Application Of Coumarin-based Fluorescent Probes In The Detection Of Heavy Metal Ions

In the long history of human development,heavy metals are widely used in daily production and life.Due to the limitations of early science and technology,people did not fully understand the dangers of heavy metals,resulting in a large amount of heavy metal ions being discharged into the environment.A series of diseases caused by heavy metals broke out in the last century,reaching millions of people,and people began to pay attention to the impact of heavy metal pollution on the environment.Although countries around the world have issued a series of laws and regulations to regulate the discharge of heavy metals,illegal traders still secretly emit them.Because heavy metals are difficult to be decomposed by the environment and are easily accumulated into the human body through the food chain,it endangers human health and life safety badly.A fast,efficient and convenient detection method to detect heavy metal ions was in urgent need.Among the many heavy metal ions,mostly harmful Hg²⁺,and widely used Cu²⁺is the two heavy metal elements that need to be detected.Traditional detection solutions are difficult to response for emergency detection on a large scale due to the expensive equipment and its poor mobility.Fluorescent probes which possess the advantages of being portable,efficient,and inexpensive,are one of the most promising methods for heavy metal detection,and have attracted widespread attention from the researchers.Coumarin-based fluorescent probes are promising detection solutions for fluorescent probes due to their stable physical properties and high quantum yield.This paper is mainly composed of the following three aspects:1.Based on the desulfurization reaction promoted by Hg²⁺,a coumarin-based Hg²⁺detection fluorescent probe T1 was designed and synthesized.Probe T1 still has good detection performance in pure water.The fluorescence intensity can be increased by 3 times after adding Hg²⁺.Probe T1 has a very wide p H adaptability,which can response to Hg²⁺both in acid and alkali environment,that has good detection performance in the range of p H 3-10.It is sensitive to Hg²⁺detection,the detection limit reaches 0.14μM.When the Hg²⁺concentration is in the range of 5×10^-6M to 2.5×10^-5M,the fluorescence emission intensity of probe T1 has a good ratio with the Hg²⁺concentration.At the same time,probe T1 also has very good selectivity and anti-interference ability.2.A coumarin-based Hg²⁺detection fluorescent probe T2 was designed and synthesized based on the hydroxymercuration reaction.The probe T2 has good detection ability in water enviro nment,and its neutral energy is the strongest in pure water environment.After Hg²⁺is added,the fluorescence emission intensity can be increased by 20 times.The special structure design makes the probe T2 have very efficient and sensitive detection performance.In pure water environment,it only takes 15 minutes to complete the detection,and the detection limit is as low as 84n M.Lastly,we also studied the selectivity and anti-interference performance of the probe,and discussed the detection mechanism of probe T2.3.A coumarin-based Cu²⁺fluorescent probe T3 was designed and synthesized based on the coordination cleavage reaction.Probe T3 can response to Cu²⁺on variable environment,completely overcoming the weakness that organic solvent environment was necessary in the detection process,and Cu²⁺can be identified and detected in pure water environment.Due to the particularity of the recognition mechanism,the detection of Cu²⁺by probe T3 is very fast,which can be completed within 20 minutes,and makes probe T3 have good selectivity and anti-interference ability.