Syntheses,Structures And Properties Of Coordination Polymers Based On N-containing Heterocyclic Dicarboxylate Ligands

In recent years,coordination polymers?CPs?,which are also called metal organic frameworks?MOFs?,as one of the most important research fields in chemistry and materials science,show a very rapid development trend and are becoming an important component of porous materials.CPs not only have rich and interesting network topologies,but also have many potential applications,such as gas adsorption and separation,catalysis,luminescence,sensing,proton conduction and so on.Their crystalline properties,permanent high porosity,uniformly distributed pore size,excellent surface area,controllable pore surface properties,and potential industrial scale expansibility allow these materials to have the potential for further investigation.Among CPs,rare earth based CPs have received extensive attention.Since the rare earth ions usually adopt varide coordination modes?octa or dodec?and have special luminescent properties,the coordination polymers constructed by rare earth ions exhibit various structures.In addition,the incorporation of heteroatoms such as N atoms in the organic ligands,can greatly increases the possibility of the formation of coordination polymers with novel frameworks.In this work,six coordination polymers were synthesized under hydrothermal and solvothermal conditions,using N-containing dicarboxylic acid ligands as organic ligands and rare earth metals?such as scandium,europium,terbium,gadolinium and erbium?as metal centers.The luminescence,catalysis and adsorption properties of these six coordination polymers were further studied.The main contents are as follows:1?Respectively,using 2,5-pyridinedicarboxylic acid,2,3-pyrazine dicarboxylic acid as an organic ligand and scandium as the metal center,two coordination polymers [Sc₂L₂¹?HL¹?₂?H₂O?₂]·H₂O?H₂L¹=2,5-pyridinedicarboxylic acid??1?and ScL²?HL²??DMF??H₂L²=2,3-pyrazinedicarboxylic acid??2?have been successfully synthesized.Compound 1 exhibits a 2D layered structure,and compound 2 is a 1D chain structure.Moreover,compound 1 exhibits good fluorescence property and dye adsorption property,as well as good catalytic performance.Compound 2 shows good catalytic performance and fluorescence property.2?Four coordination polymers,Na[Eu?C₂O₄?₂?H₂O?]·2H₂O?3?,Na[Tb?C₂O₄?₂?H₂O?]·2H₂O?4?,Na[Gd?C₂O₄?₂?H₂O?]·2H₂O?5?and Er₄L₄¹?DMF??OH?₄?H₂O??H₂L¹=2,5-pyridinedicarboxylic acid??6?,were synthesized by using 2,5-pyrazinedicarboxylic acid and 2,5-pyridinedicarboxylic acid as organic ligands,using rare earth ions europium,terbium,gadolinium and erbium as metal sources.Compounds 3-5 are isomeric and exhibit 2D layered structure.It is noted that the organic solvents in situ decompose during the synthesis process.Compound 6 is a 3D structure containing the tetranuclear clusters.compounds 3-5 were characterized by fluorescence spectroscopy,and the characteristic peaks of the corresponding metal ions were found.In addition,the dye adsorption experiment was carried out on compound 3,and the dye adsorption was observed.For compound 6,we performed the near-infrared region fluorescence test,which showed the characteristic peak of erbium???and compound 6 also had good dye adsorption performance.