The Role of Non-covalent Interactions in the Excited State Dynamics of Heterocyclic Compounds.

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In this project, funded by the Chemical Structure Dynamics and Mechanisms A (CSDM-A) program of the Chemistry Division, Professor de Vries at the University of California Santa Barbara will study how heterocyclic compounds respond to exposure to ultraviolet (UV) radiation. Such compounds form the basic structure of DNA bases as well as many other important molecules and their response to light plays a role in many practical processes. For example, the photochemistry following UV absorption constitutes a fundamental step in radiation-induced DNA damage. UV photo-selection may have played a key role in prebiotic chemistry on an early earth. These same processes also find applications in a variety of modern materials. These topics, in combination with cutting-edge laser and computational techniques, lend themselves to outreach activities that will be based on this work. Both undergraduate and graduate students will receive training in the design and construction of advanced experimental instrumentation, complex computer simulation, and conducting fundamental research. This work will be carried out in collaboration with scientists at Jackson State University, an HBCU. Professor De Vries and members of his group will serve as mentors in various programs aimed at broadening participation of members of underrepresented groups in STEM. The precise effects of UV radiation depend critically on molecular structure and the fundamental photochemistry is affected by interactions with other molecules. The laboratory of Professor de Vries at UCSB will study fundamental photoproperties of heterocyclic compounds and clusters containing them experimentally by gas phase spectroscopy and collaborate with computational chemists to compare the results with quantum chemical modeling. The experiments will investigate how pi-stacking and hydrogen bonding affect the excited state potential energy landscape of heterocyclic compounds and how that changes the photochemical outcomes. The project will study these molecular systems in the picosecond and nanosecond time domains and model the results with high level quantum computations.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.