Spring Chem501 Seminar
UT Host: Dr. John Brantley
Speaker: Dr. William Dichtel
Robert L Letsinger Professor of Chemistry
Title: “Dynamic Imine Bonds in Covalent Organic Frameworks and Related Assemblies”
Abstract: Covalent organic frameworks (COFs) are highly modular, porous, crystalline polymers of interest for charge storage devices, nanofiltration membranes, optoelectronic devices, and other applications for which the precise assembly of monomers is desired. COFs are typically synthesized as microcrystalline powders, a morphology that limits their performance in these applications, and their limited solubility precludes large-scale processing into more useful morphologies and devices. A general, scalable method to exfoliate two-dimensional imine-linked COF powders by temporarily protonating their linkages will be presented. The resulting suspensions were cast into continuous, crystalline COF films up to 10 cm in diameter. This strategy was successfully applied to three different COF structures, and excellent film thickness control (50 nm to 20 µm) was achieved by modifying the suspension composition, concentration, and casting protocol. Acid-mediated exfoliation is a promising strategy for solution processing readily accessible imine-linked COF powders into functional devices. Perhaps surprisingly, this response to acid is quite different in molecular analogues of the COF structure, and the introduction of acid induces strong non-covalent interactions and supramolecular polymerization rather than exfoliation. Examples of this phenomenon will be presented as a modular route to synthetic nanotubes with strong cohesive interactions.
Bio: Will Dichtel was born in Houston, Texas and was raised in Roanoke, Virginia. He was an undergraduate student at MIT, where he majored in chemistry and was fortunate to gain his first research experience working in the laboratory of Prof. Tim Swager. He then moved to UC-Berkeley for graduate school, where he earned his Ph.D. for investigating light harvesting macromolecules under the supervision of Prof. Jean M. J. Fréchet. He next moved to Los Angeles for a joint postdoctoral appointment with Prof. Fraser Stoddart, then at UCLA, and Prof. Jim Heath, then at Caltech. There his research focused on developing efficient strategies for the synthesis of mechanically interlocked compounds and incorporating these molecules onto surfaces and into solid-state devices. Prof. Dichtel began his independent career in the Department of Chemistry and Chemical Biology at Cornell University in 2008 and was promoted to the rank of Associate Professor in 2014. He moved to Northwestern University in the summer of 2016 as the Robert L. Letsinger Professor of Chemistry. In 2016, he co-founded the startup company, CycloPure, to commercialize his group’s discovery of porous cyclodextrin-containing compounds for removing trace organic contaminants from water.
Dichtel’s research has been recognized with a number of national awards, including Guggenheim and MacArthur Fellowships, the Leo Hendrik Baekeland Award from the North Jersey Section of the ACS, the National Fresenius Award from the Phi Lambda Upsilon National Chemistry Honor Society, the Polymer International – IUPAC Award for for Creativity in Applied Polymer Science, the Camille Dreyfus Teacher-Scholar Award, an Arthur C. Cope Scholar Award from the American Chemical Society, a Cottrell Scholar Award from the Research Corporation for Science Advancement, the Sloan Research Fellowship, and a Beckman Young Investigator Award from the Arnold and Mabel Beckman Foundation. Will is an avid open-water swimmer and enjoys travel and the outdoors.
Thursday, January 23 at 3:45pm to 5:00pm
Buehler Hall, 555
1420 Circle Drive, Knoxville, TN 37996