INTERACTION OF 8-ANILINO-1-NAPHTHALENESULFONATE WITH 2,6-DI-O-METHYLCYCLOMALTOHEPTAOSE

The interaction of 8-anilino-1-naphthalenesulfonate (ANS) with 2,6-di-0-methyl-cyclomaltoheptaose (2,6-DM-betaCD) was investigated in a 0.1 M phosphate buffer at pH 7.4 by fluorescence spectrophotometry. Utilizing the fact that the fluorescence intensity of ANS increases in the presence of 2,6-DM-betaCD, the thermodynamic parameters for inclusion complex formation were determined as follows: DELTAG-degrees = -10.3 kJ.mol-1 at 25-degrees-C, DELTAH-degrees = -13.4 kJ.mol-1, DELTAS-degrees = -10.9 J.deg-1.mol-1. The main driving force for the inclusion complex formation was considered to be the Van der Waals-London dispersion forces, while the contribution of the hydrophobic interaction was small. Also, from the measurements of proton nuclear magnetic resonance spectra and studies with Corey-Pauling-Koltun models, the probable structure was determined.