Arts and Sciences
The binding of a guest molecule to a host system occurs through weak molecular interactions instead of through the formation of chemical bonds. The relative strength of these interactions can be understood by comparing the binding constant in related host-guest systems. Β-cyclodextrin (β-CD) is a seven-membered ring of glucose units which was used as the host molecule due to its basket-like shape. This shape allows Brooker’s merocyanine (BM), a highly conjugated guest molecule that is sensitive to its environment, to enter the cavity and interact with substituents located along the primary and secondary rims of the CD. This project measured the changes in the equilibrium binding constant due to different modifications to the CD, as well as the isomerization of BM within the cavity using UV-Vis and fluorescence spectroscopy. Binding constants were determined for different CD modifications, including β-CD, hydroxypropyl-β-CD, hydroxyethyl-β-CD, and sulfated β-CD (sodium salt). The largest effect of these substituents was the hindrance of the binding by the sulfate groups due to either steric effects or ionic interactions. A better understanding of these factors that affect binding and how molecules behave within the cavity will allow for more accurate predictions of their behavior under different conditions.
Averill, Benjamin and Larson, Kelsey, "Molecular Hospitality: The Interactions of Brooker’s Merocyanine with Modified Cyclodextrins" (2014). Symposium on Undergraduate Research and Creative Expression (SOURCE). 310.