Synthesis And Properties Of MOFs Constructed By 4,5-bis(teilrazol-5-yl)imidazole Ligand

Metal-organic frameworks?MOFs?,as a class of fast-developing materials,have attracted much attention from researchers in these years due to their unique crystal structures.MOFs have already been verified to show potential applications in gas adsorption,gas/liquid separation,sensor,catalysis and photo-electronics.The diverse applications of MOFs originate from the unique structures built by coordinating metal ions?metal clusters?with organic molecules.The structures diverse from 1 dimension to 3 dimensions.A big barrier for MOFs in practical applications is the low stability,which arises from the lower bond energy of coordination bonds.Most MOFs can be destroyed easily in acid solution,high temperature,water,or even in the air.On the basis of massive works,researchers have found that azolates have the ability to form strong coordination bonds with metal ions.Thus,we have chosen a new polytetrazolate ligand of 4,5-bis?tetrazol-5-yl?imidazole and zinc ion to construct a series of new MOFs:1.The first MOF is Zn₃?IBT?₂?H₂O?₂?represented as compound 1?.Compound 1 is characterized by single crystal X-ray diffraction and shows a three dimensional framework.Compound 1 shows superior chemical stabilities in terms of water resistance?>3 months in water,>1 week in boiled water?,acid/base tolerance?pH from 2.0 to 12?and solvent anticorrosion?e.g.N,N-dimethylformamide,methanol,etc.?.In addition,this MOF shows moderate proton conductive property with a conductivity of 1.98×10^-5 S cm^-1 at 30?and 97%RH.2.Compounds 2 to 4 are[Zn₃(C₅HN₁₀)₂?H₂O?₂]·?H₂O?,[Zn₂(C₅H₂N₁₀)?H₂O?]·(C₁₀H₈N₂)and Zn₄(C₅HN₁₀)₃?H₂O?₃.They are characterized by single crystal X-ray diffraction,powder X-ray diffraction and thermogravimetric analysis.Compound 2 shows good stability?140?in air and 3 days in water?.Compound 3 is stable above 250?in air and one month in water.And compound 4 is stable in water for at least 3 days.Compound 2 is characterized by adsorptions of CO₂,N₂,ethanol and water.It exhibits the ability to separate CO₂/N₂ as well as ethanol/water.The result shows us that azolate 4,5-bis?tetrazol-5-yl?imidazole can form relatively stable MOFs.This thesis provides more information on the designed synthesis of applicable MOFs.