Title

Spectroscopic Determination of Binding Constants and Isomerization Behavior of Brooker’s Merocyanine Within Modified β-Cyclodextrins

Faculty Sponsor

Jennifer Holt

College

Arts and Sciences

Department/Program

Chemistry

Document Type

Poster Presentation

Symposium Date

Spring 5-2-2015

Abstract

Host-guest complexation occurs when a guest molecule is held inside a host molecule through weak intermolecular forces, without actually forming bonds. β-cyclodextrin, a host molecule, has a variety of uses and can be used in pharmaceuticals; therefore, a fundamental understanding of how intermolecular forces affect complexation is significant. Binding constants of host-guest complexes of Brooker’s merocyanine and various modified β-cyclodextrins (2-hydroxypropyl-β-cyclodextrin, sulfated β-cyclodextrin, and methyl-β-cyclodextrin) were studied using fluorescence and UV-Vis spectroscopy to determine the strength of interaction between the host molecule and the most stable form of the guest molecule. By modifying the β-cyclodextrin, the effect of ionic interaction, hydrogen bonding, and steric hindrance were compared. It was determined that β-cyclodextrin modified with sulfate groups had a much lower binding constant than the other modified β-cyclodextrins, which could be due to a combination of ionic interactions and steric hindrance. The isomerization behavior of the guest molecule within the modified β-cyclodextrins can also be affected by various forces, specifically steric hindrance and hydrogen bonding. Depending on the desired properties of the host-guest complex, a particular binding strength and isomeric form of the guest molecule may be preferred. A comparison of these results to the theoretical models will lead to verification of the effect of these forces on binding and the isomerization behavior.

Biographical Information about Author(s)

Carly Hanson is a senior chemistry major with a German minor. She began research related to host-guest complexation under the supervision of Dr. Holt in the summer of 2013. She is currently planning on attending graduate school in pursuit of her doctorate degree in chemistry. She ultimately hopes to obtain a career as a cosmetic chemist. She originally was interested in host-guest complexation due to the variety of uses of the chosen host molecule.

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