Evaluation of 2-Chrysenyl and 1-Pyrenyltartramide Derivatives as Chiral Selectors for Enantiomeric Separation on Porous Graphitic Carbon High-performance Liquid Chromatographic Columns

Abstract

Four chiral stationary phases were proposed containing (R,R)-N,N′-isopropyltartramide and (R,R)-N,N′-(3-nitrophenyl)tartramide groups covalently linked to 2-chrysene and 1-pyrene. They were strongly adsorbed on porous graphitic carbon to afford carbon-based chiral stationary phases. The stereoselective properties of these phases were evaluated using high-performance liquid chromatography and the phases were found to be capable of the recognition of aromatic alcohols, binaphthyl analogues, β-blocking agents and anti-inflammatory agents. The addition of ammonium acetate to the mobile phase enhanced the enantioselectivity for some solutes. The influences of the solute structure and the chiral selector structure on chiral recognition were examined. The effect of substituents attached to the tartramide selectors, such as hydroxyl, acetyl and/or nitrobenzene groups, was studied. A low column temperature improved the enantioselective resolution. The stability of the adsorbed stationary phases under the chromatographic conditions (using polar and non-polar solvents) was also investigated.