A Preliminary Investigation of the Complexation of Dopamine by p‐Sulfonated Calix[4, 6] Arene and β‐Cyclodextrin Using Fluorescence Spectrometry

Abstract

The inclusion complexes of p‐sulfonated calix[4, 6] arene and β‐cyclodextrin with dopamine were studied by fluorescence spectrometry in aqueous media. It was found that the fluorescence intensity of dopamine regularly decreased upon the addition of p‐sulfonated calix[4, 6] arene, on the contrary, it increased upon the addition of β‐cyclodextrin. ¹H NMR spectra were applied to verify the formation of the complexes. According to the experimental results, 1:1 stoichiometry for the complexes was established and their association constants at 25°C were calculated by applying a deduced equation. Judging from the magnitude of their inclusion constants, the p‐sulfonated calix[4, 6] arene showed better inclusion capability than β‐cyclodextrin. The probable interaction mechanisms are proposed.

Keywords:

• β‐Cyclodextrin
• dopamine
• fluorescence spectrometry
• inclusion interaction
• p‐sulfonated calix[4, 6] arene

Acknowledgments

The authors gratefully acknowledge the financial support of the National Natural Science Foundation of the People's Republic of China (20375001, 20575001) and the Education Commission Natural Science Foundation of Anhui Province (2005KJ017ZD).