Mechanochemistry-assisted linker exchange of metal-organic framework for efficient kinetic separation of propene and propane

Solvent-assisted linker exchange (SALE) is a powerful tool to increase the structural complexity of metal–organic frameworks (MOF) and expand their functionality, while amounts of organic solvent and energy-intensive heating are needed in this process. In this work, we propose a solvent-free and environment-friendly mechanochemistry-assisted linker exchange strategy (MALE) for MOF post-synthetic modification in a green and sustainable manner at room temperature, which is demonstrated by the efficient linker exchange in ZIF-8 (ZIF = Zeolitic imidazolate frameworks) with imidazole-2-formaldehyde (Im-CHO) ligand. Importantly, contrast experiments show that the linker exchange reaction rate of the MALE method is much faster and more efficient than the conventional SALE method. In addition, the versatility of the MALE method is certified by successfully extending to robust UiO-66 (UiO = University of Oslo) and other functional ZIF-8 analogues, including ZIF-8/Br, ZIF-8/CF3, ZIF-8/CH2OH, ZIF-8/Cl, and ZIF-8/Et. Besides, the obtained ZIF-8/CF3 shows a boosting kinetic separation performance for C3H6/C3H8 gas mixtures compared with pristine ZIF-8. This work not only proposes a green, efficient, and solvent-free linker exchange method of MOF, but also develops a potential adsorbent for efficient kinetic separation of C3H6/C3H8 mixtures.