The comparative spreading behavior of enantiomeric and racemic tyrosine amphiphiles

Several derivatives of tyrosine or its methyl ester have been synthesized in which the para hydroxyl group on the aromatic side chain has been converted to a long chain alkyl ether or urethane. The surface behavior of these compounds is discussed. Enantiomeric discrimination, the ability of a chiral molecule to distinguish between mirror-image stereoisomers, has been investigated for the urethane derivates by comparing the surface pressure-area isotherms of the enantiomer with that of the racemic compound. Enantiomeric discrimination was demonstrated for the methyl ester analog, but was not conclusively observed for the zwitterionic compounds. Possible structural requirements for enantiomeric discrimination in a chiral molecule are discussed.