Chiral stationary phases consisting of axially dissymmetric 2′-substituted-1,1′-binaphthyl-2-carboxylic acids bonded to silica gel for high-performance liquid chromatographic separation of enantiomers

Abstract

Seven chiral stationary phases (CSPS) were prepared by bonding axially dissymmetric 2′-substituted-1,1′- binaphthyl-2-carboxylic acids to aminoalkylsilanized silica gels through an amide linkage, and the effect of the 2′-substituents (CN, COOH, CONH 2, CONHEt, CONEt 2 and OCH 3) was investigated for the high-performance liquid chromatographic (HPLC) separation of enantiomers. Among these CSPS, that which had a 2′-carboxyl substituent showed the best performance and efficiently discriminated several enantiomeric amino acids, amines and alcohols as their 3,5-dinitrophenyl derivatives, and biaryls bearing 2,2′-polar substituents, by normal-phase HPLC. Stereoselective π-donor-acceptor interaction and dipole stacking interaction between the CSPs and the analytes seem to play a critical role in the enantioseparation.