Design,Synthesis And Catalytic Activity Of Cyclic Trinuclear Metal Clusters Based Porous Materials Via Linkage Of Dynamic Covalent Bond

Metal-organic frameworks(MOFs)are composed of organic ligands bonded to metal ions by strong forces.Abundant metal nodes and organic connectors can make the composition and structure of MOFs easily adjustable,and the MOFs have enriched the research scope of inorganic chemistry to a large extent.Recently,covalent organic frameworks(COFs)via a linkage of covalent bond between organic linkers with periodic structure has become a emerge reaseach filed.With the successful synthesis of MOFs and COFs,an important step has been taken to develop strong covalent bonds and metal coordination bonds besides molecules.As a new class of porous materials,MOFs and COFs have adjustable pores,good crystallinity,periodicity and structural diversity,allowing the potential applications in gas adsorption and separation,catalysis,chemical sensing and energy storage,etc.The metal clusters,composed of metal and ligands,originated in the 1980s.It contains several or even thousands of atoms,molecules or ions,which can form relatively stable microscopic or submicroscopic aggregates through physical or chemical interactions.Metal clusters have been widely used in biological imaging,drug carriers,catalysis and biological detection and possess different structures,functions and applications.Therefore,combining metal clusters and chemistry of MOFs has great advantages.Although metal clusters-based MOF materials have been successfully synthesized and applied,reticular materials combining metal clusters and COFs have not been explored.Cyclic Trinuclear Complexes(CTCs)have been widely studied due to their metallophilicity and highly tunable?-acidity/basicity.In this paper,a series of new covalent metal-organic frameworks(CMOFs)have been successfully synthesized by amine-aldehyde condensation reaction of cyclic trinuclear complexes and organic ligands.The structure was determined by powder X-ray diffraction and its catalytic performance was also carefully studied.In the first part,two Cu(I)CTCs-based CMOFs(JNM-1 and JNM-2)were successfully prepared either by stepwise or one-pot methods.JNM-1 and JNM-2exhibit good water,solvent and thermal stability,and achieve reversible redox of the Cu valence state in the framework without destroying crystallinity.Based on their excellent stability,JNM-1 can be used as a catalyst for Sonogashira coupling reaction,in which JNM-1 has high catalytic efficiency and the applicability of the reaction substrate,and does not lose catalytic activity during the five catalytic cycles.In addition,JNM-1 can also be used as a catalyst for the synthesis of conjugated molecular wires.In the second part,JNM-3 was prepared using C₃-symmetric Cu(I)CTCs and C₂-symmetric anthracene-2,6-diamine.Interestingly,the stacking mode of the framework can be regulated by changing the acidity of catalyst.For instance,the ABC stacking structure(JNM-3-ABC)as yellow powders was obtained when 6 M acetic acid was used;while the AA stacking structure(JNM-3-AA)as red powders was obtained when6 M trifluoroacetic acid was ultilized.Variations of interlayer stacking greatly affect their functions,including porosity,chemical stability and catalytic activity.In addition,adding a small amount of trifluoroacetic acid to the suspension of JNM-3-ABC can convert JNM-3-ABC to JNM-3-AA,further confirmed by PXRD analysis,dynamic dye adsorption removal experiments and BET tests.