Copper-induced Synthesis of Zinc Imidazolate Metal-Organic Framework (ZIF-8) Crystals and Coatings

Zeolitic imidazolate framework-8 (ZIF-8) is one of the most stable Metal Organic Frameworks currently avail-able, with promising properties in adsorption, separation and catalysis. Herein, we report a method for the rapid production of ZIF-8 crystals at room-temperature from methanolic solutions containing sodium acetate and metal salts. Of the different metal salts tested, copper nitrate presence prompted formation of cubic shaped ZIF-8 crystals within 5 min. Derived from this finding, an adaption of the synthesis route was implemented over copper foils and copper based metallic/non-metallic substrates, which yielded high quality shape-and size -controlled ZIF-8 crystal coatings. The outcomes also revealed a significant impact of sodium acetate as modu-lator and of copper ions released in the reaction media as triggering agent/co-modulator. Together these chemical species are understood to be involved in a multitude of coordination complex formation and depro-tonation equilibria, thus largely determining the ZIF-8 crystal morphology and growth, especially near the copper releasing sites. Overall, this work presents an important platform for rapid and controlled synthesis of ZIF-8 crystals and coatings over metallic/non-metallic substrates, which can be adapted for advanced applica-tions such as device integration.