Salzberg Chemistry Seminar Series

Makeda Tekle-Smith Department of Chemistry Columbia University presents "Selectivity: A Key to Synthetic Efficiency"

Abstract: Research in the Tekle-Smith group focuses on using fundamental physical organic chemistry principles to develop selective catalysts, reagents, and mechanisms involving radical intermediates. Selective chemical reactions are critical for obtaining desired materials, pharmaceuticals, and imaging agents that have the needed purity and properties to perform their planned function. The Tekle-Smith lab has leveraged non-covalent interactions to bias selectivity in photochemical reactions, where the stereochemical outcome can be predicted based on computational screening. Key to developing new approaches to overcome site- and stereo-selectivity issues is to understand the mechanistic parameters that govern reaction outcomes. Our research provides an innovative joint computational and experimental workflow to show that photochemically-mediated C–H functionalization selectivity can be tuned through rational design and therefore can lead to complimentary reaction outcomes. Specifically, we show that C–H selectivity prediction can be achieved by evaluating key substrate parameters, such as SOMO energy, electrophilicity, and steric features. We lay the experimental and computational groundwork for understanding hydrogen atom transfer selectivity in photochemical reactions by building a predictive
model based on DFT features. Additionally, the fundamental mechanistic understanding the model imparts can be applied to novel reaction discovery and optimization.

Biography: Makeda Tekle-Smith is an Assistant Professor of Chemistry at Columbia University. She obtained her B.A. in chemistry at Pomona College in 2014. She then obtained her Ph.D. with Prof. James Leighton at Columbia University in 2019. Makeda went on to conduct postdoctoral research with Prof. Abigail Doyle first at Princeton University and then at UCLA. Makeda began her independent career at Columbia University in 2022. Her research program is working to develop novel and practical strategies for controlling selectivity in radical reactions.