Enantiomeric recognition of amino acid derivatives by chiral Schiff bases of calix[4]arene

Novel calix[4]arene Schiff bases bearing chiral substituents both on the upper and the lower rims have been developed. These chiral receptors exhibit good chiral recognition ability towards alpha-amino acid ester hydrochlorides (up to K-D/K-L = 4.36, Delta Delta G(O) = - 3.65 kJ mol(-1)) in CHCl3. The molecular recognition abilities and enantioselectivities for guests are also discussed from a thermodynamic point of view. (c) 2007 Elsevier Ltd. All rights reserved.