title: Supramolecular organization and heterochiral recognition in Langmuir monolayers of chiral azobenzene surfactants.
abstract: We study the self-assembly of novel azobenzene-based chiral surfactants at the air/water interface, and find that while the pure enantiomers lack the ability to organize in ordered mesophases, the racemic mixture spontaneously forms a hexatic phase at low lateral pressures, which we detect by means of Brewster angle microscopy. This work provides a unique example of heterochiral recognition in which the racemic monolayer is not only condensed with respect to the pure enantiomers, but causes an ordered mesophase to form. Although hexatic order vanishes at high surface pressures, long-range orientational order is regained for all compositions upon monolayer collapse, which proceeds through the formation of birefringent trilayers with a well-defined lateral microstructure, as revealed by atomic force microscopy.
authors.affiliation: Departament de Química Física, Institute of Nanoscience and Nanotechnology, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Pulido-Companys
authors.forename: Rosa
authors.initials: R
authors.lastname: Albalat
authors.forename: Jaume
authors.initials: J
authors.lastname: Garcia-Amorós
authors.forename: Dolores
authors.initials: D
authors.lastname: Velasco
authors.forename: Jordi
authors.initials: J
authors.lastname: Ignés-Mullol
mesh_terms: D000388:Air; D001391:Azo Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D015394:Molecular Structure; D010316:Particle Size; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D046911:Macromolecular Substances; D013501:Surface-Active Agents; D014867:Water; C009850:azobenzene