J. Nishijo et al., INTERACTION OF 8-ANILINO-1-NAPHTHALENESULFONATE WITH HEPTAKIS(2,3,6-TRI-O-METHYL)-BETA-CYCLODEXTRIN, Chemical and Pharmaceutical Bulletin, 42(4), 1994, pp. 761-767
The interaction of 8-anilino-1-naphthalenesulfonate (ANS) with heptaki
s(2,3,6-tri-O-methy)-beta-cyclodextrin (TOM-beta-CD) was investigated
in a 0.1M phosphate buffer at pH 7.4 by fluorescence spectrophotometry
. Utilizing the fact that the fluorescence intensity of ANS increases
in the presence of TOM-beta-CD, the thermodynamic parameters for inclu
sion complex formation were determined as follows: Delta G degrees=-8.
95kJ.mol(-1) at 25 degrees C, Delta H degrees=-10.9kJ.mol(-1), Delta S
degrees=- 6.3J.mol(-1).K-1. The main driving force for the inclusion
complex was considered to be the van der Waals-London dispersion force
s, while the contribution of the hydrophobic interaction was small. Al
so, from the measurements of proton nuclear magnetic resonance spectra
and studies with Corey Pauling Koltun models, the probable structure
of the complex was determined. Further, the effects of permethylation
on inclusion complex formation were discussed.