Examination of Structural Changes of Polymeric Amino Acid-Based Surfactants on Enantioselectivity:  Effect of Amino Acid Order, Steric Factors, and Number and Position of Chiral Centers

Abstract

In this study, a large number of polymeric chiral surfactants were examined and their performances in terms of enantiomeric resolution compared for a variety of chiral analytes. The surfactants investigated in this study include all possible dipeptide combinations of the L-form of alanine, valine, leucine, and the achiral amino acid glycine (except glycine-glycine). Also included in this study were the single amino acid surfactants of alanine, valine, and leucine as well as the single chiral center dipeptide surfactant poly(sodium undecyl-L-leucine-beta-alanine) (poly L-SULbetaA). Several different aspects of polymeric dipeptide surfactants, as they pertain to chiral separations, are examined. Some of the factors investigated in this report include the effect of position and number of chiral centers, amino acid order, and steric effects.

Using NMR to Develop Insights into Electrokinetic Chromatography

“…5 H. Therefore, PFG-NMR experiments performed through the collection of 13 C spectra require the application of much larger amplitude gradient pulses, which are beyond the capabilities of most standard NMR equipment.…”

Peer Reviewed: Molecular Micelles: Novel Pseudostationary Phases for CE

“…Very recently, Billiot and Warner used 19 polymeric surfactants to study the effect of amino acid order on the enantiomeric resolution of (±)BNA, which is structurally similar to BNP and BOH (41). The effect of amino acid order for BNA followed the same trend as BNP and BOH.…”

“…To further test chiral recognition, Billiot et al computed an estimate of the relative degree of interactions of analytes with a chiral selector (Table 1) (41). The data indicate that BNA and BOH both interact ~25% with the C-terminal amino acid surfactant, whereas ~75% of these interactions occur at the N-terminal position.…”

Effect of Stereochemistry on the Molecular Aggregation of Phenylalanine Dipeptide-type Surfactants

“…For example, they have been used in electrokinetic chromatography for the separation of many chiral compounds [7][8][9][10][11][12][13] . Recently, chiral dipeptide-type surfactants function better in chiral separations than N-acyl amino acid surfactants [14][15][16][17] . This is thought to be because the dipeptide-type surfactant has two amide groups and two amino acid side chains which both play significant roles in chiral recognition.…”