Katsuhiro Maeda
Kanazawa University, Japan
Title: Elution order switchable chiral stationary phases for HPLC based on switching and memory of helicity in polyacetylenes in the solid state
Biography
Biography: Katsuhiro Maeda
Abstract
Separation of enantiomers by high-performance liquid chromatography (HPLC) is an effective method both for analyzing enantiomer composition of chiral compounds and obtaining pure enantiomers. Although a large number of chiral stationary phases (CSPs) for HPLC have been developed, it is still a challenging issue to switch the elution order of enantiomers under identical chromatographic conditions. Recently, we have found that a polyacetylene derivative bearing 2,2’-biphenol-derived pendants can form a preferable helical conformation in response to the chirality of non-racemic guest compounds, such as 1-phenylethanol (PEA), in the solid state as well as in solution, and the induced preferred-handed macromolecular helicity can be maintained, that is memorized, even after complete removal of the chiral guests. By taking advantage of this unique feature, we have succeeded in developing an unprecedented switchable CSP for HPLC, in which the elution order of the enantiomers can be switched, which will be based on reversible switching and subsequent memory of the macromolecular helicity by the treatment with (R)- and (S)-PEA in the solid state. In order to improve the chiral recognition ability, we synthesized analogous polyacetylene derivatives with ester or carbamate groups as the effective interaction sites and investigated a relationship between the structures of the pendants and the recognition abilities of the polymers. Repetitive switching of the elution order of enantiomers based on the switching of the macromolecular helicity was achieved by immobilizing these polymers onto silica support.