Synthesis And Performance Study Of Coordination Polymers Based On Dipyridine Tetracarboxylic Acid Ligands

Since the emergence of coordination polymer materials,the preparation and performance exploitation of coordination polymer materials have attracted more and more attention of researchers.As one of the excellent ligands for the construction of coordination polymers,pyridine carboxylic acid ligands have good bridging,chelating ability and modifiability.The coordination polymers of these ligands have good stability and excellent optical properties,so they are widely used in many fields,such as fluorescence sensing,dye adsorption,catalysis and medical treatment.In this thesis,five coordination polymers with two multidentate ligands were synthesized using 2,6-dicarboxylic acid as terminal group.On the basis of detailed characterization,fluorescence sensing,dye adsorption and catalytic CO₂ cycloaddition reaction were studied.The research work of this paper is divided into the following six parts:1.The synthesis of pyridine carboxylic acid coordination polymers and its research progress in fluorescence recognition,dye adsorption and catalysis are reviewed.The purpose and significance of this dissertation are also expounded.2.Anovelbipyridine-tetracarboxylateligandH4L^I（（4-（2,6-dicarboxypyridin-4-yl）methoxy）pyridine-2,6-dicarboxylic acid）was synthesized.New coordination polymers,Ln-L^I（{[Ln（HL^I）（H₂O）]·DMF·4H₂O}n,Ln=Eu:Eu-L^I,Tb:Tb-L^I）were afforded solvothermally with the ligand reacting with rare earth nitrates,Ln（NO₃）₃·6H₂O（Ln=Eu,Tb）,at high temperature.These coordination polymers were characterized by infrared（IR）spectroscopy and scanning electron microscope-electron energy spectroscopy（SEM-EDS）.Solid state fluorescence test showed that Ln-L^I had good characteristic luminescence of rare earth ion.Fluorescence sensing studies showed that Eu-L^Iand Tb-L^I could produce selective fluorescence responses to Cu²⁺,Cr O₄^2-,picric acid（PA）and tryptophan（Try）in aqueous medium with low detection limits.Finally,the recognition mechanism was studied.3.The coordination polymer（Cu2L^I）n（{[Cu₂L^I）]·2H₂O}_n)was obtained by solvothermal method between H4L^I and Cu（NO₃）₃·6H₂O.Structural analysis showed that（Cu2L^I）n was a two-dimensional wavylike plane structure,and the coordination water of two adjacent copper ions was located upper and under the plane.In addition,Three-dimensional hydrogen-metal-organic skeleton was formed by intermolecular hydrogen bonding.The study of catalytic performance showed that（Cu2L^I）n,as a solvent-free catalyst for CO₂cycloaddition reaction,had good catalytic performance,and the catalytic mechanism was explored.4.A Er metal organic framework,Er-MOF was synthesized using benzene p-substituted bispyridine tetracarboxylic acid ligand H4L^Ⅱ（Benzon-substituted 2,6-pyridine dicarboxylic acid）.Structural analysis showed that Er-MOF had good structural stability,large specific surface area and oxygen-rich hexagonal holes.The adsorption of organic dyes showed that Er-MOF had excellent adsorption properties for organic dyes methylene blue（MB）and malachite green（MG）in aqueous medium.On this basis,the adsorption isotherm model,adsorption kinetics model,adsorption desorption performance and adsorption mechanism were studied.5.Taked into account the current limitations of the sensing materials,the known Zn^Ⅱcoordination polymer（ZnCP）of structure was chosen to be doped with polymethyl methacrylate（PMMA）to prepare ZnCP@PMMA membranes.It was characterized by infrared and SEM,etc.Studies showed that the film had good water stability and excellent optical properties.The fluorescence sensing research showed that the luminescent film had a good recognition effect on PA,and its quenching mechanism is studied.6.Summary and Outlook:This dissertation provides some data support and theoretical guidance for the synthesis,fluorescence sensing,dye adsorption and catalytic CO₂cycloaddition of dipyridine tetracarboxylic acid ligand.