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. Utiliz ing the fact that the fluorescence intensity of ANS increases in the p resence of 2,6-DM-betaCD, the thermodynamic parameters for inclusion c omplex formation were determined as follows: DELTAG-degrees = -10.3 kJ .mol-1 at 25-degrees-C, DELTAH-degrees = -13.4 kJ.mol-1, DELTAS-degree s = -10.9 J.deg-1.mol-1. The main driving force for the inclusion comp lex formation was considered to be the Van der Waals-London dispersion forces, while the contribution of the hydrophobic interaction was sma ll. Also, from the measurements of proton nuclear magnetic resonance s pectra and studies with Corey-Pauling-Koltun models, the probable stru cture was determined.