Parity Violation in Unstirred Crystallization from Achiral Solutions

Chiral symmetry breaking induced by energy dissipation

“…Explaining why this is so is a problem of great current interest. [1][2][3][4][5][6] Advances in the study of chiral symmetry breaking may have an impact in for example the production of efficient and safe medicines, [7][8][9] the use of liquid crystals in biosensors and microlasers, 9 the control of selfassembly for the production of advanced materials 10 and synthetic biological tissues, 11,12 and in providing a deeper understanding of the emergence of life. 5,13 A key question is how self-organised structures are formed from the directed and selective self-assembly of enantiomeric constituents arising from chiral symmetry breaking that takes place outside of equilibrium and, therefore, in the presence of energy dissipation.…”

“…Experiments have shown that the actuation of external factors such as polarised light, 14 shearing, 15,16 temperature gradients 17 and in general external forces driving the system out of equilibrium can lead to a significant disproportion in the concentrations of the homochiral structures (enantiomers) or even prevent their formation. 3,7 In order to reproduce the experimental observations and to be able to identify optimal conditions for the intensification of the phenomenon several kinetic models considering different mechanisms have been proposed. 4,6 Considering the nonequilibrium thermodynamics of the chiral symmetry breaking through the entropy production could be useful to understand also the role of energy dissipation in the process.…”

“…Chiral symmetry breaking in the NaClO 3 crystallisation process has been the subject of much interest in recent years. 4,6,7,18 Experiments consisting of evaporating the solvent to obtain NaClO 3 crystals, 15 performed by stirring the sample, showed the existence of a disproportion in the concentrations of both enantiomeric crystals of NaClO 3 . When these experiments were performed without stirring, the concentrations of both enantiomers were found to be similar.…”

“…Evaporation experiments also showed a disproportion of enantiomers in the absence of stirring but at low supersaturation of salt. 7 These experiments displayed chiral symmetry breaking when the process takes place out of equilibrium, measuring the enantiomeric excess only at the end of crystallisation without providing information on the enantiomeric excess as a function of time. In these experiments, aliquots are drawn periodically, which causes the collected samples to denature as the crystals are not in contact with the system under non-equilibrium conditions.…”

“…In these experiments, aliquots are drawn periodically, which causes the collected samples to denature as the crystals are not in contact with the system under non-equilibrium conditions. 6,7 It is therefore crucial to consider the transient dynamics of the crystallisation process and to measure the in situ populations in order to understand the role of energy dissipation in chiral symmetry breaking.…”