Template-directed one-pot synthesis of ZIF-11–93 hybrids with continuously variable hydrophobic and hydrogen-bonding synergistic sites and hence tunable adsorptive separation properties

Problems arising from differences in size, shape, and type of two distinct linkers can hamper the direct synthesis of hybrid Zeolite imidazolate frameworks (ZIFs) spanning the full range of linker compositions. We report herein the use of toluene as a template, exploiting its π–π interactions with benzimidazole (bIm) and 4-methyl-5-imidazolecarboxaldehyde (almeIm) linkers, to directly synthesize ZIF-11–93 hybrids covering the entire dual-linker composition range, which show tunable and desirable properties. Experimental results show that ZIF-11–93_22.6, with an appropriate balance of hydrophobic and hydrogen-bonding groups, demonstrates enhanced 2,3-BDO affinity and driving force in aqueous solution, leading to longer breakthrough time, shorter mass-transfer zone, and higher dynamic column adsorption capacity than those of ZIF-11 with a hydrophobic linker and ZIF-93 with a hydrogen-bonding linker. Calculations predict that the hydrophobic/hydrogen-bonding synergistic sites of ZIF-11-93_x hybrids should intensify its interaction with 2,3-BDO in aqueous solution, thereby permitting the effective separation of 2,3-BDO and 1,3-PDO.