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Enantioselective separations using chiral supported liquid crystalline membranes
Author(s) -
Han Sangil,
Rabie Feras,
Marand Eva,
Martin Stephen M.
Publication year - 2012
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22026
Subject(s) - chemistry , enantioselective synthesis , liquid crystalline , membrane , chirality (physics) , organic chemistry , combinatorial chemistry , nanotechnology , catalysis , phase (matter) , chiral symmetry , biochemistry , materials science , physics , quantum mechanics , quark , nambu–jona lasinio model
Porous and nonporous supported liquid crystalline membranes were produced by impregnating porous cellulose nitrate supports with cholesteric liquid crystal (LC) materials consisting of 4‐cyano‐4′‐pentylbiphenyl (5CB) mixed with a cholesterol‐based dopant (cholesteryl oleyl carbonate [COC], cholesteryl nonanoate [CN], or cholesteryl chloride [CC]). The membranes exhibit selectivity for R ‐phenylglycine and R ‐1‐phenylethanol because of increased interactions between the S enantiomers and the left‐handed cholesteric phase. The selectivity of both phenylglycine and 1‐phenylethanol in 5CB/CN membranes decreases with effective pore diameter while the permeabilities increase, as expected. Phenylglycine, which is insoluble in the LC phase, exhibits no transport in the nonporous (completely filled) membranes; however, 1‐phenylethanol, which is soluble in the LC phase, exhibits transport but negligible enantioselectivity. The enantioselectivity for 1‐phenylethanol was higher (1.20 in 5CB/COC and 5CB/CN membranes) and the permeability was lower in the cholesteric phase than in the isotropic phase. Enantioselectivity was also higher in the 5CB/COC cholesteric phase than in the nematic phase of undoped 5CB (1.03). Enantioselectivity in the cholesteric phase of 5CB doped with CC (1.1), a dopant lacking hydrogen bonding groups, was lower than in the 5CB/COC phases. Finally, enantioselectivity increases with the dopant concentration up to a plateau value at approximately 17 mol%. Chirality 24:519–525, 2012 . © 2012 Wiley Periodicals, Inc.