Kinetics and Thermodynamics of Efficient Chiral Symmetry Breaking in Nearly Racemic Mixtures of Conglomerate Crystals

The remarkable evolution of homochirality in Viedma-type conversions, which typically start from racemic or nearly racemic mixtures of D and L conglomerate crystals, is examined using dispersive kinetic models. One such model for nucleation rate-limited phase transformations is found to describe well the sigmoidal (S-shaped) conversion transients of those processes better than both the classical first-order (simple exponential) mechanism proposed in the current literature and the JMAEK (Avrami) equation traditionally used to model nucleation-and-growth processes. That finding is discussed in light of the secondary nucleation observed in similar, Kondepudi-type conversions as well as the recently proposed mechanisms of attrition-enhanced Ostwald ripening and solution phase racemization.