Preparation and fluorescence properties of functionalized rare earth europium complexes
To obtain functionalized rare-earth complexes containing reaction sites,two functionalized rare earth europium complexes were prepared in ethanolic solution by using a low-temperature isocratic solvothermal method with the rare earth Eu3+as the central ion,and by adding aliphatic carboxylic acid,aromatic carboxylic acid ligands and the co-ligand 1,10-phenanthroline,respectively.The elemental composition and structure of the rare earth complexes were determined by elemental analysis and spectroscopy,the thermal stability and fluorescence properties of the two complexes were compared and the effects of different pH values on the fluorescence intensity of the complexes were investigated.The results show that the thermal stability of the two complexes is good,and the onset decomposition temperature is above 200℃.The prepared complexes can both emit strong characteristic red light under UV excitation.The fluorescence intensity of the functionalized rare earth complexes with aromatic carboxylic acids is higher,1.5 times higher than that of the aliphatic carboxylic acids,and the fluorescence lifetimes reach 0.55 ms and 1.4 ms,respectively.When the pH of the acidic solution decreases from 7 to 2,the fluorescence intensity of the aliphatic carboxylic acid complexes decreases from 8.1×105 to 2.6 × 105 and that of the aromatic carboxylic acid complexes decreases from 4.4 × 106 to 3.4 × 106.The functionalized rare earth complexes with hydroxyl group as the reaction site prepared in this study have high fluorescence intensity and lifetime,and are expected to be applied to the rapid detection of acidic solutions.
organic rare earth complexeseuropiumfunctional hydroxylfluorescence intensitypH value
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