Characterization and Thermodynamic Studies of the Interactions of Two Chiral Polymeric Surfactants with Model Substances:  Phenylthiohydantoin Amino Acids

Abstract

Analytical ultracentrifugation is used for determination of the molecular weights and the sedimentation coefficients of poly(sodium undecanoyl-L-valinate) (PSUV) and poly(sodium undecanoyl-L-threoninate) (PSUT) at different temperatures. Plots of absorbance as a function of radius indicates that both PSUV and PSUT are highly monodispersed. A method for evaluating the partial specific volumes using density measurements is presented. The partial specific volumes of PSUV are slightly higher than those of PSUT. In addition, the temperature dependence of the retention factor in electrokinetic chromatography was used to estimate the enthalpy, the entropy, and the Gibbs free energy of the surfactant/analyte complexes. Five phenylthiohydantoin-DL-amino acids were separated and each enantiomeric pair was completely resolved. Comparison of the thermodynamic values obtained with PSUV vs PSUT using a van't Hoff relationship suggests that PSUT, with a less favorable free energy change (i.e., less negative delta (delta G)), generates a more positive entropy change, hence slightly less chiral resolution.

Chiral recognition of binaphthyl derivatives using electrokinetic chromatography and steady‐state fluorescence anisotropy: Effect of temperature

“…In addition, it should be mentioned that the van't Hoff plot [1] was linear for the enantiomers of BNP. From this plot, thermodynamic values for the enantiomers of this analyte were calculated, according to the procedure reported previously by our group [10]. Enthalpies of 291.3 J/mol for R-BNP and 2106.5 J/mol for S-BNP were obtained.…”

Polymeric alkenoxy amino acid surfactants: IV. Effects of hydrophobic chain length and degree of polymerization of molecular micelles on chiral separation of β-blockers

“…However, the recent use of micelle polymer (aka. molecular micelle or polymeric surfactant) as chiral selector in MEKC has extended the range and applicability of this technique for chiral analysis [6][7][8][9][10][11][12]. In the case of micelle polymers, the hydrocarbon tail of a chiral surfactant is covalently linked.…”

Use of poly(sodium oleyl‐L‐leucylvalinate) surfactant for the separation of chiral compounds in micellar electrokinetic chromatography

“…Therefore, one often uses partial specific volume V (a.k.a V-bar), which is defined as the increase in volume when 1 g of dry solute is dissolved in a large volume of solvent. The V-values are determined by plotting the inverse of the density (1/r) of the solutions as a function of the weight fraction (W) of the polymers according to the following equation [29,37,38], i.e.,…”