Effect of impurities on chirality conversion by grinding

A Complex Reaction Network Model for Spontaneous Mirror Symmetry Breaking in Viedma Deracemizations

Attrition-enhanced chiral symmetry breaking in crystals, known as Viedma deracemization, is a promising method for converting racemic solid phases into enantiomerically pure ones under non-equilibrium conditions. However, many aspects of this process remain unclear. In this study, we present a new investigation into Viedma deracemization using a comprehensive kinetic rate equation continuous model based on classical primary nucleation theory, crystal growth, and Ostwald ripening. Our approach employs a fully microreversible kinetic scheme with a size-dependent solubility following the Gibbs-Thomson rule. To validate our model, we use data from a real NaClO3 deracemization experiment. After parametrization, the model shows spontaneous mirror symmetry breaking (SMSB) under grinding. Additionally, we identify a bifurcation scenario with a lower and upper limit of the grinding intensity that leads to deracemization, including a minimum deracemization time within this window. Furthermore, this model uncovers that SMSB is caused by multiple instances of concealed high-order autocatalysis. Our findings provide new insights into attrition-enhanced deracemization and its potential applications in chiral molecule synthesis and understanding biological homochirality.

Conversion of stable crystals to metastable crystals in a solution by periodic change of temperature

Using a Becker-Döring-type model including cluster incorporation, we study the possibility of conversion of stable crystals to metastable crystals in a solution by a periodic change of temperature. At low temperature, both stable and metastable crystals are assumed to grow by coalescence with monomers and corresponding small clusters. At high temperature, a large amount of small clusters produced by the dissolution of crystals inhibits the dissolution of crystals, and the imbalance in the amount of crystals increases. By repeating this process, the periodic temperature change can convert stable crystals into metastable crystals.