Finely Controlled Stepwise Engineering of Pore Environments and Mechanistic Elucidation of Water-Stable, Flexible 2D Porous Coordination Polymers

Two porous coordination polymers (PCPs) with different topologies (NTU‐19: sql and NTU‐20: dia) underwent finely controlled, stepwise crystal conversions to yield a common water‐stable, flexible 2D framework (NTU‐22: kgm). The crystal conversions occurred directly at higher temperature via the 3D intermediate (NTU‐21: nbo), which could be observed at lower temperature. The successful isolation of the intermediate product of NTU‐21, characterization with in situ PXRD and UV/Vis spectra were combined with DFT calculations to allow an understanding of the dynamic processes at the atomic level. Remarkably, breakthrough experiments demonstrate NTU‐22 with integral structural properties allowed significant CO₂/CH₄ mixture separation.