Molecular model for chirality phenomena

Latinwo, Folarin; Stillinger, Frank H.; Debenedetti, Pablo G.

doi:10.1063/1.4964678

Cited by 23 publications

(42 citation statements)

References 59 publications

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“…These fluids form conglomerates which are capable of strong chirality amplification eventually leading to homogeneous chirality. Especially the observation of spontaneous chiral segregation in isotropic liquids provided a strong boost for the conformational chirality hypothesis, which is also supported by recent simulation work [114][115][116]. However, chirality synchronisation in the fluid state requires cooperativity, i.e.…”

Section: Discussionsupporting

confidence: 58%

“…In contrast, it is usually argued that in the liquid state the energetic difference between the conformers is too small to give rise to any significant bias of molecular conformations and that the entropy of mixing disfavours enantiomeric segregation [36,85,105]. However, there is simulation work suggesting that spontaneous synchronisation of the helix sense of helical conformers ('ferrochirality') is possible in polymers [114], as well as in liquids [115,116], provided that the molecules are transiently chiral (see for example compound 4 in Figure 9(a)). Chirality synchronisation was previously suggested as origin of chirality in some nematic phases of bent-core molecules [84] though it turned out later that in this case director rotation by surface pinning of the nematic director appears to be more important (see Section 9) [117,118].…”

Section: Chirality Synchronisation In Mirror-symmetry Broken Isotropimentioning

confidence: 99%

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Mirror symmetry breaking in liquids and liquid crystals

Tschierske

2018

Liquid Crystals

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In the recent two decades liquid crystal science has contributed significantly to the understanding of mirror symmetry breaking and spontaneous emergence of chirality in fluids. This account tries to summarise the current state of understanding of mirror symmetry breaking in the liquid and liquid crystalline mesophases, ranging from isotropic liquids, via cubic, columnar and tetragonal SmQ phases of polycatenar compounds, the twist bend nematic phases of bent dimesogens to the heliconical and conglomerate type smectic phases of bent-core mesogens. Especially, the importance of dynamic chirality synchronisation of molecular conformers, cooperativity, helical superstructures, layer chirality, network formation, as well as chiral and achiral surface effects is discussed. At the end the transition from local to absolute symmetry breaking, chirality amplification and the relevance for the emergence of uniform chirality in prebiotic fluids and biosystems are considered. Dynamic Mirror Symmetry Breaking Transiently chiral molecules Cooperativity Super structural chirality Chirality synchronisation in fluids Network connectivity

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Section: Discussionsupporting

confidence: 58%

Section: Chirality Synchronisation In Mirror-symmetry Broken Isotropimentioning

confidence: 99%

Mirror symmetry breaking in liquids and liquid crystals

Tschierske

2018

Liquid Crystals

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“…A similar case is the symmetric phase separation of stereoisomers. A recent simulation study [94] One of the arguments in favor of the discrete approach is the direct computation of the equilibrium number of molecules involved in alternative states in several simulated water-like models. The fractions of molecules involved in the high-density structure and in the low-density structure at various temperatures and pressures have been computed for the ST2 [95], TIP4P/2005 [96] and mW [66,97] models.…”

Section: B Is Landau Theory Sufficient To Unify Different Polyamorphmentioning

confidence: 99%

Thermodynamics of Fluid Polyamorphism

et al. 2018

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"Fluid polyamorphism" is the existence of different condensed amorphous states in a single-component fluid. It is either found or predicted, usually at extreme conditions, for a broad group of very different substances, including helium, carbon, silicon, phosphorous, sulfur,tellurium, cerium, hydrogen and tin tetraiodide. This phenomenon is also hypothesized for metastable and deeply supercooled water, presumably located a few degrees below the experimental limit of homogeneous ice formation. We present a generic phenomenological approach to describe polyamorphism in a single-component fluid, which is completely independent of the molecular origin of the phenomenon. We show that fluid polyamorphism may occur either in the presence or the absence of fluid phase separation depending on the symmetry of the order parameter. In the latter case, it is associated with a second-order transition, such as in liquid helium or liquid sulfur. To specify the phenomenology, we consider a fluid with thermodynamic equilibrium between two distinct interconvertible states or molecular structures. A fundamental signature of this concept is the identification of the equilibrium fraction of molecules involved in each of these alternative states. However, the existence of the alternative structures may result in polyamorphic fluid phase separation only if mixing of these structures is not ideal. The two-state thermodynamics unifies all the debated scenarios of fluid polyamorphism in different areas of condensed-matter physics, with or without phase separation, and even goes beyond the phenomenon of polyamorphism by generically describing the anomalous properties of fluids exhibiting interconversion of alternative molecular states.Comment: 56 pages, including 39 pages of main text with 7 figures and 117 references, and 17 pages of supplemental material with 12 figures and 19 reference

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“…[9][10][11] Despite much research activity, no definitive answers to these questions have been found. [12][13][14][15][16][17][18][19][20][21] In principle, thermodynamics dictates that the crystal with the lowest free energy prevails in equilibrium. Studies of chiral molecules a) Electronic mail: michael.gruenwald@utah.edu have shown, however, that thermodynamics alone cannot explain the bias towards racemic crystals observed in experiments.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Interactions Promote Crystallization and Spontaneous Resolution of Chiral Molecules

Carpenter¹,

Grünwald

2019

Preprint

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Predicting the crystallization behavior of solutions of chiral molecules is a major challenge in the chemical sciences. In this paper, we use molecular dynamics computer simulations to study the crystallization of a family of coarse-grained models of chiral molecules with a broad range of molecular shapes and interactions. Our simulations reproduce the experimental crystallization behavior of real chiral molecules, including racemic and enantiopure crystals, as well as amorphous solids. Using efficient algorithms for the packing of shapes, we enumerate millions of low energy crystal structures for each model and analyze the thermodynamic landscape of polymorphs. In agreement with recent conjectures, our analysis shows that the ease of crystallization is largely determined by the number of competing polymorphs with low free energy. We find that this number, and hence crystallization outcomes, depend on molecular interactions in a simple way: Strongly heterogeneous interactions across molecules promote crystallization and favor the spontaneous resolution of racemic mixtures.

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Molecular model for chirality phenomena

Cited by 23 publications

References 59 publications

Mirror symmetry breaking in liquids and liquid crystals

Mirror symmetry breaking in liquids and liquid crystals

Thermodynamics of Fluid Polyamorphism

Heterogeneous Interactions Promote Crystallization and Spontaneous Resolution of Chiral Molecules

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