Novel 3D Metal Organic Frameworks:Synthesis,Structure And Properties

Metal-organic frameworks(MOFs)are a new category of advanced porous materials undergoing study by many researchers for their vast variety of both novel structures and potentially useful properties arising from them,such as their high porosities,tunable structures,large specific surface area,etc.In this work,we successfully synthesized five novel MOFs with high thermal and chemical stability,and then,through a series of measurements like X-ray single crystal diffraction,Powder X-ray diffraction(PXRD)measurements,infrared,elemental analysis,thermogravimetry,fluorescence analyzer,ultraviolet,and atmospheric pressure adsorption,based on their properties,we mainly explored their unique characteristics in three aspects:fluorescence tuning,radioactive iodine capture,and gas selective adsorption and separation.main research contents and results were as follows:1.Three novel Pb-MOFs were successfully synthesized by the rigid pyridine-carboxylic acid ligand 5-(pyridin-4-yl)isophthalic acid(H2pia)and Pb2+with the regulation on organic and alkali templates:[Pb2(pia)2(DMA)]·DMA(1),[Pb2(pia)2(DMF)]·1.5DMF(2)and[Pb2(pia)2(DMF)]·NEt3(3),Compounds 1-3 were analysized by single-crystal diffraction,we found that they had isorecticular rod-spacer structures with 1D square channels surrounded by double-linker walls but possessed subtle difference in Pb(II)coordination geometry,apical ligand,solvent template,and framework distortion.However,fluorescence has changed dramatically due to subtle structural differences.This chapter mainly studied the basic fluorescence properties and fluorescence tuning properties of three Pb-MOFs.In summary,even slight structural modulations on the Pb coordination geometry and Pb…Pb interactions could have significant effects on the solid-state properties,generating continuous broadband white emission in 1,a single yellow emission in 2,and dual-peak white emission in 3.2.Based on the synthetic materials in the previous chapter,this chapter mainly adds more triethylamine solvent to the synthesis of the above compound 3,which causes its structure to be transformed from a stable column chain structure to a highly stable cluster-based structure.[Pb6(?6-O)2(Pia)4]·4DMF,because this framework contains more lead elements and has higher chemical and thermal stability,this chapter mainly studies its details from water The nature of capturing radioactive iodine,the experimental results show that the compound can not only capture iodine from aqueous iodine solution quickly,but also from iodine water with a concentration as low as 0.00001 mol/L.3.In this section we use a triangular rigid carboxylic acid ligand[1,1'-biphenyl]-3,4 ',5-tricarboxylic acid(H3bpt)and Ni2+to construct a 3-12 connection topology with high porosity and stability.The metal-organic framework mainly explores the chemical and thermal stability of the framework,and explores its adsorption performance for N2,CO2,and CH4 through a series of adsorption tests.Experimental results show that the compound is an excellent thermal stability and chemically stable materials,and show separation performance for CO2/N2 and CO2/CH4.