Temperature-dependent phase behavior and the crystal-forming nucleation process of ethyl 4-fluoro-2,3-dihydroxystearate monolayers.

The phase behavior of enantiomeric compounds as well as mixtures of enantiopure and racemic diastereomers of ethyl 4-fluoro-2,3-dihydroxystearates has been investigated using surface pressure-area isotherms and Brewster angle microscopy (BAM). All mixtures exhibit a small plateau region within the surface pressure-area isotherm at 20 degrees C, whereas the enantiopure compound shows an isotherm behavior similar to that of fatty acids. Corresponding to the film balance measurements, the BAM images demonstrate different shapes of the domains within the coexistence region of the liquid-condensed/liquid-expanded phase.

Organized collapse structures in mixtures of chiral ethyl 2-azido-4-fluoro-3-hydroxystearates.

Monolayers of enantiomeric compounds as well as diastereomeric mixtures and racemic/diastereomeric mixtures of ethyl 2-azido-4-fluoro-3-hydroxystearates have been investigated using surface pressure-area isotherms and Brewster angle microscopy. All monolayers collapse out of the liquid-expanded phase, forming 3D collapse structures which were visualized with scanning force microscopy. The enantiomeric compound and the diastereomeric mixtures form unique fiber-like network structures with heights between 20 and 40 nm.