Syntheses,Structures And Properties Of Coordination Polymers Based On 9,10-Anthracenedicarboxylic Acid

Coordination polymers（CPs）are a kind of functional network materials,which are self-assembled by metal ions or metal clusters and organic ligands（oxygen or nitrogen atoms）through coordination,and arranged in space according to periodic rules.As an organic/inorganic hybrid material,coordina-tion polymers are composed of organic and inorganic parts.According to this characteristic,the co-ordination polymers have the advantages of both inorganic and organic materials.Therefore,coordi-nation polymers have great potential in the fields of gas storage/separation,magnetism,catalysis and luminescence.In this paper,based on 9,10-anthracene dicarboxylic acid（H₂L）and 1,10-phenanthroline（phen）ligand,two novel coordination polymers were successfully prepared by solvothermal or liquid phase diffusion method with rare earth metal ions and transition metal ions.The crystal structure,phase purity,chemical stability and thermal stability of the complexes were characterized by single crystal XRD,powder XRD,thermogravimetric analysis and infrared spectroscopy.At the same time,the fluorescence properties of the complexes were investigated by fluorescence spectroscopy,transient fluorescence spectroscopy and theoretical calculation,so as to further study the effects of metal ions,antibiotics and food additives on the fluorescence of the complexes.The main research results of this paper are as follows:1.The organic ligands 9,10-anthracene dicarboxylic acid and 1,10-phenanthroline were reacted with rare earth metal ion Eu³⁺under high temperature and high pressure by solvothermal method,and a coordination polymer[Eu L_1.5（phen）（H₂O）]_n（1）with three-dimensional network structure was suc-cessfully synthesized.In complex 1,the carboxylate of the L^2-ligand connects the metal ions through theμ₂ bridging coordination mode to form a bridging dinuclear Eu₂（COO）₄unit.At the same time,the carboxylate groups of the L^2-ligand are connected to each other by theμ₄-bridged coordination mode and the dinuclear metal unit to form a two-dimensional square network,and further connected by theμ₄-L^2-ligand to form a three-dimensional structure.The complex has extremely high chemical stability in different organic solvents and aqueous solutions with p H of 1-8.The experimental results show that complex 1 can selectively sense Zr⁴⁺ions in aqueous solution,and Zr⁴⁺ions show a quench-ing response to the fluorescence of 1-H₂O suspension.When the concentration of Zr⁴⁺ions is in the range of 0-15μM,the fluorescence intensity of complex 1 shows an excellent linear relationship with the concentration of Zr⁴⁺ions.The fluorescence quenching constant K_svis 53830 M^-1,and the detection limit and quantitative limit are 167 n M and 501 n M,respectively.This indicates that com-plex 1 can be used as a fluorescent sensor for detecting Zr⁴⁺ions in aqueous solution.Finally,the mechanism of complex 1 detecting Zr⁴⁺ions was carefully explored.2.A supramolecular three-dimensional coordination polymer[Cd（L）（DMF）₂（H₂O）₂]_n（2）was suc-cessfully prepared by the reaction of organic ligand 9,10-anthracene dicarboxylic acid with transition metal ion Cd²⁺at room temperature by liquid phase diffusion method.In complex 2,the carboxylate group in the L^2-ligand is connected to the Cd²⁺ion through a monodentate coordination mode to form a one-dimensional chain structure with an infinite extension of the c-axis.The one-dimensional chain structure is interconnected by strong hydrogen bonds to form a three-dimensional structure.The com-plex emits strong blue-purple light,and its maximum characteristic emission peaks are located at 424nm and 448 nm,respectively.In the selective experiment of antibiotics,moxifloxacin showed a very obvious fluorescence quenching effect on 2-DMF suspension.In the low concentration range of 0-50μM,the fluorescence intensity of complex 2 at 424 nm showed a good linear relationship with the concentration of moxifloxacin.The fluorescence quenching constant K_sv was 24280 M^-1,and the limit of detection and limit of quantitation were 0.892μM and 2.97μM,respectively.In the selectivity experiments of anions and substances in food,sodium hexametaphosphate showed a very obvious fluorescence enhancement response to 2-DMF suspension.When the concentration of sodium hex-ametaphosphate was in the range of 0-25μM,the fluorescence intensity of complex 2 at 448 nm showed a good linear relationship with the concentration of sodium hexametaphosphate.The fluores-cence enhancement constant K_EC was 85532 M^-1,and the limit of detection and limit of quantitation were 105 n M and 352 n M,respectively.The above experimental results show that complex 2 can be used as a multi-responsive fluorescence sensor for moxifloxacin and sodium hexametaphosphate.Finally,we discussed the possible detection mechanism of complex 2.