Manometric Real-Time Studies of the Mechanochemical Synthesis of Zeolitic Imidazolate Frameworks

We demonstrate a method for real-time monitoring of mechanochemical synthesis of metal-organic frameworks, by measuring changes in pressure of gas produced in the reaction. Using this manometric method to monitor the mechanosynthesis of the zeolitic imidazolate framework ZIF-8 from basic zinc carbonate reveals an intriguing feedback mechanism in which the initially formed ZIF-8 reacts with the CO₂ byproduct to produce a complex metal carbonate phase, the structure of which is determined from powder X-ray diffraction data. Formation of the carbonate phase may be prevented by using excess ligand, leading to quantitative formation of ZIF-8. This reaction was performed on a 90 g scale, with the excess ligand removed by sublimation.