High performance liquid chromatography on calixarene-bonded silica gels.: III.: Separations of cis/trans isomers of proline containing peptides

The liquid chromatographic behavior of p-tert-butylcalix[n]arene (n = 4, 5, 6, and 8) for the separation of cis/trans peptide bond isomers of proline-containing peptides is studied to demonstrate the chromatographic selectivity of calixarene stationary phases. The results are compared with the elution patterns obtained on RP18 and β-cyclodextrin, as well as on a monomeric p-tert-butylphenoxyacetic acid. The chromatographic data are established by rechromatography and 1H-NMR spectroscopy. The results support the assumption that inclusion complexation seems to be a possible separation principle because of the size of the calixarene cavities.