The macrocyclic oligosaccharide molecules, cyclodextrins, have played an important role in chiral separations.  Newly discovered members of this class of molecules, called cyclofructans (CF), are unique in that they consist of a crown ether core with pendant fructofuranose units spiro-anellated around the crown in a propeller-like fashion.  They are formed by the enzymatic decomposition of inulin producing three main types of cyclofructan, i.e. CF6, CF7 and CF8 (CFn, where n= number of fructofuranose units).  CF6 possesses an 18-crown-6 core which readily complexes with barium. In this study, cyclofructan based stationary phases have been conditioned with a barium salt solution to afford cationic chiral stationary phases. The barium doped chiral selector afforded increased retention for sulfonate and phosphate containing chiral analytes in the polar organic mode. The increased retention was also enantioselective and chiral separations were obtained using the barium doped columns that were not afforded on the untreated columns. Barium doped native cyclofructan, isopropyl carbamate cyclofructan and R-naphthylethylcarbamate cyclofructan phases were evaluated for evaluated for enantioselectivity towards chiral sulfonic and phosphoric acids. It was determined that each chiral stationary phase bound barium and increased retention for sulfonates and phosphates. Mechanistic and technical aspects of this technique will be further discussed. The developed technique was also applied to a semi-preparative chiral separation of a chiral sulfonic acid.

Enantiomeric separation of chiral phosphates and sulfonates using barium-complexed cyclofructan stationary phases

247th National Meeting (2014)

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