Influence of the Structure of Nonionic Surfactants and the Length of Alkyl Substituents of Calix[4]resorcinarenes on Their Solubility, Acid–Base, and Complexation Properties

Abstract

Regularities of solubilization of calix[4]resorcinarenes (H8L) with the variable length of hydrophobic radicals (R = CH3, C3H7, C5H11, C7H15, C8H17, C9H19, C11H23) by the micelles of nonionic surfactants Triton X-100 and Triton X-405 in aqueous solutions were studied using solubility measurements. It was found that the solubilization capacity of surfactant micelles with respect to H8L and [H4L]4– depends on the extension (thickness) of their polar layers. It was shown by means of potentiometric titration that, in solutions of nonionic surfactants, the constants of the interaction between tetraanions [H4L]4– and tetrametylammonium ions depend on the structure and concentration of nonionic surfactants and the hydrophobicity of H8L molecules. A change in the affinity of the [H4L]4– anions for protons and tetramethylammonium cations in nonionic surfactant solutions was revealed in relation to the length of substituents R and reagent concentrations.