Studies On The Synthesis,Structure And Performance Of MOFs Constructed By Azadicarboxylic Acid Ligands

Metal-organic frameworks(MOFs)have the characteristics of high specific surface area,flexible functions and structures,so they are used in gas storage,gas adsorption and separation,chemical sensing,optics and other fields.It is a porous material composed of metal ions or clusters and organic ligands.It has attracted the attention of lots of researchers due to its potential application value in many fields.In this paper,under solvothermal synthesis conditions,by choosing H2DTTA=1,4-bis(triazol-1-y1)therephthalic acid and H2ATDBC=4,4'-(4-amino-4H-1,2,4-triazole)-3,5-diyl dibenzoic acid as organic ligands,and then adjusting the ratio of the reactants,the polarity of the solvent,the reaction temperature and the reaction time and other conditions.Six MOFs with novel structures have been successfully synthesized.And detailed structural analysis and a series of property tests were carried out,including gas adsorption and separation property,iodine adsorption property and fluorescence property.This paper includes the following research work:(1)Study on the synthesis,structure and performance of CuDTTA and CuIATDBC:Two MOFs(CuDTTA and CuIATDBC)with novel structures were successfully synthesized using H2DTTA and H2ATDBC as organic ligands and CuCl2 and CuI as metal sources.For CuDTTA,each Cu2+ion is coordinated by two oxygen atoms and two nitrogen atoms from four ligands.Each ligand is connected to four Cu2+ions through its two carboxylate groups and two nitrogen atoms.They can be considered as typical quadrilateral polyhedron.It can be simplified 4-connected network composed of Cu2+ions and ligands and is a lvt topological structure with permanent porosity.Therefore,its adsorption and separation performance for CO2,CH4,C2H2,C2H4 and C2H6 were tested.The experimental results showed that the CuDTTA has good selectivities for C2H2/CH4 and CO2/CH4.In the structure of CuIATDBC,it is characterized by paddle-shaped binuclear copper and binuclear Cu2I4 cluster.Overall,the CuI and the ligand are connected to expand into a three-dimensional network,which can enhance the stability of the structure and facilitate the adsorption and freed of iodine.(2)Study on the synthesis,structure and performance of CdDTTA and MnDTTA:Two MOFs(CdDTTA and MnDTTA)with novel structures were successfully synthesized using H2DTTA as organic ligands and CdCl2 and MnCl2 as metal sources.The single crystal structure analysis shows that the two compounds are isostructural.By adapting to the surrounding environment,the structure can be stretched or expanded.They exhibit unusual gradual and delayed gas adsorption behavior,which show special structural flexibility in the adsorption and desorption of specific gas.Interestingly,they display flexible structure with the uncoordinated N,O atoms in the framework.And this "breathing effect" makes C2H2 adsorption of CdDTTA rise quickly at a certain opening pressure and enhances the C2H2 adsorption and storage effect.In addition,these two MOF materials both show good iron ion detection property and can be used as materials with potential development in fluorescence detection.(3)Study on the synthesis,structure and performance of EuDTTA and TbDTTA:Two MOFs(EuDTTA and TbDTTA)with novel structures were successfully synthesized using H2DTTA as organic ligands and Eu(NO)3 and Tb(NO)3 as metal sources.Single crystal structure analysis shows that the compounds are isostructural.They exhibit two-dimensional network structure,which are stable in water,and have a good detection effect on iron ions in water and can be used as potential fluorescent materials for iron ion detection.