EVALUATION OF PIRKLE-TYPE CHIRAL STATIONARY PHASES BY LIQUID AND SUPERCRITICAL-FLUID CHROMATOGRAPHY - INFLUENCE OF THE SPACER LENGTH AND THE STERIC HINDRANCE IN THE VICINITY OF THE STEREOGENIC CENTER

The scope of applications of novel chiral stationary phases (CSPs) der ived from (S)-phenylalanine or (R)-phenylglycine and bearing a long sp acer in normal-phase liquid chromatography is reviewed with regard to the similar corresponding commercially available brush-type CSPs. The parameters studied were the spacer length and the steric hindrance in the vicinity of the stereogenic centre. The direct separation of beta- blockers in supercritical fluid chromatography (SFC) was also carried out in order to elucidate the influence of the steric decompression. T he chromatographic properties of one of the novel CSPs and the commerc ially available CSP ChyRoSine-A, exhibiting both a long spacer and a w eak steric hindrance in the vicinity of the stereogenic centre, were c ompared. The design and synthesis of three novel CSPs derived from phe nylalanine or phenylglycine and starting from the concept of ChyRoSine -A allowed an optimized CSP to be proposed. This CSP possesses both re duced steric hindrance in the vicinity of the stereogenic centre and a long spacer. Its main advantage is that it combines the fields of app lication of various CSPs (DNBPG, ChiraChrom A1, ChyRoSine-A). In addit ion, this CSP allows the resolution of beta-blockers, where both DNBPG and ChiraChrom A1 fail.