Metal-organic frameworks as stationary phases for chiral chromatographic and membrane separations

Nowadays thousands of stable MOF structures are known and investigated for guest-host adsorption in liquid and gas phase. Here, in this review, we focus on the current state-of-art regarding chiral resolution using homochiral MOF structures. Synthesis routes and pore architectures are critically reviewed along with the reported chiral resolution potential for small chiral organics. Besides gas and liquid phase adsorption of racemates, special attention is given to the application of these materials as stationary phases (GC, HPLC) and their use in membrane applications. Current state-of-art clearly illustrates the promise that MOFs hold for chromatographic separations: versatile routes to modification of achiral MOF structures or synthesis of intrinsic chiral pore architecture, tunable pore size and structure, and formulation in beads for packed bed technology or substrate growing for membrane technology. However, it is also clear that, in spite of several initial reports, much work still needs to be done as questions that is, regarding mechanical, thermal, and long term stability of MOF chiral stationary phases, shaping of such MOFs into monodisperse spheres needed to achieve high resolution, compatibility with mobile phases etcetera remain unanswered. (C) 2014 Elsevier Ltd. All rights reserved.