| Metal-Organic Framework?MOF?is a new porous crystalline solid material formed by organic bridging ligands and inorganic metal ions or metal clusters through coordination bonds.Metal-organic framework materials have many advantages such as high porosity,large specific surface area,high crystallinity,controllable chemical structures and channel sizes.The diversity of coordination modes for organic ligands and the modification of functional groups on ligands make the abundant structures and functions of MOFs materials.These unique advantages for metal-organic framework materials own much attention.Thus MOF materials exhibit the important applications in many fields including gas adsorption and separation,proton conduction,fluorescence sensing,drug delivery and catalysis.In order to obtain good proton conducting MOF materials,a bifunctional ligand,5,7-disulfonate-1,4-naphthalenedicarboxylic acid,was synthesized.In the thesis,5,7-disulfonate-1,4-naphthalenedicarboxylic acid ligand was used to construct rare earth metal-based MOFs and transition metal MOFs.Their proton conductivities and luminescence properties were studied.The syntheses of the 5,7-disulfonate-1,4-naphthalenedicarboxylic acid ligand and its eight MOFs are presented in this thesis.The formulas for MOFs are listed as following:?1?{[La3??2-OH??DSNPDC?2?H2O?10]·4H2O}n?2?{[Nd3??2-OH??DSNPDC?2?H2O?9]·2H2O}n?3?{[Sm3??2-OH??DSNPDC?2?H2O?9]·2H2O}n?4?{[Eu3??2-OH??DSNPDC?2?H2O?9]·2H2O}n?5?{[Gd4?u3-OH?4?DSNPDC?2?H2O?11]·28H2O}n?6?{[Eu4?u3-OH?4?DSNPDC?2?H2O?11]·28H2O}n?7?[Cd2?DSNPDC??4,4?-bpy??H2O?2]n?8?[Cd2?DSNPDC??2,2?-bpy?2?H2O?4]n(DSNPDC4-:5,7-disulfonate-1,4-naphthalenedicarboxylic acid;4,4?-bpy:4,4?-bipyridine;2,2?-bpy:2,2?-bipyridine)This thesis is divided into the following five chapters:The first chapter mainly introduces the concept of metal-organic framework materials,synthesis methods,and properties of proton conduction,fluorescence,gas adsorption and separation,and heterogeneous catalysis.In the second chapter,the synthesis,infrared spectrum and solid-state fluorescence spectra of 5,7-disulfonate-1,4-naphthalene dicarboxylic acid organic ligand are presented.The naphthalene ring in the ligand is a conjugated?system with abundant?electrons and is a good fluorescent chromophore.The third chapter mainly introduces the synthesis,crystal structure,thermal stabilities,infrared spectra,powder X-ray diffraction patterns,proton conduction and fluorescence properties of rare earth metal-based compounds 1?6 constructed by5,7-disulfonate-1,4-naphthalenedicarboxylate ligand.Compounds 1?4 are isomorphic and three-dimensional structures with one-dimensional pore channels constructed by linear trinuclear Ln3 cluster secondary building units.The coordination modes of5,7-disulfonate-1,4-naphthalenedicarboxylate ligand are changed under different solvents,which lead to the other kind of rare earth metal-based compounds 5 and 6.In this paper,the proton conductivity and fluorescence properties of the representative compounds 4 and 6 were studied.In the three-dimensional structure of compound 4,the coordination water molecule and the free oxygen atoms sulfonate groups point to the one-dimensional pore surfaces.Lattice water molecules are filled in one-dimensional small channels.The lattice water molecules and the coordinated water molecules form hydrogen bonds with the sulfonate oxygen atoms and carboxylate oxygen atoms in the one-dimensional channels to give continuous well-defined hydrogen-bonding networks.The proton conductivity of compound 4 at 85? and 98%relative humidity is 1.040×10-4 S cm-1.The uncoordinated sulfonate groups in the two-dimensional layers of compound 6 point to the outer surfaces of the two-dimensional layer.Moreover,the square grids of the two-dimensional layers are filled with disordered guest water molecules.Under the same conditions,the proton conductivity of compound 6 is 2.283×10-55 S cm-1,which is lower than that of compound 4.At room temperature,compounds 4 and 6 show the characteristic emission peaks of Eu?III?.It was found that the Fe3+solution can absorb the energy of the excitation light,thus reducing the energy transfer from the organic ligand to the Eu?III?centers,which gives a quench effect of the luminescence for compound 4.The emission intensity is decreased with the increase of the concentration of Fe3+.Therefore,compound 4 can be used as a fluorescent probe for the detection of Fe3+.The two-dimensional layers of 6 packed into a close-packed three-dimensional structure to give no void for accommodation of the metal ions.So study of the similar sensing of metal ions for 6 is not performed.The syntheses,crystal structures,thermal stability,infrared spectra,powder X ray diffraction patterns,and fluorescence properties of Cd?II?compounds 7 and 8constructed by 5,7-disulfonate-1,4-naphthalenedicarboxylate and the N-containing ligands are provided in the fourth chapter.Compound 7 is a three-dimensional structurewhereintheCd?II?ionsarebridgedby5,7-disulfonate-1,4-naphthalenedicarboxylate and 4,4'-bipyridine ligands.In compound 8,two Cd?II?are bridged with carboxylate oxygen atoms to form a binuclear[Cd2??2-O?2?2,2?-bpy?2?H2O?]unit,which is linked by the carboxylate groups of 5,7-disulfonate-1,4-naphthalenedicarboxylate ligands to give a one-dimensional chain.The hydrogen bonds and?···?stacking interactions between the one-dimensional chains link the chains to form three-dimensional supramolecular structure.The solid-state emission peaks of compounds 7 and 8 are 378 nm and 376nm respectively,which are blue-shifted with the emission peak of5,7-disulfonate-1,4-naphthalenedicarboxylic acid ligand.The emissions for 7 and 8can be attributed to the transitions of oxygen to 5s orbits of Cd?II??ligand-to-metal transition?.The two compounds display very low proton conductivities even under high humidity due to the presence of the highly hydrophobic N-containing ligands.The fifth chapter summarizes the work of this paper,and puts forward some suggestions for improvement of the work. |
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