| Metal-organic frameworks(MOFs)are organic-inorganic hybrid solids with infinite,uniform framework structures built from organic linkers and inorganic metal(or metal-containing cluster)nodes,these materials are usually widely used in the areas such as catalysis,fluorescence,magnetism,gas adsorption and separation due to its fascinating structural and diverse functions.This dissertation contained several different kinds of MOFs constructed from two basic ligand(1,4-tetrazinedi(4'-pyridyl)and 1,4-tetrazinedi(4'-pyrazolyl))with metal ions.As we known,the tetrazine group can efficiently react with some alkene compounds without catalyst,we called it Diels-Alder reaction.Under mild conditions,we introduced different substituents in the framework without changing the original framework and studied the impact of the substituents on the adsorption performance.In the first chapter,we briefly introduced the current research and progress of metal-organic framework based on pyrazole ligand;the progress of the dynamic and functional metal-organic frameworks(MOFs);the development of the functional post-synthetic modification(PSM)methods used in the area of MOFs.In the second chapter,under mild condition,[Cd(bipytz)2(SiF6)](1)was synthesized by using ligand 1,4-tetrazinedi(4'-pyridyl)(bipytz)and cadmium hexafluorosilicate,[Zn(bipydz)2(SiF6)](Compound 2)constructed by ligand 1,4-dizinedi(4'-pyridyl)(bipydz)and zinc hexafluorosilicate,bipydz was a product of D-A reaction.both compound 1 and compound 2,the metal centers is coordinated with four N atoms from the terminal pyridyl group to formed a 2D network in the ab plane,along the c axis,it was linked by two SiF62-,which formed a three dimensional structure.The crystal color of compound 1(contain tetrazine group)is red and it has a characteristic absorption peak in the visible region(about 550 nm),but the crystal color of compound 2(contain dizine group)is colorless,and it has no absorption peaks in the visible region(450-700 nm).In the third chapter,herein,we show that ligand 1,4-tetrazinedi(4'-pyrazolyl)(H2bptz)respectively reacts with a Cd(II)and Zn(II)salt to form two kinds of MOFs compound 3([Cd(bpdz)2(H2O)2]n)and compound 4([Zn(bptz)2]n)),The framework of compound 3 was rigid,it could be used as a selective separation material for carbon dioxide and nitrogen at 298 K and 1 bar condition with the selective ratio of 14.3:1.X-ray analysis of compound 4 revealed a tetragonal structure,featuring one-dimensional chains of Zn2+ ions,each tetrahedrally coordinated by N atoms from four independent bptz2-,pairs of Zn2+ ions along the chains are bridged by two pyrazolate rings.Post-synthetic modification of 4 to yield compound 5?6 and 7 was performed by D-A reaction between 4 and norbornadiene,isoprene and 1-hexene respectively without destroying the original structure while introducing different substituents on the framework.Compound 4-7 are found to be flexible porous networks,showing reversible dynamic response dependent on external stimuli.They contract drastically upon guest removal and expand again upon adsorption of DEF,N2 or CO2.Further experiment results show that the volume and the size of the substituents on the framework can affect the shrinkage and expansion of the framework.In the fourth chapter:briefly summarized the results and innovation of our research and at last,making a further prospect about MOFs in the application of the gas adsorption and storage. |
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