Design, Synthesis And Properties Of Luminescent Lanthanide Metal-Organic Frameworks

In the past two decades, metal-organic frameworks (MOFs) emerged as as a new class of multifunctional materials. The coexistence of intrinsic porosity.high surface area.Easy functionalization. flexible tailor and decoration enables their applications in a variety of fields such as Iuminescence.magnetism. gas storage and separation, catalysis, sensor, chiral separation and so on. They have attracted more and more attention of not only the academic field but also the industrial field. Carboxylic acid ligands can coordinate in various ways and their coordination ability are quite strong. In recent years metal organic framework material by constructed by Carboxylic acid ligands has gradually become a hot topic in the field of coordination chemistry. The lanthanides have a not completely filled4f electron shell and various lanthanoid the4f electron numbers are different.So Every lanthanoid has their own special properties, especially optical and magnetic properties. Over the last decade, the lanthanides were selected as metal centers of the metal-organic frameworks by more and more chemical workers. In this thesis, p-phenylenediacrylic acid and homemade9.9-dimethyl-fluorene-2.7-dicarboxylic acid are used as bridging ligand and lanthanoid were used as metal centers. With self assemble theory.we synthesized twelve new metal-organic frameworks. These complexes (1-12) were characterized by single crystal X-ray diffraction.powder X-ray diffraction, elemental analysis.thermogravimetric analysis and IR spectrum. The fluorescent properties of the complexes were studied. The main contents of this thesis are summarized as follows:1. Based on p-phenylenediacrylic acid and lanthanoid, we synthesized three new metal-organic frameworks under solvothermal condition,[Ln2(pda)2(HCOO)(OH)(H2O)]n (Ln=Dy,1;Tb,2;Ho,3; H2pda=p-phenylenediacrylic acid). We found that they are isostructural by structural characterization. They all possess a3D architecture with the pcu net topology based on the parallel1D lanthanide-oxygen rod-shaped secondary building units. The photoluminescent properties of1-3have been investigated at room temperature. Complexes1-3all display the intense blue emission in the solid state. Especially. compared with the free H2pda ligands. complex1shows the strong fluorescence enhancement due to the complexation.2. Under solvothermal conditions. we use9.9-dimethyl-fluorene-2,7-dicarboxylic acid, lanthanoid and synthesiz five new metal-organic frameworks.[Ln3(MFDA)4(NO3)(DMF)3]n(Ln=Eu,4;Sm,5:Dy,6; Tb,7:Gd,8; H2MFDA=9,9-dimethyl-fluorene-2,7-dicarboxylic acid). They were structurally characterized by single-crystal X-ray diffraction. They are-isostructural. They are three-dimensional coordination polymer with pcu type rod-packing structure, through which1D rhombic channels penetrate. We studied their thermal stability and luminescence properties. Especially the potential of Complex4for nitro explosive and Fe3+ion sensing is studied through luminescence quenching experiments, which show that Complex4is a potential luminescent sensory material for both nitro explosives and Fe3+ion.3. Also we use9,9-dimethyl-fluorene-2,7-dicarboxylic acid and lanthanoid. under different solvothermal conditions with the above.we afforded four new metal-organic frameworks,{[Ln2(MFDA)2(HCOO)2(H2O)6]·H2O}n (Ln=Eu,9;Dy,10:Tb,11:Gd,12; H2MFDA=9,9-dimethyl-fluorene-2.7-dicarboxylic acid). Structural characterization shows that they are isostructural. They possesses the three-dimensional pcu type rod-packing structure with one-dimensional rhombic channels. The framework of them can reversibly shrink/swell along the c axis upon partially/fully release of the water molecules. We also studied the thermal stability and luminescence properties of complexs10-12. The potential of Complex9for Fe3+and PA sensing was studied in DMF through the luminescence quenching experiments, which shows Complex9is a potential turn-off luminescent sensory material for the selective detection of Fe3+ion and PA.