Preparation And Properties Of Reaction-base Fluorescent Probes For Copper(Ⅱ) And Mercury(Ⅱ) Ion

Fluorescent probes are widely used in the fields of environmental detection,food safety and biological imaging due to their advantages of simple operation,high sensitivity,good selectivity,rapid real-time analysis and high spatial and temporal resolution.Agricultural products are the source of food,the quality and safety of agricultural products are related to the people’s health and life safety,and the quality and safety of agricultural products have a direct dependence on the environment of the origin of agricultural products.In recent years,with the rapid development of Chinese industry and the excessive application of pesticides and fertilizers in the agricultural production process,the heavy metal pollution in the production environment of agricultural products is becoming more and more serious,which has become a prominent problem limiting the sustainable development of agriculture in China.The research on key technologies for rapid detection of heavy metals in the environment of agricultural production areas should be carried out.It is of great significance to the environmental management of agricultural production area,the traceability of agricultural supply chain and the quality and safety of agricultural products.In this thesis,four highly sensitive and selective reactive fluorescent probes were designed and synthesized to selectively identify copper ions(Cu²⁺)or mercury ions(Hg²⁺).Some of the probes successfully achieved the detection of Cu²⁺or Hg²⁺in irrigation water of agricultural origin environment.Specific studies include the following:1.A novel colorimetric and ratiometric fluorescent probe C-1 with hemicyanine as the fluorophore and pyridinecarboxylate as the recognition group for Cu²⁺was designed and synthesized.The absorption spectra and fluorescence spectra of C-1 are obviously changed by Cu²⁺,and Cu²⁺can be selectively detected without interference from other metal ions.The recognition of Cu²⁺by C-1 has the advantages of short response time（2min）,low detection limit（0.62μM）,specific selectivity and anti-interference.Therefore,C-1 can detect trace Cu²⁺in pure water solution,and has been applied to the detection of Cu²⁺in irrigation water of agricultural production area.2.A novel Hg²⁺fluorescent probe H-1 was designed and synthesized with 3-hydroxyphthalimide derivative as the fluorophore and diphenylthiophosphinate as the recognition group.The recognition mechanism is that Hg²⁺promoted the desulfurization reaction of H-1,which was verified by UV-Vis,fluorescence spectroscopy and mass spectrometry.H-1 has the advantages of good selectivity,low detection limit（18.7 n M）and large Stokes shift（195 nm）for the detection of Hg²⁺.Meanwhile,the color of the solution changed from non-fluorescent to green under a 365 nm UV lamp irradiation,and the naked-eye recognition of Hg²⁺was achieved.3.A novel Hg²⁺fluorescent probe H-2 was synthesized based on the ESIPT mechanism.Due to the inhibition of ESIPT by diphenylthiophosphinate,H-2 itself is non-fluorescent.After adding Hg²⁺,Hg²⁺promoted the desulfurization hydrolysis of diphenylthiophosphinate,released hydroxyl group,restored ESIPT and enhanced fluorescence.Meanwhile,the detection of Hg²⁺by H-2 not only has the advantages of good selectivity,low detection limit（0.49μM）and obvious change of fluorescence emission（about 17-fold enhancement）,but also has a large Stokes shift（195 nm）,and the change of solution fluorescence color from non-fluorescence to green can be observed nakedly under a 365 nm UV lamp irradiation,which has potential application prospects.4.A ratiometric fluorescent probe H-3 for Hg²⁺was developed based on ICT,which included hemicyanine as the fluorophore and diphenylthiophosphinate as the recognition group.The ICT effect of H-3 is weaker due to the introduction of diphenylthiophosphinate which weakens the electron-giving ability of the hydroxyl group.After the addition of Hg²⁺,diphenylthiophosphinate is hydrolyzed,which enhances the electron-giving ability of hydroxyl group and makes the ICT effect stronger.H-3 is not only capable of ratiometric measurements of Hg²⁺,but also has the advantages of low detection limit（13.2n M）,specific selectivity and interference resistance.At the same time,the fluorescence color of the solution can be observed from non-fluorescence to green under a 365 nm UV lamp irradiation with naked eyes,and successfully applied to the detection of Hg²⁺in irrigation water of agricultural origin environment.