Chiral Symmetry Breaking of Sodium Chlorate in a Taylor Vortex Flow

This study investigated the initial chiral symmetry breaking (CSB) of sodium chlorate in a Taylor vortex flow (TVF). The TVF was generated in the gap between two coaxial cylinders by rotating the inner cylinder of the Couette–Taylor (CT) crystallizer. Our findings demonstrated that this periodic fluid motion of TVF enabled highly asymmetric initial nucleation of enantiomeric crystals, leading to achieving up to 100% crystal enantiomeric excess (CEE) in the induction period. This remarkable outcome was observed in various vortex flow regimes, including laminar Taylor vortex, wavy-vortex, double-periodic wavy-vortex, and turbulent vortex, by varying the rotation speed of the CT crystallizer. The initial CEE was dependent on the supersaturation at the induction period. Therefore, the initial CEE of 100% was reduced to approximately 50% at a high cooling rate and feed concentration. However, this initial CEE value in the CT crystallizer was much higher than that in a mixing tank (MT) crystallizer, where the random turbulent eddy flow (TEF) was generated by the impeller agitation, demonstrating the superior hydrodynamic effect of TVF on asymmetric enantiomeric nucleation. Our study exhibited the importance of periodic flow patterns in achieving complete initial CSB.