Molecular insights into enantioselective separation of λ-cyhalothrin: a theoretical investigation

Abstract

λ-Cyhalothrin (CLT), a widely employed pyrethroid insecticide for pest control, is typically marketed as a racemate, akin to many other pesticides. It has been recognized that optical isomers may exhibit distinct biological activity and toxicity, prompting the burgeoning demand for more efficient separation methods to isolate these isomers. In this study, we employed a theoretical approach to unravel the chiral recognition mechanisms governing the interaction between a polysaccharide-derived stationary phase and the λ-cyhalothrin. Density functional theory calculations were utilized to glean structural and energetic information, enabling the elucidation of the observed chiral discrimination and enantiomeric elution order from prior HPLC experiments. Our analysis pinpointed the critical role of hydrogen bonding and π-π stacking interactions in dictating the relative stability of the diastereomeric complexes formed between the λ-cyhalothrin enantiomers and the chiral selector.