Generation of covalently functionalized hierarchical IRMOF-3 by post-synthetic modification

Here, we report the synthesis and characterization of covalently functionalized hierarchical IRMOF-3 having micro-/meso-pores and macroscopic trenches. Functionalized hierarchical IRMOF-3 was synthesized by an etching process by the protons released when the amine groups in the structure react with cyanuric chloride. This etching process is found to be self-limited due to the diffusion limitation of cyanuric chloride. X-ray diffraction confirms that the crystal structure of the MOF is maintained during the modification reaction and N2 isotherms show the presence of micro- and meso-porosity in IRMOF-3 after modification. The microstructure of hierarchical IRMOF-3 after being modified with cyanuric chloride was studied using various characterization techniques such as optical/electron microscopy, infrared spectroscopy, thermal gravimetric analysis, and X-ray photoelectron spectroscopy. Preliminary CO2 adsorption by post-synthetically modified hierarchical IRMOF-3 is promising with an improved sorption capacity despite having a reduced surface area.

Graphical abstract.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► IRMOF-3 is post-synthetically modified with cyanuric chloride. ► Protons generated due to the reaction between amines and cyanuric chloride create a hierarchical pore structure. ► The etching process is self-limited due to the diffusion limitations of cyanuric chloride. ► Hierarchical IRMOF-3 has a core–shell microstructure. ► Despite reduced surface area, IRMOF-3 shows slightly improved CO2 adsorption as compared to unmodified IRMOF-3.