Design,Synthesis And Properties Of Fluorescent Probes For Detecting Metal Ions

Metal ions play an important role in various industrial reactions and physiological processes,and they are crucial to the survival of human,plants and animals.However,excessive intake of some metal ions can cause many diseases and environmental problems.Therefore,the detection of metal ions is very important.In this paper,based on the current research status of metal ions,three fluorescent probes for the detection of metal ions were designed and synthesized,and their application value was studied from the aspects of synthetic characterization,spectroscopic testing and DFT theoretical calculations,respectively.First,a phenanthro[9,10-d]imidazole based“turn-on”fluorescence sensor（P1）was synthesized by 4-hydroxy-3-nitrobenzaldehyde and 9,10-phenanthrenequinone to detect Hg²⁺.In DMF/PBS buffer solution,probe P1 showed high selectivity and anti-interference ability against Hg²⁺.After adding Hg²⁺,the fluorescence intensity of the probe solution was enhanced,and the fluorescence changed from colorless to blue.The detection limit of the probe for Hg²⁺was 45.76 n M.The response mechanism of the probe was proposed by nuclear magnetic titration and nuclear magnetic two-dimensional spectrum,and the mechanism was explained by density functional theory（DFT）calculation.The probe was applied to the monitoring of Hg²⁺in real environmental water samples with good results.Second,a fluorescence probe P2 for detection of Al³⁺was synthesized by connecting salicylaldehyde group to isoferone derivatives and using salicylaldehyde part as recognition group.In THF/PBS buffer solution,probe P2 had high sensitivity to Al³⁺（detection limit was6.6527 n M）and fast response（less than 1 min）.After adding Al³⁺,the visible solution changed from orange to pink with enhanced fluorescence intensity.The identification mechanism of probe P2 was explained by density functional theory（DFT）calculation.The successful application of probe P2 to the detection of Al³⁺in actual water samples provided a possibility for the application of P2 in environmental research.Third,a Schiff base"on-off"fluorescent sensor（P3）was designed and synthesized with tricyanodihydrofuran derivatives as fluorophores.In DMF/PBS buffer solution,the probe P3can selectively bind to Cu²⁺,and had good anti-interference ability.The presence of other ions hardly interferes with the detection of Cu²⁺.The color of the probe changes from purple to dark blue in response to Cu²⁺,which can be seen by naked eyes.It was an ideal fluorescence sensor.The probe had low synthesis cost,high sensitivity and low detection limit.It was used for the detection of trace amounts of Cu²⁺in water samples and the recovery rate was good.