Inclusion complexes formed by sodium dodecyl sulfate and cyclodextrin-based nanotubes

The complexation of sodium dodecyl sulfate with molecular tubes based on alpha- and beta-cyclodextrins synthesized by the suspension method was studied. The binding was studied by the isothermal titration calorimetry in aqueous solutions. For tubes based on alpha-cyclodextrins, the enthalpy of complexation, the dissociation constant of the resultant complex, and the molar fraction of binding sites in a tube were calculated. The experimental and published data on the determination of the ligand binding parameters were compared for tubes synthesized by different methods. In the case of tubes based on beta-cyclodextrins, they were shown to form associates under the conditions of experiment. As a result, the proportion of binding sites significantly decreases. The presence of associates was also confirmed by osmometric measurements. In this connection, the complexation between sodium dodecyl sulfate and beta tubes can be discussed only at the qualitative level.