Manometric real-time studies of the mechanochemical synthesis of zeolitic imidazolate frameworks

We demonstrate a simple 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 directly from powder X-ray diffraction data. We also show that the formation of the carbonate phase may be prevented by using excess ligand, enabling the rational development of first design leading to completely solvent-free and quantitative mechanochemical formation of ZIF-8 on a 90 gram scale, with excess ligand removed by sublimation.