Thermodynamics of inclusion complex formation of β-cyclodextrin with a variety of surfactants differing in the nature of headgroup

The inclusion complexation of β-cyclodextrin with various surfactants, possessing the same alkyl chain length but differing in the hydrophilic headgroup, was investigated by isothermal titration microcalorimetry. Sodium dodecyl sulfate, sodium dodecyl sulfonate, dodecyltrimethylammonium bromide and dodecyl(dimethyl)amine oxide were investigated. The major aim of this study was to elucidate the effects of temperature and the nature of the headgroup on the complex formation. Thermometric titrations were effected between the temperatures (288 and 348) K. The results provided the stoichiometry, the equilibrium constant and the reaction enthalpy of complexation. Changes in Gibbs energy, entropy and van’t Hoff enthalpy were additionally calculated.

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► Inclusion complexation of β-cyclodextrins with various surfactants.
► Thermodynamic parameters determined by titration microcalorimetry.
► Stoichiometry of complexation is 1:1.
► The binding constant decreases linearly with increasing temperature.
► Enthalpy–entropy compensation is independent of the nature of the headgroup.