Crystal Structure Transformation in Hydrogen‐bonded Organic Frameworks via Ion Exchange

Abstract Hydrogen‐bonded organic frameworks (HOFs) have emerged as rapidly growing porous materials while established permanent porosities are very fragile and difficult to stabilize due to weak hydrogen‐bonding interactions among building units. Herein, we report a stable hydrogen‐bonded metallotecton framework (termed as HOF‐ZJU‐102) that was constructed through hydrogen‐bonding networks between cationic metal‐organic complexes [Cu 2 (Hade) 4 (H 2 O) 2 ] 4+ (Hade=adenine) and GeF 6 2− anions. The framework not only shows permanent porosity, but also exhibits efficient separation performance of C 2 H 2 /C 2 H 4 at room temperature. More interestingly, its crystal structure could be irreversibly transformed into isostructural counterpart HOF‐ZJU‐101 by ion exchange in the SiF 6 2− containing solution, evidenced by multiple characterization techniques including gas sorption measurements, 19 F NMR spectra, FTIR and EDS. Utilizing such an ion exchange mechanism, the collapsed HOF‐ZJU‐102 could be restored into HOF‐ZJU‐101 by simply soaking in the salt solution.