Mechanistic Dissymmetry between Crystal Growth and Dissolution Drives Ratcheted Chiral Amplification.

Complete chiral amplification of the solid phase arises when mixtures of self-sorting enantiopure crystals undergo cycles of crystal growth and dissolution under solution-phase racemizing conditions. However, despite extensive studies and widespread use, the mechanism underlying such crystallization-induced deracemization remains insufficiently understood, hindering its optimization and broader application. Here, we experimentally dissect the individual contributions of crystal growth and dissolution and use a mass-balance to expose crystal dynamics. Regardless of the racemization rate, we always find a dissymmetry between the growth and the dissolution of the enantiomer populations. These experiments suggest that a fundamental difference between the mechanisms of crystal growth and dissolution enables a ratchet effect that drives chiral amplification. These insights advance our understanding of chiral crystallization mechanisms and provide guidance for optimizing crystallization-induced deracemizations, particularly by separately optimizing growth and dissolution steps to maximize the chiral amplification and deracemization efficiency.