Adsorption Properties Of Metal-Organic Frameworks Assembled By Nitrogenous Carboxylate And Pentacarboxylate Ligands

Up to now,Metal-Organic Frameworks(MOFs)constructed by inorganic metal ions or metal clusters coordinated with organic ligands have made significant progress.MOFs materials,as a kind of crystalline porous material,have the advantages of high porosity,diverse topologies,adjustable pore sizes,and high chemical stability,making them useful in gas adsorption,the removal of organic and inorganic pollutant,fluorescence sensing,heterogeneous catalysis,electrochemistry,solar batteries and so on.MOFs materials with unique properties are synthesized by functionalized organic ligands to enhancing their application:fluorescent organic ligands can give MOFs materials interesting luminescent properties,making them have potential applications in fluorescence detection and photocatalysis;nitrogenous carboxylic ligands can prepare MOFs with various topological structures through the coordination of N/O atoms with metal ions,and the uncoordinated nitrogen atoms can improve the gas adsorption performance of the materials.In addition,polycarboxylic acid ligands can be used to construct MOFs with novel topological structures due to their flexible coordination patterns.In this paper,we designed and synthesized three nitrogen-containing tetradentate carboxylic acids ligands to prepare three Zr-MOFs materials through the modulator synthesis method.These materials have been explored for gas adsorption and separation,the removal of pollutants,photocatalysis and fluorescence detection.In addition,by using pyrazine tetradentate carboxylic acid ligand,pyrazine bidentate carboxylic acid ligand and pentadentate carboxylic acid ligand concatenated with In³⁺,Al³⁺and Cu²⁺metal ions,respectively,we also successfully constructed 6compounds and investigated their gas adsorption and Separation,dye adsorption and separation,fluorescence detection and other properties.The research results of this paper are mainly divided into the following three parts:1.The syntheses of Zr-MOFs constructed by nitrogenous tetradentate carboxylic acid ligands.In this section,we designed and synthesized three nitrogenous tetradentate carboxylic acid ligands with AIE effect:2,3,5,6-tetracarboxyphenyl pyrazine(H4TCPP),the extended H4PTTBPC and H4PPTTC organic ligand containing pyrrolo[3,2-b]pyrrole core.Three fluorescent Zr-MOFs with ultra-high stability(compounds 1-3)were constructed by these three organic ligands coordinated with Zr Cl4,respectively,through the modulator synthesis method.Due to the ultra-high stability and fluorescence performance,compound 1-3has outstanding performance in fluorescence detection,photocatalysis and pollutant adsorption.As a multifunctional material,compound 1 can quickly adsorb,efficiently detect and photodegrade Cr2O7^2-ions in water,thus achieving the wastewater purification.Compound 2 is a 2-fold interpenetrated Zr-MOF material with scu topology.Compound 2 modified by Co²⁺and Ni²⁺exhibits excellent CO₂photoreduction performance,improving the photocatalytic activity.Because of its open straight channels and the exposed-OH groups,Compound 3 is able to efficiently adsorb bisphenol A in water.2.The adsorption properties of In-MOFs and Al-MOF materials constructed with H₄TCPP ligands.In this section,H4TCPP ligands concatenated with In³⁺and Al³⁺metal ions to construct three p-group MOFs materials(compounds4-6)under solvothermal conditions,and we explored the relationship between the structure and performance.Compounds 4 and 5 are both(4,4)-c anion skeleton structures with mononuclear indium secondary building units(SBUs).On account of the different dihedral angles formed by the distortion configuration of the ligand,compound 4 and 5 have different topologies:compound 4 has a novel topological structure;compound 5 is qtz topology.These two In-MOFs materials can adsorb cationic organics according to the Coulomb force interaction:Compound 4 has large irregular cages and one-dimensional straight channels,which can efficiently adsorb large doxorubicin hydrochloride(DOX)molecules;Compound 5 with three open straight channels can efficiently and selectively adsorb and separate carcinogenic dyes BR9 and BV14.In addition,compound 6 is a three-dimensional skeleton structure constructed by Al-O-Al metal chain,which exhibits excellent chemical stability and good adsorption capacity for water vapor.3.The syntheses of MOFs constructed from H₅DDCBA and H₂PDDA ligands.In this section,we successfully prepared a chiral In-MOF(compound 7)and a copper indium doped bimetallic MOF(compound 8)by the connection of pentadentate carboxylic acid and In³⁺and Cu²⁺metal ions under the solvothermal synthesis conditions.Compound 7 is a chiral compound with an infinite chain containing repeated pentameric indium SBUs.Among them,compound 7P can selectively recognize chiral organic amines through fluorescence quenching.Cu-indium doped compound 8 not only has multi-level channels,but also has open Cu/In metal sites,showing the good adsorption performance of CO2.Finally,compound 9 was synthesized by the reaction of pyrazine bidentate carboxylic acid ligand with Cu²⁺metal ion.In the structure,the carboxylic acid groups of the ligand connect paddle-wheel-like[Cu2(COO)4]clusters to form the Kagome two-dimensional layers,and the terminal groups of[Cu2(COO)4]clusters in Kagome layers chelate the N atoms of the ligand to constitute the three-dimensional skeleton structure.The material not only has exposed N sites and open Cu metal sites,but also has three kinds of large pores with window sizes of 13.4×15.6,17.9×8.7 and12.7×12.7A²,respectively.In summary,we utilized nitrogenous carboxylate and pentacarboxylate ligands to coordinate with metal ions Zr⁴⁺,In³⁺,Al³⁺and Cu²⁺to construct 9 compounds,and investigated their performance of fluorescence sensing,photocatalysis,adsorption and separation of organic and inorganic pollutants and gas adsorption and separation.