Inclusion complex of 8-anilinonaphthalene-1-sulfonate with beta-cyclodextrin.

The interaction of 8-anilinonaphthalene-1-sulfonate with beta-cyclodextrin was investigated in 0.1 M phosphate buffer at pH 7.4 by fluorescence spectrophotometry. Utilizing the fact that the fluorescence intensity of 8-anilinonaphthalene-1-sulfonate increases in the presence of beta-cyclodextrin, the thermodynamic parameters for the inclusion complex formation were determined as follows: delta G degrees = -2.52 kcal/mol at 25 degrees C, delta H degree = -1.92 kcal/mol, and delta S degree = 2.1 eu. The driving forces for the inclusion complex formation were considered to be van der Waals-London dispersion force and hydrophobic interaction. Also, from the measurements of 1H NMR spectra and from studying the Corey-Pauling-Koltun (CPK) model, the structure of the inclusion complex was discussed.