Synthesis And Catalytic Performance Of Functionalized MOFs Materials On Carbon Dioxide Cycloaddition Reaction

Reducing greenhouse gas carbon dioxide（CO₂）is an important topic in the current research of modern chemical world.How to make better use of carbon resources and convert carbon dioxide as renewable C1 resource into valuable chemicals has been paid more and more attention.Among them,the conversion of CO₂ and epoxide into cyclic carbonate has attracted widespread attention because of its high resource utilization and wide application range,which conforms to the concept of"sustainable development"and"green chemistry".In recent years,MOFs has been developed as heterogeneous catalyst for CO₂ cycloaddition because of its abundant Lewis acid-base active sites,good stability and excellent CO₂ adsorption performance.Therefore,the paper designs and synthesized MOFs materials with different functions to realize the efficient conversion of carbon dioxide and epoxy compounds.The main contents of this paper are as follows:（1）we reported a facile strategy for the preparation of tri-functional ionic MOFs incorporating imidazolium cation functionalities.This strategy exploits Debus-Radziszewski reaction to create the cationic imidazole ring via a post-synthesis modification（PSM）method,and meanwhile to introduce exchangeable counteranions.Based on this strategy,MIL-101-IMOH-Br^-have been prepared for the first time which combines Lewis acidic sites,Br?nsted acid sites and nucleophilic centers to achieve the purpose of catalyzing for the CO₂-epoxide cycloaddition into cyclocarbonate under solvent-free and co-catalyst free conditions.Moreover,MIL-101-IMOH-Br^-still showed brilliant activity and stability after recovering and recycling five times.（2）Four hexanuclear metal cluster MOFs,NH₂-UiO-68（Y）、NH₂-UiO-68（Yb）、NH₂-UiO-68（Zr）、NH₂-UiO-68（Hf）,were synthesized by solvothermal reaction using a functionalized linear ligand,2′-amino-1,1′:4′,1′-terphenyl-4,4′-dicarboxylic acid（H₂TPDC-NH₂）.They were used to catalyze the cycloaddition of carbon dioxide and epoxy compounds at room temperature and atmospheric pressure.Because of the high density of Lewis acid sites and Br?nsted basic sites,these complexes have excellent catalytic activity.