Andrew L. Sargent
Professor, Inorganic and Theoretical Chemistry
Army High Performance Computing Research Center (1992-1994)
Postdoctoral Fellow, Minnesota Supercomputer Institute (1991-1992)
Ph.D., Texas A&M University (1991)
B.A., The Colorado College (1985)
Much of the emphasis in our research group involves the application of accurate quantum chemical methods to the analysis of molecular systems. Two systems are currently garnering the bulk of our attention, and they are briefly described below.
Crown ether compounds are well known for their ability to selectively bind metal ions in the electron-rich pocket of the macrocycle. Interest in these systems stems, in part, from their enzyme-like specificity and their potential application as ion transport and sequestering agents of radionuclides in the treatment of streams contaminated by nuclear waste or heavy metal ions. Collaborators in the research group of Dr. John Sibert at the University of Texas at Dallas have recently derivatized the standard crown ether moiety with a redox-active substituent that is positioned to directly participate in host-guest interactions. These new molecules, dubbed Wurster’s crowns for their structural relationship to the well-known Wurster’s reagent (N,N,N’,N’-tetramethyl-p-phenylenediamine), have demonstrated numerous interesting properties, and our group is applying accurate computational methods to investigate the role of the redox-active moiety in metal-ion binding for both the neutral and oxidized species. Future work will involve the analysis of macrocycles with multiple redox centers and/or nitrogen and sulfur donor atoms, and will probe their application in chemical sensing, heavy-metal ion transport and redox-switchable catalysis.
Rhodium catalyzed hydroacylation:
Rhodium catalyzed hydroacylation effects the rapid synthesis of cyclopentanones, which are important intermediates in a variety of pharmaceuticals. A simple catalytic cycle of the process is shown in the accompanying schematic. Bosnich (Fairlie, D.P.; Bosnich, B. Organometallics 1988, 7, 946-954) attempted a detailed examination of the reaction mechanism using deuterium-labeling studies, but was thwarted by the overall complexity of the reaction and a lack of isolable intermediates. In this context, we are applying accurate computational methods to the analysis of the catalytic mechanism.