Spectroscopic Study of Dye Isomerization in a Host-Guest Complex
Arts and Sciences
Host-guest complexes are systems in which a guest molecule binds to a host molecule through weak intermolecular interactions, such as van der Waals interactions or hydrogen bonding. β-cyclodextrin, the host molecule, is a seven-membered ring with a hydrophobic inner cavity and a hydrophilic outer surface. Brooker’s merocyanine, the guest, is a dye molecule with a photo-induced isomerization cycle. The isomerization of Brooker’s merocyanine was analyzed using UV-Vis spectroscopy to understand differences in the behavior of the dye in the solution and in modified cyclodextrin cavities. The molecule in solution cannot be isomerized directly from the trans to cis configuration unless energy in the form of UV light is added. However, when the dye is complexed with β-CD, it undergoes isomerization without UV light exposure. It appears the dye molecule changes conformation within the cyclodextrin to relieve the strain inflicted by the cavity. Different modifications to the outer surface of the cyclodextrin have been studied to see how these modifications might affect this unique isomerization behavior. By understanding guest behavior in the cavity, a molecular level understanding of host-guest chemistry will help to improve practical applications of materials.
Repak, Miroslava, "Spectroscopic Study of Dye Isomerization in a Host-Guest Complex" (2014). Symposium on Undergraduate Research and Creative Expression (SOURCE). 387.