November 16, 2017
LeTourneau University, Longview, TX
Glaske O-101, 11;00 am
Merging Enamine Catalysis with Hard Metal Lewis Acid Catalysis for Asymmetric Organic Transformation
The development of new catalytic systems for new carbon-carbon and carbon-heteroatom bonding forming reactions has been a long-lasting research interest. The combination of organocatalysis with metal catalysis is an emerging field, aiming to achieve organic transformations that cannot be achieved through organocatalysis or metal catalysis alone. My research group has been engaged in developing new asymmetric reactions through combining enamine catalysis with hard metal Lewis acid catalysis. The biggest challenge in combining enamine catalysis with hard metal Lewis acid catalysis is the acid-base quenching reaction leading to catalyst inactivation. In this talk, I will present two strategies developed in our laboratory to synergistically incorporate enamine catalysis with hard metal Lewis acid catalysis. The first strategy is to use competition coordination to solve the critical acid-base quenching problem; the second strategy is to use the inversion of soft/hard approach to solve the acid-base quenching problem. Using these two strategies, we have developed a number of new asymmetric reactions including inverse-electron-demand asymmetric oxo-Diels-Alder reaction of ketones and multicomponent aza-Diels-Alder reaction of ketones.
Pi-Extended Porphyrins: Funcationalization and Applications in DSSC
Pi-extended porphyrins possess an unique set of photophysical and optoelectronic properties due to their extended pi structure. Pi-extended porphyrins promise broad application in various areas ranging from biomedicine to organic electronics due to their much broadened and red-shifted UV-Vis absorption and emision bands. In this presentation, we report methodolgy development for the synthesis and functionalization of several series of pi-extended porphyrins including push-pull dibenzoporphyrins, A2B2 push-pull tetrabenzoporphyrins, and porphyrins oligomers linked through porphyrin beta-positions. New push (electron-donating groups) and pull (electron-withdrawing) groups were introduced at the porphyrin beta-positions and push-pull effects were studied. The electronic and optical properties of these pi-extended porphyrins were measured using UV-Vis spectroscopy, steady state fluorescence spectroscopy, and cyclic voltammetry. DFT calculations were also performed for these porphyrins. The solar to electricity conversion efficiency of these porphyrins in DSSC were evaluated.
Associate Professor, Department of Chemistry
University of North Texas