Study Of Post Modification Synthesis And Fluorescent Sensors Of Coordination Polymers Based On Pyridine Containing Polycarboxylic Acid Ligands

The post-modification synthesis method of MOFs as a conventional modification method has gradually become one of the current research hotspots.In this thesis,the three-dimensional coordination polymer[Cd（Hdpcp）]_n（Cd-MOF）was used as the raw material,and the photoluminescence composite material Eu@Cd-MOF was obtained（H₃dpcp was 3-（2,4-dicarboxyphenyl）-6-carboxypyridine）.The research focuses on its potential application as a fluorescent probe to specifically identify food additives and nitro aromatic explosives.In addition,a three-dimensional supramolecular coordination was synthesized using4-（pyridine-3-oxy）-phthalic acid（H₂ppda）as the main ligand and4,4’-biphthalic acid（H₂bpdc）as the auxiliary ligand.Compound[Eu（ppda）（bpdc）_0.5（C₂H₅OH）（H₂O）]_n（Eu-1）,and studied the fluorescent probes of Eu-1 for folate,arginine,lysine and tartrazine in detail nature.The main research results of this thesis are as follows:1.Through the method of post-modification synthesis,Eu³⁺ions are loaded on the coordination polymer with unsaturated carboxyl sites[Cd（Hdpcp）]_n（Cd-MOF）to obtain a modified MOF composite material,Eu@Cd-MOF.The structure and properties of Eu@Cd-MOF were characterized by a series of methods such as infrared,ultraviolet-visible spectroscopy,thermogravimetric analysis,X-ray powder diffraction and X-ray photoelectron spectroscopy.In addition,fluorescence exploration experiments show that Eu@Cd-MOF has good fluorescence stability and structural stability in different p H aqueous solutions.At the same time,the study found that the food additives sodium salicylate,sodium dehydroacetate,explosive 2,4,6-trinitrophenol（TNP）and other three analytes can effectively quench the Eu³⁺in the composite Eu@Cd-MOF Ionic characteristics emit light.Experimental studies on the mechanism of fluorescence quenching show that the carboxylic acid group in sodium salicylate inhibits the formation of Eu-O coordination bonds in the composite material,leading to fluorescence quenching;for TNP,UV competitive absorption leads to Eu@Cd-MOF is the main reason for fluorescence quenching.In addition,Eu@Cd-MOF’s excellent anti-interference and cycling ability demonstrated its potential practical value as a fluorescent probe.2.Obtain Eu-1 crystals by hydrothermal synthesis.The different fluorescence response behaviors of Eu-1 to folic acid,amino acid molecules and common food additive molecules were studied in detail.Studies have found that Eu-1 has the characteristic emission of trivalent europium ions and good p H luminescence stability.Fluorescence probe experiments show that Eu-1 has high fluorescence quenching efficiency for folic acid,arginine,lysine and tartrazine,as well as good selectivity and circulation.Through the experimental characterization of infrared spectroscopy,ultraviolet-visible absorption spectroscopy,X-ray powder diffraction,X-ray photoelectron spectroscopy,and fluorescence lifetime,the selective fluorescence quenching mechanism of Eu-1 in the presence of different analytes is systematically made Elaboration.Based on the above research,it is explained that Eu-1 can be used as a multifunctional"turn on-off"fluorescence detector in a water environment.