Chirality is an essential phenomenon underlying biological evolution and pharmaceutical industrial syntheses. Understanding the chiral symmetry-breaking phase transitions exhibited by many chiral molecules provides basic insights for both of these important subjects. In this work, we have performed molecular dynamics simulations to investigate the vapor-liquid and chirality-induced liquid-liquid phase transitions using a flexible 3-dimensional four-site (tetramer) chiral molecular model developed by Latinwo <i>et al</i>. (J. Chem. Phys. 145, 154503, 2016). By constructing a temperature-density-composition phase diagram, we show that in the high temperature regime, the system behaves as an effective L/D binary mixture and kinetically exhibits a metastable liquid-liquid phase separation due to the insufficient L/D intermolecular interconversion rate as opposed to the time scale of diffusive system relaxation. The vapor-liquid coexistence region exists below the liquid-liquid critical locus where the system contains vapor-liquid-liquid phase co-existence. While the vapor phase remains achiral, the liquid phase undergoes chiral symmetry breaking and eventually undergoes infrequent interconversions between the L-rich and D-rich states. These simulation results provide basic thermodynamic insights for generally understanding many-body chiral phenomena, including their phase transition consequences.

Vapor-liquid-liquid phase transitions of a chiral tetramer model

ACS Spring Meeting 2021

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