Tuning the Ionicity of Stable Metal-Organic Frameworks through Ionic Linker Installation

The predictable topologies and designable structures of metal-organic frameworks (MOFs) are the most important advantages for this emerging crystalline material compared to traditional porous materials. However, pore-environment engineering in MOF materials is still a huge challenge when it comes to the growing requirements of expanded applications. A useful method for the regulation of pore-environments, linker installation, has been developed and applied to a series of microporous MOFs. Herein, employing PCN-700 and PCN-608 as platforms, ionic linker installation was successfully implemented in both microporous and mesoporous Zr-based MOFs to afford a series of ionic frameworks. Selective ionic dye capture results support the ionic nature of these MOFs. The mesopores in PCN-608 are able to survive after installation of the ionic linkers, which is useful for ion exchange and further catalysis. To illustrate this, Ru(bpy)₃²⁺, a commonly used photoactive cation, was encapsulated into the anionic mesoporous PCN-608-SBDC via ion exchange. Photocatalytic activity of Ru(bpy)₃@PCN-608-SBDC was examined by aza-Henry reactions, which show good catalytic performance over three catalytic cycles.