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

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)(H2O)(2)](4+) (Hade=adenine) and GeF62- anions. The framework not only shows permanent porosity, but also exhibits efficient separation performance of C2H2/C2H4 at room temperature. More interestingly, its crystal structure could be irreversibly transformed into isostructural counterpart HOF-ZJU-101 by ion exchange in the SiF62- containing solution, evidenced by multiple characterization techniques including gas sorption measurements, F-19 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.

Automated summary

In this study, a stable hydrogen-bonded metallotecton framework (HOF-ZJU-102) was reported, demonstrating permanent porosity and efficient separation performance of C2H2/C2H4 at room temperature. Through ion exchange mechanism, the collapsed HOF-ZJU-102 could be transformed into HOF-ZJU-101 and restored in a salt solution.