6,6′-Dinitrobiphenyl-2,2′-dicarboxylic acid ionically bonded to aminopropyl silica: New axially chiral phase of C 2 symmetry for high-performance liquid chromatographic separation of enantiomeric amino alcohol derivatives

Abstract

( R)-(+)-6,6′-Dinitrobiphenyl-2,2′-dicarboxylic acid, ionically bonded to 3-aminopropylsilanized silica (CSP 1), is the first ionically bonded axially chiral phase of C 2 symmetry. The phase is specifically efficient for the separation of a wide range of enantiomeric vicinal benzamido alcohols, whether open-chain, cyclic or polycyclic. To assess the steric and polar effects of the 6,6′-substituents, the performance of CSP 1 is compared with that of the analogous (but less effective) phase CSP 2, based on ( S)-(+)-6,6′-dimethylbiphenyl-2,2′-dicarboxylic acid. Some conclusions about the relation between the separation effectivity and the analyte structure, as well as about the factors involved in the chiral recognition process, are given.