title: Chiral symmetry breaking by spatial confinement in tactoidal droplets of lyotropic chromonic liquid crystals.
abstract: In many colloidal systems, an orientationally ordered nematic (N) phase emerges from the isotropic (I) melt in the form of spindle-like birefringent tactoids. In cases studied so far, the tactoids always reveal a mirror-symmetric nonchiral structure, sometimes even when the building units are chiral. We report on chiral symmetry breaking in the nematic tactoids formed in molecularly nonchiral polymer-crowded aqueous solutions of low-molecular weight disodium cromoglycate. The parity is broken by twisted packing of self-assembled molecular aggregates within the tactoids as manifested by the observed optical activity. Fluorescent confocal microscopy reveals that the chiral N tactoids are located at the boundaries of cells. We explain the chirality induction as a replacement of energetically costly splay packing of the aggregates within the curved bipolar tactoidal shape with twisted packing. The effect represents a simple pathway of macroscopic chirality induction in an organic system with no molecular chirality, as the only requirements are orientational order and curved shape of confinement.
authors.affiliation: Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
authors.forename: Luana
authors.initials: L
authors.lastname: Tortora
authors.forename: Oleg D
authors.initials: OD
authors.lastname: Lavrentovich
mesh_terms: D050866:Liquid Crystals / Q000737:chemistry*; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D011108:Polymers; D012996:Solutions