Chiral symmetry breaking by spatial confinement in tactoidal droplets of lyotropic chromonic liquid crystals

Proc Natl Acad Sci U S A. 2011 Mar 29;108(13):5163-8. doi: 10.1073/pnas.1100087108. Epub 2011 Mar 14.

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Liquid Crystals / chemistry*
  • Molecular Structure
  • Polymers / chemistry
  • Solutions / chemistry
  • Stereoisomerism*

Substances

  • Polymers
  • Solutions