Exploring and Understanding the Effect of Cation-Pi Interactions in Asymmetric Catalysis

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In this project, funded by the Chemical Structure, Dynamics and Mechanisms-B Program of the Chemistry Division, Professor Sheryl Wiskur of the Department of Chemistry and Biochemistry at the University of South Carolina is attempting to understand how intermolecular interactions control chemical reactions in order to rationally design catalysts. Optically active intermediates are of increasing in importance in the pharmaceutical and agrochemical industries. New approaches to obtaining these commercially important compounds are constantly being developed. It is important to understand the interactions that aid in achieving selective product formation in order to rationally design catalysts. This research investigates how the intermolecular interactions, termed a cation-pi interactions, are involved in controlling selectivity. The research could aid the development of more efficient asymmetric catalysts, which are needed in drug development and the manufacture of many other chemicals. The project also takes into account the valuable training graduate students receive while carrying out the experiments to understand this supramolecular interaction. Broader impacts include the mentoring of women scientists to aid in retaining women in science.Delocalized cations are often proposed to aid in controlling asymmetric reactions through cation-pi interactions between the substrate and catalyst, yet delocalized cations have not been as widely studied. This project explores this supramolecular interaction in two ways. The thermodynamics of binding of four common organocatalyst core structures will be studied. The team will also investigate how the binding trends relate to the rate and selectivity of a model reaction as electronics on the pi system are altered. The electrostatics of binding are explored computationally to understand binding orientations and localization of charge. The electronic changes in the cation (i.e., substituted catalysts) are examined to understand how those changes affect the same model reaction in terms of thermodynamics, kinetics, and selectivity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.