Enantioselective recognition of calix[4]arene derivatives bearing chiral bicyclic guanidinium for D/L-phenylalanine zwitterions at the air-water interface

Monolayers of the amphiphilic calixarene derivatives (BSGC, MSGC and MGC) bearing chiral bicyclic guarvidmiurn on the surface of pure water and of aqueous subphases containing L-phenylalanine or D-phenylalanine (L/D-Phe) were studied by film balance measurements. LB films deposited from the monolayers on the three kinds of subphases were investigated by circular dichroism spectra (CD). All the results indicate that BSGC, MSGC and MGC can form stable monolayers on these subphases. Moreover, BSGC (with two chiral bicyclic guanidiniurn units) can enantioselectively recognize L-aromatic amino acid and its enantioselectivity for L-Phe is better than MSGC (with one chiral bicyclic guanidinium unit) at the air-water interface, and the enantioselectivity of MGC (without hydrophobic silylether group at the arm of the chiral bicyclic guanidinium unit) for L-Phe is higher than MSGC (with hydrophobic silylether group). Therefore their enantioselectivities for L-Phe depend on the molecular structures. (C) 2004 Elsevier B.V. All rights reserved.