Porous metal–organic frameworks have emerged to resolve important challenges of our modern society, such as CO₂ sequestration. Zeolitic imidazolate frameworks (ZIFs) can undergo a glass transition to form ZIF glasses; they combine the liquid handling of classical glasses with the tremendous potential for gas separation applications of ZIFs. Using millimetre-sized ZIF-62 single crystals and centimetre-sized ZIF-62 glass, we demonstrate the scalability and processability of our materials. Further, following the evolution of gas penetration into ZIF crystals and ZIF glasses by infrared microimaging techniques, we determine the diffusion coefficients and changes to the pore architecture on the ångström scale. The evolution of the material on melting and processing is observed in situ on different length scales by using a microscope-coupled heating stage and analysed microstructurally by transmission electron microscopy. Pore collapse during glass processing is further tracked by changes in the volume and density of the glasses. Mass spectrometry was utilized to investigate the crystal-to-glass transition and thermal-processing ability. The controllable tuning of the pore diameter in ZIF glass may enable liquid-processable ZIF glass membranes for challenging gas separations.

Cyclic carbonates are important compounds for the synthesis of biocompatible polymers and linear dialkyl carbonates, as well as solvents and electrolytes. We report here the synthesis of such compounds from easily accessible starting materials with carbon dioxide as a C1 source and caesium carbonate as the base. This new methodology is able to yield 5- and 6-membered cyclic carbonates very efficiently in a green manner.