Immobilization of metal–organic frameworks on supports for sample preparation and chromatographic separation

Metal–organic frameworks (MOFs) are porous crystalline materials with large surface areas, uniform pore size, and tunable selectivity. In the last few years, the number of analytical applications of MOFs has been growing constantly. However, the direct use of as-synthesized MOFs in packed column format is rather limited for analytical separations because of the small size and non-spherical shape of MOF crystals. In this review, we outline and critically discuss the advantages and limitations of the different methods described to immobilize MOFs into functional supports for analytical separations, including beads, monoliths, and fibers. These methods are based on embedding MOF crystals into functional supports, in situ MOF growth, controlled layer-by-layer MOF growth, or the in situ conversion of immobilized MOF metal oxide precursors. Representative examples of immobilized MOFs for sample preparation and chromatographic separation are overviewed. We also overview recent progress on the use of MOFs as precursors to obtain other functional materials such as layered double hydroxides or porous carbons.