Study Of Syntheses,Structures And Properties As Fluorescence Sensors Of Luminescent Coordination Polymers Based On Imidazole-Containing Polycarboxylic Acid Ligands

In this dissertation,1H-imidazole-4,5-dicarboxylic acid（H₃imdc）and2-（pyridin-2-yl）-1H-benzoimidazole-5-carboxylic acid（Hpbca）are used as the main ligands.Seven coordination polymers were synthesized by self-assembly design under hydrothermal/solvothermal conditions by adjusting the metal salt ratio,temperature,time,etc.The structure and properties of the seven compounds were analyzed and characterized through IR,Elemental Analysis,X-ray single crystal diffraction,X-ray powder diffraction,Thermogravimetric,UV-vis spectrum,fluorescence spectrum,etc.Focused on the fluorescence sensing properties of these coordination polymers as some inorganic ions,nitro explosive molecules and amino acid molecules;and the possible fluorescence responsive mechanisms were studied in detail.The main research contents of this paper are as follows:1.Five isomorphic rare earth-transition heterometallic coordination polymers were synthesized using H₃imdc and 4,4’-bipyridine as ligands:{[LnZn₂（imdc）₂（4,4’-bpy）₂（H₂O）₅]（OH）}_n（Ln=Eu（1）,La（2））,{[LnZn₂（imdc）₂（4,4’-bpy）₂（H₂O）₄]（OH）}_n（Ln=Tb（3）,Sm（4）,Gd（5））. The structure shows that the complexes 1-5 are all three-dimensional framework structures with channels,and all have good thermal stability and pH fluorescence stability.Fluorescence detection research shows that both complexes 1 and 3 can be used as highly selective and highly sensitive multifunctional fluorescent sensors for Fe³⁺ions,pentavalent vanadate anions,nitrobenzene molecules and tryptophan molecules,and can be used in aqueous solutions to achieve qualitative and quantitative detection of the above test objects.The IR,PXRD,UV-vis absorption spectrum,and fluorescence lifetime have been used to systematically study the fluorescence 3 can be developed into potential fluorescent sensors with practical use value in aqueous solutions.2.Using Hpbca ligand to react with transition metal salt,a one-dimensional zigzag chain coordination polymer was constructed in the water/ethanol solvent system:{[Cd（pbca）₂]·2C₂H₅OH}_n（6）,6 formed a three-dimensional supramolecular structure through hydrogen bonding andπ···πinteractions.Studies have shown that it has excellent thermal and pH fluorescence stability.The properties of fluorescent probes indicated that 6 can qualitatively and quantitatively detect Zn²⁺ion,CO₃^2-ion,lysine and arginine molecules through fluorescence enhancement,and detect 2,4,6-trinitrophenol（TNP） through fluorescence quenching.The experiment found that the complex 6 has excellent anti-interference and recyclability.At the same time,the fluorescence response mechanism of complex 6 to different analytes is elucidated.3.A dual-nuclear transition metal complex was synthesized from Hpbca ligand:[Zn₂（pbca）₂（SO₄）（H₂O）₃]（7）,which formed a three-dimensional supramolecular structure through hydrogen and π···πinteractions.In addition,the IR spectrum,elemental analysis,thermal stability,PXRD and luminescence properties of complex 7 were investigated respectively.