Chemistry Seminar: Mohan Srinivasarao, Georgia Tech

Mohan Srinivasarao Georgia Institute of Technology Emergence of Chiral Structures in Achiral Lyotropic Liquid Crystals Host: Bruce Armitage Friday, September 11th, 2026 12:30 p.m. Mellon Institute Conference Room 348 Abstract: Crystallization of tartrates by Pasteur provided the first glimpse of spontaneous mirror-symmetry breaking, and that led to the foundation of stereochemistry as a discipline. A consequence of mirror-symmetry breaking is optical activity, and since the time of its discovery by Biot in the early 1800s, has fascinated scientist. Since those early studies, the appearance of macroscopic chirality from both chiral and achiral molecules has been on interest. In this talk, we discuss the appearance of macroscopic chiral structures from a class of liquid crystals, referred to as lyotropic liquid crystals, under various conditions. When confined to a cylindrical geometry with planar boundary conditions, the presumed ground state of a nematic fluid corresponds to that of an axial configuration, where the director, free of deformations, lies along the long axis of the cylinder. However, upon confinement of lyotropic chromonic liquid crystals in cylindrical geometries, we uncover a surprising ground state corresponding to a doubly twisted director configuration. The stability of this ground state, which involves significant director deformations, can be rationalized by the saddle-splay contribution to the free energy. It will be shown that sufficient anisotropy in the elastic constants drives the transition from a deformation-free ground state to a doubly twisted structure, and results in spontaneous reflection symmetry breaking with equal propensity for either handedness. Enabled by the twist angle measurements of the spontaneous twist, we determine the saddle-splay elastic constant for chromonic liquid crystals. I will also discuss the path to a monodomain or a single crystal, if you will, of chrominc liquid crystals confined to a rectangular capillary e