Chiral calix[4]arenes bearing aminonaphthol moieties as membrane carriers for amino acid methyl esters and mandelic acid

Chiral calix[4]arene derivatives functionalized at the lower rim with chiral aminonaphthol units have been prepared. The structures of these receptors were characterized by a combination of (1)H NMR, (13)C NMR, FTIR and elemental analysis. The transport of amino acid derivatives (phenylglycine, phenylalanine and tryptophan methyl ester hydrochlorides) and mandelic acid were studied through a bulk liquid membrane in the presence of chiral calix[4]arene derivatives. The transport rate and enantioselectivity of the amino acid esters studied depended mainly upon the structure of the chiral receptors. The influence of calixarene and amino acid ester structures upon transport through a liquid membrane is discussed. The receptors with hydrogen bonding sites and aromatic groups showed considerable higher transport rates and stereoselectivities. (C) 2011 Elsevier Ltd. All rights reserved.