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Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes
Published on: August 16, 2018
Enantioselective separations using chiral supported liquid crystalline membranes
Sangil Han1, Feras Rabie, Eva Marand
1School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
Chirality
|May 15, 2012
Summary
Supported liquid crystalline membranes selectively separate R-enantiomers using cholesteric liquid crystals (LCs). Dopant type and concentration influence enantioselectivity and permeability in chiral separations.
Area of Science:
- Materials Science
- Chemical Engineering
- Separation Science
Background:
- Liquid crystals (LCs) exhibit unique phase behaviors and anisotropic properties.
- Chiral separation is crucial in pharmaceuticals and fine chemicals.
- Supported liquid crystalline membranes offer tunable selectivity for chiral molecules.
Purpose of the Study:
- To develop and characterize supported liquid crystalline membranes for enantioselective separation.
- To investigate the effect of dopants and membrane structure on chiral recognition.
- To understand the transport mechanisms of enantiomers in liquid crystalline phases.
Main Methods:
- Impregnation of porous cellulose nitrate supports with liquid crystal mixtures (5CB doped with COC, CN, or CC).
- Fabrication of porous and nonporous supported liquid crystalline membranes.
- Evaluation of enantioselectivity and permeability for R-phenylglycine and R-1-phenylethanol.
Main Results:
- Membranes showed selectivity for R-enantiomers due to interactions with the left-handed cholesteric phase.
- Selectivity decreased with pore diameter, while permeability increased for phenylglycine and 1-phenylethanol in 5CB/CN membranes.
- Enantioselectivity for 1-phenylethanol was higher in cholesteric phases (e.g., 5CB/COC, 5CB/CN) compared to isotropic or nematic phases.
- Enantioselectivity plateaued around 17 mol% dopant concentration.
Conclusions:
- Supported cholesteric liquid crystalline membranes are effective for enantioselective separations.
- Membrane structure, dopant properties, and concentration significantly impact chiral separation performance.
- The study provides insights into the molecular interactions governing enantioselective transport in liquid crystalline materials.
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