program supports the work of Professor Richard V. Williams of the University of Idaho. This research will involve the study of molecules predicted by theoretical calculations to exhibit the elusive property of homoaromaticity. Several previously prepared molecules were shown not to exhibit this property in solution (condensed phases) but it has now been shown that solvent polarity has a profound influence on the barrier to the Cope rearrangement (crucial in determining homoaromaticity) in selected systems (semibullvalenes and barbaralanes). Matrix effects on the structure of the ground states of bisannelated semibullvalenes will be examined, the mechanism of the matrix effects will be elucidated and optimum systems will be prepared based on these studies. If successful, these annelated semibullvalenes will allow the direct spectroscopic observation of (what is effectively) the transition state for a pericyclic chemical reaction. The broader impacts of this research include the training of young scientists who will not only gain broad experience in the synthesis of sensitive molecules, but will also be exposed to a wide range of state-of-the-art techniques and to the synergy between experiment and theory. A feature of this research is collaborations with groups around the world which will expose the students to interdisciplinary and collaborative research. In addition, study of these molecules will greatly advance the understanding of the complex electronic interactions and will provide considerable insight into the nature of these reactions and into matrix effects. Controlling the electronic interactions within a molecule, particularly through matrix effects, is of significant fundamental interest and importance and has the potential for applications in catalysis, sensing and materials properties (e.g., non-linear optical effects).