Construction And Luminescent Regulation Of Lanthanide Coordination Polymers Based On Aromatic Carboxylic Acid

The luminescent rare earth coordination polymer has the advantages of bright luminous color,visible to the naked eye,high color purity,long life and high emission quantum yield,etc.,so it has a wide range of applications in lighting,display,optical sensing,luminescence detection,laser and other fields.In this thesis,based on the principles of coordination chemistry and the idea of design synthesis,organic carboxylic acid ligands containing different aromatic rings and the number of coordination sites were selected as linker,and water / solvothermal methods were used to control the reaction conditions.Twenty-six cases of rare earth coordination polymers were prepared.The structures of rare earth coordination polymers were determined using single crystal X-ray diffraction analysis,infrared spectroscopy analysis,elemental analysis,powder X-ray diffraction analysis,etc.,and rare earth coordination polymerization was studied through emission spectroscopy,luminescence lifetime,and energy transfer process analysis.The properties of the substance,with the methods of PMMA doping,ion doping,and guest molecule introduction,the application of rare earth coordination polymers i n adjustable luminescence,ion detection and luminescence enhancement were explored.With 2,3-pyridinedicarboxylic acid?H₂pydc?as the main ligand,a three-dimensional rare earth coordination polymer {[Eu₂?pydc?₃?H₂O?]·2H₂O}n?1?and seven cases of one-dimensional chain rare earth coordination polymers [Ln?pyc?₂?Hpyc??NO₃?]n?Ln = Nd?2?,Sm?3?,Eu?4?,Gd?5?,Tb?6?,Ho?7?,Er?8??were prepared by synthesizing different metal salts under different solvent conditions.The coordination polymer 1 is connected by organic ligands in three different coordination modes to form a tight three-dimensional network structure with a centrally symmetric four-core structural unit.Coordination polymers 2-8 are one-dimensional chain-like structures with triple helix chains formed by a single ligand connection,and the chains are further stacked into a three-dimensional supramolecular structure through hydrogen bonding.The solid-state luminescence test showed that the coordination polymers 1 and 4 showed red luminescence visible to the naked eye,and 6 showed green luminescence visible to the naked eye.The rare earth coordination polymers 1,4,6 are incorporated into the PMMA matrix to prepare a luminescent film material.The PMMA matrix can interact with the coordination polymer to further improve the luminescence performance of the coordination polymer.The optimal doping ratio is 4%.The luminescence intensity of the prepared PMMA film is increased and the life is extended accordingly.Films with tunable white luminescent properties were prepared by co-doping coordinating polymers 4,5,6 with different luminescent colors into the PMMA matrix.As the excitation wavelength changes,the intensity of Eu³⁺ and Tb³⁺ ion emission also changes based on the ligand.W?4,5,6?-PMMA has a shorter Tb?III?luminescence lifetime,but Eu?III?has a longer luminescence lifetime,indicating that there is energy transfer between rare earth ions,the energy transfer efficiency??ET?from Tb³⁺ to Eu³⁺ ion is about 29.9%.Using V-dicarboxylic acid H₂ cpon as the main ligand,coordination polymers {Ln?cpon??Hcpon??H₂O?₃}n?Ln = Tb?9?,Eu?10??were prepared by controlling the reaction conditions.Structural analysis of coordination polymers 9 and 10 shows that each zigzag chain is connected by strong hydrogen bonds,? ·· ? stacking,and C–H ··· ? interaction to form a tight three-dimensional supramolecular skeleton.Coordination polymer 9 has a good photostability in aqueous solution,and can detect Cr₂O₇^2-ion in aqueous solution very sensitively in a low concentration range?Ksv = 4.11 × 104 M-1?.Membrane material 9-PMMA has a good recognition ability for Cr₂O₇^2-ions,and greatly improves the sensitivity to Cr₂O₇^2-ions.Its quenching coefficient Ksv is as high as 5.2 × 104 M-1,and the detection limit is as low as 5.6 ppb.And the film also has good recyclability and anti-interference ability to other ions.Using 1,3,5-tris?4-carboxyphenoxy?benzene?H₃tpob?with a symmetric structure as the research object,coordination polymers [Ln?tpob??DMF??H₂O?]n?Ln = Nd?11?,Sm?12?,Eu?13?,Gd?14?,Tb?15?,Dy?16??were prepared by reaction with different metal salts.The structural analysis of the coordination polymers 11–16 shows that the one-dimensional chains are connected by ? ·· ? stacking interactions to form a compact three-dimensional supramolecular skeleton.The halide perovskite quantum dots CH₃NH₃ PbBr₃ were encapsulated in the pores of the coordination polymer 13 by in-situ synthesis to obtain CH₃NH₃ PbBr₃@13 composite material,which showed different luminescence at different excitation wavelengths.The CH₃NH₃ PbBr₃@13 composite material was further encapsulated in PMMA matrix.The obtained film material can realize the adjustable light emission from red light to green light,and finally the stability of CH 3NH₃ PbBr₃ quantum dots is greatly improved.Coordination polymers {[Eu?Htpo??NO₃??H₂O?]·H₂O}n?17?,{[Ln?Htpo??NO₃??H₂O?]·?CH₃CN?·2?H₂O?}n?Ln = Eu?18?,Tb?19?,Gd?20?,Sm?21?,Dy?22?,Nd?23??,{[Eu?tpo??HCOO?0.5]·?H₃O?0.5}n?24?,{[Eu?tpo??DMF?]·?solv?x}n?25?,{[Eu?tpo??DMA?]·?solv?x}n?26?were prepared using rigid tri-p-carboxyphenylphosphine oxide?H₃tpo?containing multiple coordination sites as the main ligand and adjusting the reaction solvent and temperature.Coordination polymers 17–26 exhibit three different topological types.The structure of the coordination polymer 17 is flexible,and can be obtained by solvent-induced single crystal to single crystal?SC-SC?conversion involving configuration conversion of organic ligands 18.During the structural transformation process,the vibration and rotation of the chemical bond based on the ligand's phosphorus center promoted the mutual conversion between 17 and 18.The solid-state luminescence of the coordination polymer 17 can be enhanced by incorporating non-luminescent metal ytterbium ions.Yb?III?can transfer the absorbed energy to Eu?III?ions through the anti-Stokes process,and promote the luminescence of Eu?III?ions.The total sub-yield ?overall of Eu0.88Yb0.12 tpo is 37.5%,and the ligand sensitization efficiency is 67.3%.