Water-Dispersed And Water-Stable Amorphous Nano Rare Earth Salicylate Complex Fluorescent Probe

Methyl salicylate?MS?and its derivatives are a class of keto tautomeric compounds widely found in plants.They not only show good bactericidal,anti-inflammatory,antipyretic,analgesic and antiviral properties.It is pharmacologically active and emits blue due to the intermolecular hydrogen bond proton transfer?ESIPT?of its o-hydroxybenzoyl structural unit to produce a ketone tautomer,which has great potential for application in information storage and environmental detection.Studies on the synthesis and fluorescence characteristics of salicylate complex crystals and their studies on the synthesis of oxide powders have been reported.In this study,work has been carried out to improve its application performance and reduce the cost of synthesis.A complex with high dispersion and high fluorescence stability synthesized by water has been developed and used as a chromium ion fluorescent probe.At the same time,the application potential in the preparation of nanocomposite rare earth oxide functional materials was also studied.In this study,A-MS-Tb was synthesized by one-pot method,and theMethyl salicylate complex?A-MS-Tb?synthesized directly in aqueous solution was an amorphous nanoprecipitate with a particle size between 50 nm and 100 nm.It has a composition similar to the reported crystal complex.The complex exhibited strong fluorescence emission at 494,549,591,625 nm and a ⁵D₄?⁷F_J?J=6,5,4,3?energy level transition attributed to Tb³⁺.A significant difference between A-MS-Tb and crystalline complexes is their suspension stability and fluorescence stability in water,which is important for their use as fluorescent materials and ion sensors.In particular,when Cr³⁺is added to its aqueous suspension solution,its green fluorescence can be quenched.Accordingly,a fluorescent probe for highly sensitive determination of Cr³⁺concentration in the solution was constructed.The sensitivity of this fluorescent probe was 35 nM,and its selectivity and anti-interference ability were evaluated.Because MS can coordinate well with Tb³⁺,and its coordination ability with other Ln³⁺is weak,it is difficult to observe their characteristic peaks.Based on this,we use Tb³⁺as a bridge to observe the change of the emission peak of Tb³⁺by introducing other Ln³⁺.Through experiments,we found that the addition of Dy³⁺,Er³⁺,Eu³⁺,Gd³⁺,Ho³⁺,Lu³⁺,Sm³⁺,Tm³⁺,Y³⁺,Yb³⁺is not the same.The introduction of Dy³⁺,Er³⁺,Ho³⁺,Lu³⁺,Sm³⁺,Tm³⁺,Y³⁺,Yb³⁺has a coordination with the ligand,but has no obvious effect on the peak of Tb³⁺;with the introduction of Lu³⁺,the green light of Tb³⁺is slightly weakened;the introduction of Gd³⁺not only weakens the characteristic peak of Tb³⁺but strengthens it;By adding Eu³⁺,the energy transfer between Tb³⁺and Eu³⁺is realized,thereby realizing the illumination of Eu³⁺.These materials show good luminescent stability and self-dispersing properties in aqueous solution.The color of MS-Tb/Eu can be successfully adjusted by changing the ratio of Tb³⁺to Eu³⁺.In addition,by adding Cr³⁺to the aqueous suspension of the complex,the red luminescence of Eu³⁺is more easily quenched,and the emission spectrum of Tb³⁺does not change significantly.Therefore,the sensor of Cr³⁺was successfully constructed.The MS-Tb/Eu sensor is more stable than the MS-Tb and has a wider linear range.This study provides a scientific basis for further broadening the scope of chemical sensing research and establishing increasingly sensitive new detection methods.Based on the mismatch between the energy levels of MS and Eu³⁺,the characteristic spectrum of Eu³⁺cannot be emitted.The introduction of cerium nitrate can enhance the fluorescence of ligand MS and form a methyl salicylate ruthenium complex.The synthesized complex precursor is an amorphous structure.Compared with the synthesis method of the crystalline complex,in the experiment,we found that the fluorescence intensity is best when the doping concentration is 10%mol and the temperature is 1100?.the preparation method is simpler.The synthesized precursor is placed in a microwave muffle furnace for calcination,and Y₂O₃:Eu is obtained by thermal decomposition.