Chiral Recognition Mechanisms in the Direct Resolution of Diol Enantiomers of Some Polycyclic Aromatic Hydrocarbons by High Performance Liquid Chromatography with Chiral Stationary Phases

Abstract

The direct resolution of trans and cis bay region dihydrodiol and tetrahydrodiol enantiomers of benz[a]anthracene and benzo[a]-pyrene, and trans and cis K-region dihydrodiol enantiomers of benz[a]anthracene, 4-methylbenz[a]anthracene, 7-methylbenz[a]anthracene, 7,12-dimethylbenz[a]anthracene, and 3-methylcholanthrene was evaluated by high-performance liquid chromatography using commercially available columns packed with (R)-N-(3,5-dinitrobenzoyl)phenylglycine and (S)-N-(3,5-dinitrobenzoyl)leucine either ionically or covalently bonded to γ-aminopropylsilanized silica. Except benz[a]anthracene trans-5,6-dihydrodiol, the diol enantiomers of other hydrocarbons were all resolved by at least one of the four chiral stationary phases tested. The absolute configurations of enantiomeric diols, whose hydroxyl groups' conformations are restricted due to steric factors, have been established by the exciton chirality circular dichroism method. Based on the experimental results, the mechanisms of some chiral interactions between diol solutes and chiral stationary phases responsible for enantiomeric resolution can be rationalized.