Conference Papers

Calixarenes have attracted considerable interest in the growing field of supramolecular chemistry. By their availability and easily functionalization at either the upper or lower rim of the molecular skeleton among potential building blocks, calixarenes have become attractive receptors, versatile molecular scaffolds for self-assembling system such as molecular capsule and well-defined functional nanostructures. Their ability to encapsulate the biological compounds such as amines, amino acids or peptides recommends them as biomimetic receptors for separation processes. In the present contribution, we have reported aspects of complex formation, solvent extraction, and transport through liquid membrane of amino acids by calix[n]arene derivatives. The complexation properties of calix[n]arenes towards amino acids have been evaluated by calorimetric titration and UV Vis spectrometry. The effects of physicochemical parameters that may influence the separation of amino acids by extraction process, and the transport through liquid membrane using calix[n]arenes as carriers have been investigated.

There are studies dedicated to the molecular inclusion of biological substrates, like biogenic amines, amino acids, and peptides by cyclodextrins [1-3]. The interactions involved in cyclodextrin complexes (hydrogen bonding, van der Waals forces, release of conformational strain, change–transfer, electrostatic and hydrophobic interactions) are known to play an important role in pharmaceutical science, biochemistry, immunochemistry and also in analytical chemistry. Thus, cyclodextrins and their derivatives form inclusion complexes with aromatic amino acids or their oligopeptides, being well known that the aromatic amino acid residues are responsible for interaction of proteins/peptides. The analytical applications in extraction and transport processes of biological compounds such as amino acids by using modified cyclodextrins are presented. In order to outline the possibility of modified cyclodextrins acting as carriers through membrane, we have investigated some aspects of the solvent extraction and the transport through chloroform liquid membrane of some amino acid methylesters in the presence of picric acid or tropaeolin 00. The effects of physicochemical parameters involved in extraction and transport processes such as the structure of cyclodextrin, the nature of the anion used as counterion, and the structure of amino acid have been studied. Moreover the influence of the composition and the structure of the compounds under study upon the partition processes occurring in triphasic systems have been reported.