title: Chiroptical study of chiral discrimination by amino acid based ionic liquids.
abstract: The chiral discrimination ability of amino acid based chiral ionic liquids is studied using chiroptical luminescence techniques. A racemic mixture of dissymmetric europium tris(2,6-pyridinedicarboxylate) complexes are dissolved in five chiral ionic liquids, including l- and d-alanine methyl ester bis(trifluoromethanesulfonimide), l-leucine methyl ester bis(trifluoromethanesulfonimide), l-proline methyl ester bis(trifluoromethanesulfonimide), and tetrabutylammonium l-alanate. Circularly polarized luminescence spectra are measured for the samples over the 283-323 K temperature range. Analysis of the spectroscopic results shows that the amino acid methyl ester chiral ionic liquids show discrimination with a preference (handedness) that corresponds to the stereoisomer (l- vs d-). Most of the chiral ionic liquids show enthalpically dominated discrimination, but l-leucine methyl ester bis(trifluoromethanesulfonimide) shows entropically dominated chiral discrimination.
authors.affiliation: Department of Chemistry, Butler University , 4600 Sunset Avenue, Indianapolis, Indiana 46208, United States.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Kroupa
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Brown
authors.forename: Laurel M
authors.initials: LM
authors.lastname: Heckman
authors.forename: Todd A
authors.initials: TA
authors.lastname: Hopkins
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D008163:Luminescent Measurements; D008958:Models, Molecular; D015394:Molecular Structure
chemical_list: D000596:Amino Acids; D052578:Ionic Liquids