Date of Award
Union College Only
Bachelor of Science
For over a decade, Professor Thomas C. Werner and his students have been studying the unusual florescence properties of methyl-9-anthroate. In the ground state of this ester, the carboxyl group lies perpendicular to the anthracene rings due to steric inhibition by the peri hydrogens. Werner has postulated that, upon excitation, the carboxyl group rotates to form a planar configuration with the anthracene rings, and that this rotation is the cause of the unusual spectral properties. In our work, we have attempted to prove or disprove this hypothesis. We have chosen to synthesize analogues of methyl-9-anthroate in which carboxyl group rotation is sterically hindered. Ideally, replacing one or both of the peri hydrogens by a chlorine or methyl group would hinder carboxyl group rotation most effectively. However, after a long effort, we have been unable to synthesize one of these molecules. We have, however, synthesized two esters in which the ester groups are bulky, namely, cyclohexyl-9-anthroate and t-butyl-9-anthroate. The quantum yield of these esters is solvents of various polarity has been investigated. While our results do not shed any further light on the question of carboxyl group rotation, the data do support a hypothesis set forth by Werner and Hoffman attributing the decrease in quantum yield with increasing solvent polarity to increasing internal conversion due to excited polarity to increasing internal conversion due to excited state solute solvent interactions.
Dubs, Richard Leslie, "Syntheses and fluorescence properties of sterically-hindered esters of 9-anthroic acid" (1983). Honors Theses. 1889.