Evaluating chiral separation interactions by use of diastereomeric polymeric dipeptide surfactants

Poly sodium N-undecyl leucine-leucine (poly SULL) is used as a diagnostic t ool to investigate chiral molecular interactions via electrokinetic chromat ography (EKC). Poly SULL has two chiral centers which are defined by two as ymmetric carbons. Each chiral center of poly SULL can have two possible con figurations (D or L), Consequently, four different optical configurations a re possible within the surfactant molecule (L-L, D-D, L-D, and D-L). In thi s study, five chiral analytes of various charge states and hydrophobicities were used to investigate the role of electrostatic interactions and hydrop hobicity on chiral recognition with polymeric dipeptide surfactants, These studies lead to a proposed hypothesis for interaction of the analytes with dipeptide surfactants. The hypothesis was tested and the contribution of th e double chiral centers to this interaction was evaluated by use of two dip eptide surfactants in which one chiral amino acid is replaced by an achiral amino acid glycine, i.e., poly sodium N-undecyl L-leucine-glycine (poly L- SULG) and poly sodium N-undecyl L-glycine-leucine (poly L-SUGL). The result s reported here provide new insights into the mechanism for chiral recognit ion of select chiral analytes by use of polymeric chiral surfactants.