Mechanically Stable Micrometric Particles by Spray-Drying of Metal Organic Framework Nanocrystals as a Packing Medium for Chiral Chromatography

Current stationary phases used in chiral high-performance liquid chromatography (HPLC) mainly rely on the use of functionalized polysaccharides. They allow efficient separation of many chiral mixtures, but their cost remains excessively high. The use of metal organic frameworks (MOFs) as stationary phases has been investigated within the past decade, but low column efficiency and excessive column backpressure have often been reported as a result of the irregular shape, submicrometer, and wide size distribution of the MOFs particles. Here, we present a tunable platform of a pure MOF chiral stationary phase for chromatography through the functionalization of MIP-206(Zr) nanocrystals with specific affordable chiral groups, shaped through spray-drying as mechanically stable micrometric particles. MIP-206(Zr) is a highly tunable zirconium oxocluster-based mesoporous solid built with substituted feedstock-derived isophthalic acids (IPA) whose large 1D pores (2.6 nm) offer an ideal platform for chromatographic separations. It has been functionalized through a water-stable postsynthetic modification with camphorsulfonic acid (camphor sulfonic acid (CSA)) or camphoric acid. The chiral MOFs nanocrystals have then been shaped by spray-drying into “doughnut-like” microparticles and packed into HPLC columns. The MIP-206/CSA column demonstrated a separation of carvone enantiomers with a promising selectivity of more than 1.2.