Novel approach to the study of the chiral discrimination mechanism in a series of dansyl amino acids.
With poly(octadecylsiloxane) as the liquid chromatographic stationary phase, phosphate buffer as the mobile phase, a series of D- and L-dansyl amino acids as solutes, and beta-cyclodextrin as the chiral selector, a study was conducted of the hydrophobic effect on both the solute complexation with the chiral selector and chiral discrimination mechanisms by varying the sucrose concentration in the mobile phase and the column temperature. The number of sucrose molecules excluded during the solute complexation with the chiral selector proved to be a good marker of the solute inclusion in the cavity. Gibbs Helmotz parameters delta(deltaH) and delta(deltaS) between D- and L-enantiomers were determined from plots of the logarithm of the intrinsic selectivity versus the reciprocal of the temperature. The results obtained predicted that the enantioselectivity was related to the bulkiness of the solute. This numerical approach is a valuable tool in the exploration of the steric effects implied in the formation of the host-guest complex.
Guillaumie
Y C
YC
Universite de Franche-Comte, Faculté de Médecine et de Pharmacie, Equipe de Chimie Therapeutique-Laboratoire de Chimie Analytique, Besançon, France. yves.guillaume@univ-fcomte.fr
Guinchard
C
C
Tong
T T
TT
Thomassin
M
M
D000596:Amino Acids / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods; D003619:Dansyl Compounds / Q000737:chemistry*; D008956:Models, Chemical; D012833:Siloxanes; D012996:Solutions; D013237:Stereoisomerism; D013395:Sucrose; D013816:Thermodynamics
D000596:Amino Acids; D003619:Dansyl Compounds; D012833:Siloxanes; D012996:Solutions; D013395:Sucrose