The Design,Synthesis,and Application Of Fluorescent Probes For The Detection Of Mercury Ions

Mercury is widely distributed and one of the most toxic heavy metals.Mercury ions are not biodegradable and can accumulate in the body through the food chain.Especially in children early stages of development,even low concentrations of mercury are easily affected and lead to various diseases related to the kidneys,brain and central nervous system.Therefore,the detection of mercury in environmental and biological samples is critical for the determination of environmental pollution and the diagnosis of clinical diseases.Compared with traditional detection methods,fluorescent probes are widely used in the field of analysis due to their convenient application,good cell membrane permeability and high sensitivity to trace analytes.This paper is based on the fluorescence detection method designed and synthesized three fluorescent probes for detecting Hg²⁺:1.We have rationally developed a benzo-BODIPY-based fluorescent probe MS5to detect Hg²⁺in a neutral aqueous solution.The probe is obtained in a higher yield by a substitution,condensation,and reduction reaction.Due to the photoelectron transfer?PET?process between the benzo-BODIPY fluorophore and the electron-donating nitrogen atom of the carboxy-thiol group,the probe MS5 has no fluorescence,and after the receptor is complexed with Hg²⁺,the PET process was blocked and the system showed strong orange fluorescence.The probe MS5 has high selectivity and high sensitivity toward Hg²⁺,and has a fast response,a unique detection limit?5.7 nM?,and can be detected with test strips.2.We designed and synthesized a novel rhodamine-like fluorescent probe MP for Hg²⁺/MeHg⁺detection.The probe MP has no fluorescence due to the spirolactam structure on rhodamine.In the presence of Hg²⁺/MeHg⁺,a mercury ion-catalyzed intramolecular desulfurization cyclization reaction occurs,and the spironolactone ring is opened,and the system emits strong orange fluorescence.The probe MP has the advantages of high selectivity,good sensitivity and rapid reaction,and can be used for real-time quantitative detection of Hg²⁺/MeHg⁺.3.We have rationally developed a novel,simple ICT-based benzocoumarin fluorescent probe MS6 for the detection of Hg²⁺.The probe can be obtained by a three-step reaction of protection,substitution,and sulfurization.In the presence of mercury ions,the thiocarbonyl group in MS6 first forms a relatively stable non-fluorescent complex with Hg²⁺through the S-Hg bond,and then desulfurizes the thiocarbonyl group by water to obtain benzocoumarin.The probe MS6 has the advantages of simple preparation,good water solubility,low detection limit and rapid response,and can be used for real-time quantitative detection of Hg²⁺.4.We designed and synthesized nine thiophene-coumarin compounds.The dyes are obtained by a two-step reaction of chloro-formaldehyde and condensation.Their UV absorption spectra and fluorescence emission spectra have been studied.The effects of solvent effects and substituent effects have been discussed.The experimental results show that the thiophene-coumarin dyes have the advantages of small molecular weight,simple synthesis steps,good solubility,high quantum yield and spectral control,which have potential biological application prospects.