Fluorescence Microscopy Study of Chiral Discrimination in Langmuir Monolayers : Mixed Monolayers of N-stearoylserine Methyl ester with Achiral Additives

Langmuir monolayers of mixtures of the L and racemic forms of N -stearoylserine methyl ester (SSME) with two achiral additives, N -stearoylglycine methyl ester (SGME) and methyl stearate, were examined using fluorescence microscopy observations and surface pressure II versus area per molecule A isotherm measurements. The addition of SGME was found to promote the formation of curved condensed-phase domain structures in both racemic and enantiomeric films. The addition of methyl stearate was found to inhibit the formation of ordered dendritic or curved structures overall. SGME appears to be miscible with SSME in mixed monolayers, while methyl stearate is partially miscible. II-A isotherms for the mixtures of L-SSME with methyl stearate show evidence for partial miscibility and positive deviations from ideality while those for mixed films of L-SSME and SGME show evidence for positive deviations from ideality. Isotherms for mixed films of racemic SSME and methyl stearate show evidence for partial miscibility, while those for racemic SSME with SGME indicate nonideal behavior.