High-Entropy Lanthanide–Organic Framework as an Efficient Heterogeneous Catalyst for Cycloaddition of CO2 with Epoxides and Knoevenagel Condensation

Graphical A high-entropy lanthanide–organic framework (HE-LnMOF) heterogeneous catalyst toward sustainable CO 2 conversion reactions. The five rare earth metals were well-dispersed and randomly distributed in the structure. The HE-LnMOF possess multiple unsaturated metal centers, abundant Lewis acid and base interaction sites at the same time. The synergistic effect of multi-metallic Ln 3+ ions endow it with outstanding catalytic performance. Multimetallic synergistic effects have the potential to improve CO 2 cycloesterification and Knoevenagel reaction processes, outperforming monometallic MOFs. The results demonstrate superior performance in these processes. To investigate this, we created and characterized a selection of single-component Ln(III)-MOFs (Ln=Eu, Tb, Gd, Dy, Ho) and high-entropy lanthanide-organic framework (HE-LnMOF) using solvent-thermal conditions. The experiments revealed that HE-LnMOF exhibited heightened catalytic efficiency in CO 2 cycloesterification and Knoevenagel reactions compared to single-component Ln(III) MOFs. Moreover, the HE-LnMOF displayed significant stability, maintaining their structural integrity after five cycles while sustaining elevated conversion and selectivity rates. The feasible mechanisms of catalytic reactions were also discussed. HE-LnMOF possess multiple unsaturated metal centers, acting as Lewis acid sites, with oxygen atoms connecting the metal, and hydroxyl groups on the ligand serving as base sites. This study introduces a novel method for synthesizing HE-LnMOF and presents a fresh application of HE-LnMOF for converting CO 2 .