Mixed supramolecular cation-carrier and anion-carrier facilitated transport for the selective alkali cations transport

In this paper, we describe the study of the membrane transport properties of mixed supramolecular macrocyclic cation-carriers [1·K]+, [2·Na]+ and phenylureidoarene anion-carriers [3–5·I]− through bulk liquid membranes. Our efforts involve the evaluation of the transport performances of these systems designed to transport ionic salts NaI and KI and strongly depending on encoded molecular features of the anion-carrier subcomponents. The differences between the transport performances can be attributed to differences between the stability of the complexes [cation-carrier][anion-carrier] in the membrane phase, inversely related to the hydrophilicity of the anion-carrier. In terms of performances, the extraction inside the membrane the transport-rate and the selectivity of K+ are higher than Na+. This indicates that the competitive extraction of [1·K]+ by anion-carriers is more effective and specific than the extraction of [2·Na+]. Despite the low rate values obtained for these transport experiments, among all phenylureidoarene anion-carriers the best selectivity is once again thermodynamically optimal for the indole-type (tryptophane-derived) phenylureidoindole compounds (image).