Semibullvalenes as Transition State Probes: Homoaromaticity and Matrix Effects

Regents Of The University Of Idaho, Moscow ID

Investigators

Abstract

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).