Abstract
We present a model to explain the mechanism behind enantiomeric separation under either shear flow or local rotational motion in a fluid. Local vorticity of the fluid imparts molecular rotation that couples to translational motion, sending enantiomers in opposite directions. Translation-rotation coupling of enantiomers is explored using the molecular hydrodynamic resistance tensor, and a molecular equivalent of the pitch of a screw is introduced to describe the degree of translation-rotation coupling. Molecular pitch is a structural feature of the molecules and can be easily computed, allowing rapid estimation of the pitch of 85 druglike molecules. Simulations of model enantiomers in a range of fluids such as Λ- and Δ-[Ru(bpy)3]Cl2 in water and (R, R)- and (S, S)-atorvastatin in methanol support predictions made using molecular pitch values. A competition model and continuum drift-diffusion equations are developed to predict separation of realistic racemic mixtures. We find that enantiomeric separation on a centimeter length scale can be achieved in hours, using experimentally achievable vorticities. Additionally, we find that certain achiral objects can also exhibit a nonzero molecular pitch.
Highlights
Enantiomers of chiral molecules are non-superposable mirror images with the same structural formula.[1,2] In achiral environments, enantiomers have identical physical and chemical properties, and this prevents separation by classical methods.[2,3,4] For example, crystallization and filtration (separation by solubility),[5] distillation (separation by boiling point)[5] and standard achiral chromatography (separation by interaction with a stationary phase and a solvent)[5] are unable to resolve enantiomers.The current methods to resolve enantiomers are expensive and not universal.[2,3,4,6] These methods typically require changes in synthetic pathways or separation in chiral environments
We develop an explanatory “screw” model for predicting the shear-flow separation of enantiomers using a set of hydrodynamic calculations on the structures of the molecules
From the mirror image property of the translation-rotation coupling tensor (Ξtr), we have discovered that achiral objects can exhibit a non-zero molecular pitch
Summary
Enantiomers of chiral molecules are non-superposable mirror images with the same structural formula.[1,2] In achiral environments, enantiomers have identical physical and chemical properties, and this prevents separation by classical methods.[2,3,4] For example, crystallization and filtration (separation by solubility),[5] distillation (separation by boiling point)[5] and standard achiral chromatography (separation by interaction with a stationary phase and a solvent)[5] are unable to resolve enantiomers.The current methods to resolve enantiomers are expensive and not universal.[2,3,4,6] These methods typically require changes in synthetic pathways or separation in chiral environments. We develop a hydrodynamic framework to rapidly estimate molecular pitches, as well a competition model for the separation of chiral molecules in solution.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
