Rational Design,assembly And Co₂ Fixation Reaction Properties Of Zr-MOF,Fe-MOF Based On Biphenyl Platforms

As a new type of porous materials,metal-organic frameworks?MOFs?have attracted considerable attention and widely used in gas storage and separation,heterogeneous catalysis,electroconduction and magnetism,because of the typical porosity,high thermal and chemical stability,easy to recycle and reuse.In this contribution a kind of polycarboxylate ligand based on axially C₂-symmetric Biphenyl Platforms was synthesized and successfully got two kinds of porous MOFs after self-assembly with Zr⁴⁺and Fe³⁺.Their structure and stability were studied through a series of characterization methods,such as single crystal X-ray diffraction,infra-red spectrum,Powder X-ray diffraction,thermogravimetric analysis.At last,the catalytic activity of the catalyst in the cycloaddition of CO₂ to the epoxides was studied.This paper is divided into the following three chapters.In chapter 1,this paper introduced the development history of MOFs,mainly including the synthesis of MOFs and their applications in the area of gas storage and separation,heterogeneous catalysis,chemical sensing and luminescence.Than,the issues and challenges in the study of MOFs are briefly described,and summarized the significance and progress of this thesis.In Chapter 2,an axially C₂-symmetric ligand,named H₄L was prepared.After self-assembled with Zr⁴⁺and Fe³⁺,two kind of crystalline MOFs,named Zr-MOF and Fe-MOFweresuccessfullysynthesized.The crystal structures were well characterized by single crystal X-ray diffraction.PXRD,TGA and CO₂ adsorption isotherm sured that such two MOFs which built up from high valence cations have high thermodynamic stability and chemical stability.catalytic performance of Zr-MOF and Fe-MOF in the cycloaddition of CO₂ with epoxides to produce various carbonates was explored.Under 1.0 MPa of CO₂ at room temperature for 36 h,the yield reached 85%and 78%respectively for propylene oxide.After substrate development,we found Zr-MOF and Fe-MOF have catalytic activity to a series of epoxides compounds.After five cycles,the yield was basically unchanged,this also fully shows the stability of the two kinds of MOFs materials.In Chapter3,the summary and prospect of the work of this paper are given.