Complexation thermodynamics of α-cyclodextrin with ionic surfactants in water.

The interaction of α-cyclodextrin (α-CD) with ten ionic surfactants (S) in water was systematically examined using isothermal titration calorimetry. The S comprised cationic and anionic head groups while the hydrocarbon alkyl chain length varied from eight to fourteen carbon atoms. The heat data were measured at five temperatures ranging from 283.15K to 318.15K and were treated simultaneously allowing the estimation of a thermodynamically consistent temperature dependence of the equilibrium constant, as well as the enthalpy and heat capacity for the sequential formation of the [α-CD·S] and the [α-CD