Interactions and transport through liquid membranes of some dipeptide complexes with macrocyclic receptors

The study of different aspects on complexation of dipeptides (Glycyl-glycine (Gly-Gly), Glycyl-l-leucine (Gly-l-Leu), Glycyl-l-phenylalanine (Gly-l-Phe), Glycyl-l-α-alanine (Gly-l-α-Ala), and Glycyl-l-valine (Gly-l-Val)) by crown ethers and cryptand [2.2.2], their solvent extraction and their transport through liquid membrane has been investigated. Under the experimental conditions established, the dipeptides under study showed a good extractibility from aqueous phase into organic phase by crown ethers. The transport through the chloroform liquid membrane of dipeptides as ion-pairing mechanism was reported as having good yields. The relationship between stability, extractibility and the rate of the transport through liquid membrane of dipeptide complexes by macrocyclic receptors has been studied too. The thermodynamic properties of complexes (stability, enthalpy, entropy) have showed a certain influence on the extraction and the transport processes. The results have suggested the influence of ligand structure, the nature of dipeptide, the nature of solvent, the pH, and the nature of the anion upon the extraction and the transport of dipeptide complexes.