The Daily Bulletin Archive

Please join the Chemistry and Physics departments for the seminar "Controlling Photocycloaddition Reactions Using Host-Guest Chemistry: Development of the Cavitand-Mediation Method," presented by Mahesh Pattabiraman, associate professor of chemistry at the University of Nebraska Kearney, on Tuesday, March 28, at 12:30 p.m. in Science and Mathematics Complex 170. All students, staff and faculty are welcome. This seminar is partially funded by Faculty-Student Association.

Abstract
Photocycloaddition of alkenes is a bimolecular reaction which yields several regio- and stereoisomeric products. Selectivity in this class of reactions is predominantly influenced by the relative orientation of the reactants during the encounter between the excited state reactant and the other in ground state. The bimolecular nature necessitates proximal placement of the reactants to ensure higher quantum efficiencies as well, especially when competing unimolecular reactions are possible. A supramolecular chemistry approach to controlling selectivity and improving reaction efficiency involves using a macrocyclic host—dubbed the cavitand-mediated photocycloaddition approach. This method takes advantage of the hydrophobic spaces within macrocycles to encapsulate two photoactive compounds through hydrophobic interactions. The tight spaces within the cavitand offers both the proximity required for bimolecular reactivity and the opportunity to prealign the reactants to control regio- and/or stereoselective outcomes. Our group has been engaged in the systematic investigation of this approach to direct excited state reactivity of conjugated alkenes, which is now evolving into a reliable method for producing some dimeric adducts in a targeted manner.