Preparation and Application of Aza-15-crown-5-capped Methylcalix[4]resorcinarene-Bonded Silica Particles for Use as Chiral Stationary Phase in HPLC

Abstract

Aza-15-crown-5-capped (3-(C-methylcalix[4]resorcinarene)-2-hydroxypropoxy)-propylsilyl (MCR-HP)-appended silica particles (15C5-MCR-HPS), a new type of substituted C-methylcalix[4]resorcinarene (MCR)-bonded chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC), have been synthesized by reaction of bromoacetate-substituted MCR-HPS with excessive aza-15-crown-5 in anhydrous acetonitrile in the presence of potassium carbonate. The bonded phase 15C5-MCR-HPS is characterized by elemental analysis and further evaluated by separating several disubstituted benzenes and some chiral drug compounds in HPLC. The new CSP has a chiral selector with two recognition sites: 15-crown-5 and MCR-HP, which can provide cooperative multiple interactions with solutes to enhance chiral recognition and to improve chromatographic separation. The chromatographic evaluation results show that 15C5-MCR-HPS has excellent selectivity for the separation of aromatic positional isomers and enantiomers of some chiral compounds under multiple-mode mobile phase conditions including normal phase, reversed phase, and polar organic mobile phase conditions.