High-performance liquid chromatography enantioseparation of polyhalogenated 4,4’-bipyridines on polysaccharide-based chiral stationary phases under multimodal elution

摘要

An investigation on the high-performance liquid chromatography enantioseparation of 12\udpolyhalogenated 4,4-bipyridines on polysaccharide-based chiral stationary phases is described.\udThe overall study was directed toward the generation of efficient separations in\udorder to obtain pure atropisomers that will serve as ligands for building homochiral metal\udorganic frameworks. Four coated columns—namely, Lux Cellulose-1, Lux Cellulose-2, Lux\udCellulose-4, and Lux Amylose-2—and two immobilized columns—namely, Chiralpak IC\udand IA—were used under normal, polar organic, and reversed-phase elution modes. Moreover,\udChiralcel OJ was considered under normal-phase and polar organic conditions. The effect of the chiral selector and mobile phase composition on the enantioseparation, the enantiomer elution order and the beneficial effect of nonstandard solvents were studied. The effect of water in the mobile phase on the enantioselectivity and retention was investigated and retention profiles typical of hydrophilic interaction liquid chromatography were observed. Interesting phenomena of solvent-induced enantiomer elution order reversal occurred under normal-phasemode. All the considered 4,4-bipyridines were enantioseparated at the multimilligram level.