Synthesis,Structure And Fluorescence Properties Of Lanthanide Coordination Polymers Based On Two Aromatic Polycarboxylic Acid Ligands

Two aromatic polycarboxylic acid ligands and lanthanides were used to synthesize two series of sixteen lanthanide coordination polymers by hydrothermal synthesis.They were characterized by elemental analysis,infrared spectroscopy,powder X-ray diffraction,thermo-gravimetric analysis,and photoluminescence properties.1.Selected flexible aromatic tricarboxylic acid ligand 2-（3,5-dicarboxybenzyloxy）ben-zoic acid（H₃dcob）with lanthanide,water and N,N-dimethylformamide（DMF）as solvent.Hydrothermal synthesis of a series of isomorphic new three-dimensional lanthanide coordina-tion polymers[Ln（dcob）（DMF）（H₂O）]_n[Ln=Pr（1）,Nd（2）,Sm（3）,Eu（4）,Gd（5）,Tb（6）,Dy（7）,Er（8）].X-ray single crystal diffraction results indicate that eight compounds 1-8 are isomorphous crystals in the monoclinic space group C2/c.Topological analysis shows that compounds 1-8 can be simplified to a two-node 3,6-connected flu-type topology with the Schl?fli symbol{4².6}₂{4⁴.6².8⁷.10²}.Compounds 3,4,6,7 have typical lanthanide ion lum-inescence.The fluorescence decay curve of Compound 4 was tested.The luminescence decay curve can be fitted by a double exponential function.The lifetime components areτ₁=3.84μs（4%）andτ₂=578.5μs（96%）.The quantum efficiency is 23.29%.The low tempera-ture phosphorescence spectrum of Compound 5 was tested.2.Selected flexible aromatic dicarboxylic acid ligand 2-（4-carboxybenzyloxy）benzoic acid（H₂cob）and lanthanide,water and N,N-dimethylformamide（DMF）as solvent,hydro-thermal synthesis Series of isomorphic one-dimensional chain structures of lanthanide coord-ination polymers[Ln（cob）（DMF）]_n[Ln=La（9）,Ce（10）,Pr（11）,Nd（12）,Sm（13）,Eu（14）,Gd（15）,Tb（16）].X-ray single crystal diffraction results show that the coordination polymer9-16 belongs to the crystallographic isomorphic triclinic P-1 space group,and the fluores-cence properties of the coordination polymers 13,14,16 are studied.