Design,Synthesis And Application Of Bimetallic Clusters And Sulfonate-based Metal-organic Frameworks

Metal-Organic Frameworks(MOFs)are a kind of porous crystalline material,which have a broad application prospect in molecular recognition,gas storage and separation,sensing and many other aspects.However,the current researches on MOFs are mostly based on single metal ions/clusters without charge,which greatly limits the development of MOFs.Both bimetallic and ionic MOFs have unique advantages in structure characteristics and overall properties due to the excellent synergistic effects between different metals and different charge species,so they have unique properties in catalysis,gas adsorption and separation.Therefore,compared to single metal MOFs,bimetallic MOFs have more properties possibilities.However,neither the structure nor the charges of the framework can be easily controlled in syntheses of MOFs,therefore it is a challenge to construct bimetallic ionic MOFs with both controllable structures and charges.Besides,in recent years,MOFs that,assembled by a single functional group and metal ions,have attracted extensive attention.However,relatively few reports have been made on the construction of MOFs materials by ligands with different functional groups.In this thesis,based on the Pearson's hard/soft acid/base(HSAB)principle,we proposed a method of designing bimetallic cationic MOFs.Firstly,we selected an organic ligand containing both azolate groups and carboxylate groups.Then the azolate groups as a soft base were coordinated with relative soft acid Cu²⁺,and the carboxylate groups as a hard base were bonded to the hard acid Zr⁴⁺(or Hf⁴⁺).After a series of experiments based on the one-pot method,two bimetallic cationic MOFs with a new topological structure,named PFC-24-Zr and PFC-24-Hf respectively,have been successfully obtained.Moreover,PFC-24-Zr can selectively adsorb anionic dye and efficiently remove Cr₂O₇^2-ions.In addition,another novel MOF material,named PFC-31,was synthesized by the reaction of an organic ligand containing pyridine and SO₃^-bifunctional groups with copper ions.According to the single-crystal X-ray analysis,PFC-31 shows one-dimensional chain structure with excellent thermal stability and chemical stability.Moreover,PFC-31 could efficiently catalyze the cycloaddition of CO₂ with epoxides in the presence of TBAB at 25°C and 1 bar of CO₂.Shortly,our study proved that PFC-31is one of a potential MOF catalyst that could realize the conversion of CO₂ under mild conditions,which could be contributed to the design and synthesis of such MOF catalysts.Finally,a summary and futher work plan base on our researches has been present at the end of this thesis.