Chiral calixarenes as modifiers of stationary and mobile phases in HPLC /

Abstract

The class of basket-shaped macrocyclic compounds known as calix[n]arenes are of interest in chromatography due to their ability to form host/guest complexes. An area of limited exploration has been the use of chiral calixarenes to perform analytical separations of enantiomers. The interest in this work arises from the search for alternatives to cyclodextrins, which are used predominantly in the separation of enantiomeric mixtures. Two approaches using calixarenes are presented here. The first is the use of a synthesized chiral calixarene as a modifier of a reverse phase stationary phase in HPLC; the second is the use of the same calixarene as a modifier of the mobile phase in reverse phase HPLC. Interactions between a non-chiral homologous series of compounds and the synthesized calixarene were determined to take place during both approaches. This was evidenced by the difference in retention times, capacity factors, and asymmetry factors when the synthesized calixarene was used as a modifier.