The Reciprocal Principle of Selectand-Selector-Systems in Supramolecular Chromatography †

Abstract

Abstract:In selective chromatography and electromigration methods, supramolecular recognition of selectands and selectors is due to the fast and reversible formation of association complexes governed by thermodynamics. Whereas the selectand molecules to be separated are always present in the mobile phase, the selector employed for the separation of the selectands is either part of the stationary phase or is added to the mobile phase. By the reciprocal principle, the roles of selector and selectand can be reversed. In this contribution in honor of Professor Stig Allenmark, the evolution of the reciprocal principle in chromatography is reviewed and its advantages and limitations are outlined. Various reciprocal scenarios, including library approaches, are discussed in efforts to optimize selectivity in separation science.

Δ9-cis-Tetrahydrocannabinol: Natural Occurrence, Chirality, and Pharmacology

“…To establish the absolute configuration and the enantiomeric excess of naturally occurring Δ 9 - cis -THC, which could also provide insights into its biogenetic origin (vide infra), we developed an enantioselective analytical method that was able to separate the different Δ 9 - cis -THC enantiomers. To this end, the inverted chirality column approach (ICCA) in normal-phase enantioselective ultra-high-performance liquid chromatography (NP-eUHPLC) was used. , This method is based on the analysis of a chiral compound on two columns having enantiomeric chiral stationary phases, which are, therefore, identical in terms of thermodynamics (retention factor and selectivity) and kinetics (efficiency) but show opposite affinity for enantiomeric compounds, in accordance with the reciprocal principle of selectand–selector systems . Thus, a column switch will result in inverted retention times for a pair of enantiomers, making it possible to identify enantiomers and evaluate enantiomeric excesses even when only one enantiomer of a chiral compound is available.…”

“…Synthetic (−)-Δ 9 - cis -THC and (±)-Δ 9 - cis -THC were prepared according to previously published methods, and standard solutions thereof were prepared in acetonitrile (0.4 mg/mL). , Extracts of two cannabis fiber hemp strains (Kompolti and CRA_05 Fibranova) were purified by preparative thin-layer chromatography (Merck silica gel 60 F254 TLC glass plates, visualized with 254 nm light and cerium ammonium molybdate solution followed by heating), isolating the (±)-Δ 9 - cis -THC-containing fraction ( R f = 0.23, hexanes/ethyl acetate, 15:1). Solutions of purified extracts were prepared in acetonitrile (1.4–1.6 mg/mL).…”

Recent studies of docking and molecular dynamics simulation for liquid‐phase enantioseparations

“…Finally, it is worth noting that knowledge of chiral recognition mechanisms allows researchers to improve selector‐selectand system performance with the aim of optimizing selectivity , all the while paving the way to emerging fields of supramolecular separation science like chiral sensing and other chiral surface related recognition phenomena .…”

Advanced Development of Supercritical Fluid Chromatography in Herbal Medicine Analysis

“…The Gasparrini group [39] utilized a UHPC-(S, S)-Whelk-O1 column and a UHPC-(R, R)-Whelk-O1 column for the enantio-and chemo-selective separation of phytocannabinoids by UHPSFC. The method was based on the "Inverted Chirality Columns Approach" (ICCA) according to the reciprocal principle [40]. The elution order of the enantiomers was reversed by switching two chiral columns with the same SO and opposite configuration.…”