Calixarene derivatives as carriers in liquid membrane transport

The liquid membrane transport of some biogenic amines (n-buthylamine, hexylamine) and aromatic amino acids methylesters by p-tert-butylcalix[n]arenes (n = 6.8) were investigated. The transport driving force was the pH gradient between the source and the receiving phases. The complexation properties of the calixarenes under study towards amines and amino acids were evaluated. Several factors influencing the transport through liquid membrane were considered aiming to develop a mechanism model. The effect of the type of p-tert-butylcalixarene on the transport was also investigated. The results showed that the inclusion abilities of the investigated hosts were correlated with their conformational properties.

The transport, assisted by pH gradient, of some amines and aromatic amino acids in protonated form as ion pairs in the presence of picrate was performed. The influence of the composition and structure of the above compounds upon the partition processes occurring in triphasic systems was also studied. The main target of our experiments was to completely elucidate the transport mechanisms of these complexes through liquid membranes in order to perform selective separation of amine compounds from mixtures.