Highly Efficient Catalysts for CO 2 Fixation using Guanidinium‐Functionalized Zr‐MOFs

An effective approach for tuning CO 2 adsorption, activation and transformations of various epoxides in CO 2 fixation reactions is introducing functional groups into the pores of metal‐organic frameworks (MOFs) through ligand modification. Herein, a novel ionic ligand, 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene‐biphenyl‐4,4′‐dicarboxylic acid (H 2 BPDC−[TBD] + Br − ), was synthesized to construct derivatives of the cationic guanidinium‐containing Zr‐MOF (UiO67‐[TBD] + Br − ) with free bromide ions, as multifunctional heterogeneous catalysts. The materials were characterized comprehensively by multiple techniques such as PXRD, FTIR, TGA, SEM, EDS, 1 H NMR, 13 C NMR, mass spectrometry (MS), elemental analysis, as well as N 2 and CO 2 adsorption measurements. The synthesized UiO67‐[TBD] + Br − exhibits an efficient heterogeneous catalytic performance in the CO 2 fixation reaction with epoxides, with high yield and selectivity, under mild conditions (0.1 MPa CO 2 , 80 °C, without co‐catalyst and solvent). In addition, these catalysts display good thermal stability, recyclability and could be reused at least five times without a significant decrease in their catalytic performance.