Renewable sources from plants as the starting material for designing new terpene chiral ionic liquids used for the chromatographic separation of acidic enantiomers

Abstract

Synthesis of cheap and natural resources is an important topic in green chemistry. For that reason, new chiral ionic liquids (CILs) containing a bicyclic terpene moiety were designed and prepared from renewable plant resources. The synthesis route was comprehensively described, especially a specific type of Menschutkin reaction, which gives high energy efficiency during the process. The physicochemical characteristics of the obtained chiral salts, including the spectral properties, melting point, crystal shape, specific rotation and solubility in various solvents were examined. The study presents the effect of new chiral ionic liquids as mobile phase additives on the chiral recognition of acidic enantiomers on a teicoplanin-based chiral stationary phase (CSP). Based on the van't Hoff relationships, the thermodynamic functions were determined. The plots revealed that the chiral recognition was enthalpy driven. The chiral salts obtained exhibited a synergistic effect with the teicoplanin-based stationary phase in the chromatographic system, enhancing the resolution of acidic enantiomers. Structural task-specific properties of the new terpene-based chiral ionic liquids were confirmed by molecular modeling and docking simulations.