Diffusion Coefficients of the Ternary System α-Cyclodextrin−Sodium Benzenesulfonate−Water at 25 °C: The Effect of Chemical Equilibrium and Complex Formation on the Diffusion Coefficients of a Ternary System

Diffusion coefficients have been measured in the ternary system α-cyclodextrin−sodium benzenesulfonate−water at 25 °C. The higher mobility of the inclusion complex, compared to that of free cyclodextrin, proves that in the presence of binding complexes between solutes it is possible to measure positive cross diffusion coefficients. Previously only negative cross terms have been measured in systems containing cyclodextrin−ligand complexes. A discussion of the concentration dependence of the four diffusion coefficients and of the sign of cross terms is given.