Coassembling Mesoporous\nZeolitic Imidazolate Frameworks\nby Directed Reticular Chemistry

Conventional microporous zeolitic\nimidazolate frameworks\n(ZIFs)\nface limitations in mass transfer and pore accessibility when dealing\nwith large guest molecules. Here, we describe a technique for the\nsynthesis of mesoporous ZIFs (MesoZIFs) using a strategy we term directed\nreticular chemistry. MesoZIF-8 was prepared through solvent evaporation-induced\ncoassembly of polystyrene-<i>block</i>-poly(ethylene oxide)\n(PS-<i>b</i>-PEO), ZIF-8 building blocks, and acetic acid\n(AcOH), followed by amine-facilitated crystallization of ZIF-8 in\nthe interstices of PS-<i>b</i>-PEO micelles. AcOH prevents\nthe fast coordination of ZIF-8 building blocks, avoiding phase separation\nduring coassembly. The employed amine plays a crucial role in neutralizing\nthe crystallization environment and further deprotonating the 2-methlyimizale\nlinker to coordinate with zinc ions. Ink bottle-shaped mesopores with\ntunable mesopore sizes were created by adjusting the molecular weight\nof PS-<i>b</i>-PEO. Compared to microporous ZIF-8, MesoZIF-8\nexhibited enhanced performance in Knoevenagel condensation reactions\ninvolving large reactants and hydrogen storage capacity. With this\nstudy, we establish an efficient approach for synthesizing MesoZIFs\nwith highly accessible mesopores to enhance ZIF performance in targeted\napplications.