Design,Syntheses And Structural Characterization Of Ln(?)-Ag(?)metal-organic Frameworks

Metal-organic coordination polymers have attracted extensive attention and exploration due to their enormous variety of structures and their applications in various areas such as magnetism,luminescence,gas adsorption,sensors,separation,and so on.In recent years,chemists have devoted themselves to this field as a result of the introduction of the multidentate ligands with N-O atoms including N-heterocyclic dicarboxylate ligands.Compared with the synthesis of homometallic coordination compounds containing lanthanide?Ln?or transition?TM?metals,constructing lanthanide-transition?Ln-TM?heterometallic coordination compounds is very difficult because of the competing reaction between transition metals?TM?and lanthanides during the reaction progress.Thus,it is a great challenge to synthesize Ln-TM heterometallic coordinaton compounds.In this paper,2-?pyridin-4-yl?-1H-imidazole-4,5-dicarboxylic acid?H₃PIDC?and benzimidazole-5,6-dicarboxylic acid?H₃BIDC?are adopted as the organic ligands and transition metal Ag?I?,lanthanide metals Ln?III?as the matal centers and six metal coordination polymers are obtained by hydrothermal method through adjusting metal-to-ligand ratios,pH value,time and temperture of reaction.All of these compounds were characterized by elemental analysis,infrared spectroscopy?IR?,and powder X-ray diffraction and further determined by single-crystal X-ray diffraction analysis.The thermal stabilities and luminescent properties of selected compounds were investigated.Main work is summarized as follows:1.One transition metal coordination compound {[Ag1.5?HPIDC?]}n?1,H₃PIDC=2-?pyridin-4-yl?-1H-imidazole-4,5-dicarboxylic acid?was synthesized by selecting the H₃ PIDC as organic ligand and Ag?I?as the center metal under hydrothermal condition.2.Two lanthanide metal coordination compounds were synthesized under hydrothermal condition.In compound 2 [Er?HPIDC??ox?0.5H₂O]·2H₂O?H₃PIDC=2-?pyridin-4-yl?-1H-imidazole-4,5-dicarboxylic acid,ox=oxalic acid?,the H₃ PIDC is used as the main ligand,oxalic acid as the co-ligand and Er?III?as the centre atom.While in compound 3 [La?HBIDC??ox?0.5?H₂O?]·H₂O?H₃BIDC=benzimidazole-5,6-dicarboxylic acid,ox=oxalic acid?,the H₃ BIDC is selected as the main ligand,oxalic acid as the co-ligand and La?III?as the centre atom.In both of them the oxalate ion is used as co-ligand but the synthesizing strategies are different due to the different main ligands introduced.This work can provide a reference for the synthesis of coordination polymers containing similar organic ligands.3.Three Ln-Ag heterometallic coordination compounds [Ln2Ag6?PIDC?4]?Ln=Er 4,Gd 5,Eu 6,H₃PIDC=2-?pyridin-4-yl?-1H-imidazole-4,5-dicarboxylic acid?were synthesized under hydrothermal conditions by selecting the H₃ PIDC as organic ligand,and their structures,infrared spectroscopy?IR?,powder X-ray diffraction and thermal stabilities were investigated.