In recent years,due to the rapid development of society and the continuous improvement of living standards,people are more and more concerned about the problem of pollution.The problem of chemical reagent residues caused by the vigorous development of industry is a hot topic,which arouses the research interest of researchers.The residues of organic solvents and heavy metal ions are often invisible to the naked eye,so a recognition system that is easy to detect and observe is needed.Metal-organic complex is an organic-inorganic hybrid material composed of two parts--metal ions and organic ligands connected by coordination bonds.Due to the particularity of this hybrid material and the special pore size and three-dimensional characteristics inside the material,researchers focus on the metal-organic framework materials with considerable application range,special molecular pore size and special chemical properties of the atomic center,can be used as adsorption materials,luminescent materials or biomedical materials.Luminous metal-organic frame(LMOFs)materials are branch materials of metal-organic frame materials.They are often used for detection and recognition because of their special fluorescent luminous properties and are applied to sensor materials.It is reasonable to use LMOFs material to identify contaminated ions.In this paper,according to the characteristics of LMOFs,a fluorescent probe with special luminescence was designed and synthesized to detect and recognize contaminated ions.Firstly,a series of nitrogen-oxidized nicotinic acid ligands were selected as the bridging organic ligands.To design and synthesize complexes with special luminescence properties,lanthanide metals with special luminescence properties are the only choice.Therefore,lanthanide metal can be used as the metal part of the complex.In this paper,18 cases of lanthanide metal-organic complexes were successfully constructed under solvothermal conditions by using niacin treated with nitrogen oxidation as organic ligand:{[Ln(HNNO)2(NO3)](DMF)2}n(Ln=Sm(1),Gd(2),Tb(3)),{[Nd(HNNO)2(NO3)(DMF)](DMF)}n(4),{[Eu(HNNO)10(NO3)2(DMF)](DMF)2(H2O)8}n(5),{[Ln(HNNO)6(NO3)](DMF)(H2O)}n(Ln=Sm(6),Eu(7),Gd(8),Tb(9),Dy(10),Ho(11)),{[Ln2(HNNO)7(NO3)(Cl2)(CH3CN)2](DMF)}n(Ln=Ce(12),Pr(13),Nd(14)),{[Ln(HNNO)7(Cl)]}n(Ln=Eu(15),Gd(16),Tb(17)),{[Ce(HNNO)6(NO3)](H2O)3}n(18).Then,a series of basic properties of the 18 complexes were characterized by X-ray single crystal diffraction,thermal stability test,infrared spectroscopy test and X-ray powder diffraction.X-ray powder diffraction test results showed that the phase purity of 18 complexes was very high,which could be used for further testing.On this basis,four complexes 5,7,9,15 with excellent properties were selected.The solid fluorescence test results of the complexes showed that the solid samples showed specific fluorescence luminescence characteristics under different excitation wavelengths.Based on these results,it is indicated that complexes 5,7,9,15 can be used as fluorescent probe materials.Then,the detection and recognition of organic solvents of complexes 5,7,9,15 were investigated.The test results showed that all the four complexes could be used as fluorescent probes to identify nitrobenzene solvent,and the detection limit of nitrobenzene of the four complexes was not more than 50 μmol/L.The results show that complexes 5,7,and 15 can be used as fluorescent probes for chromium(Cr3+)ions,and europium complex 9 can be used as fluorescent probes for iron(Fe3+)ions.The detection limit of nitrobenzene in four cases was not more than 50 μmol/L.Complexes can be used as fluorescent probes to identify special ions,because the photoelectron transition from metal to ligand in the complex emits special red or green fluorescence.During recognition,the presence of special ions(nitro group,chromium ion,iron ion)will quenching the fluorescence luminescence of the system,changing the color of the system,and thus knowing the concentration of special ions in the system.The experimental results show that lanthanide organometallic complexes can be used as fluorescent luminescence sensors for special materials,which is a strong candidate for luminescence recognition of organometallic frames.Although LMOFs-based sensors exhibit excellent special fluorescent luminescence properties under laboratory conditions,their commercial application is limited due to cost and complexity of synthesis,so further research and development is still needed. |