Design,Synthesis And Properties Of Organic Fluorescent Probe For Hg²⁺ And OCl^- Based On Fluorescein

Owing to excellent selectivity,strong anti-interference ability,simple and easy handing,and good reproducibility,the organic fluorescent chemosensors have been widely applied to real-time monitoring of the environment pollutants and biomedical detection.Among the various fluorophore,fluorescein is one of the few non-toxic dyes with high fluorescence quantum yield and good biocompatibility,it has received extensive attention in fields such as bioimaging and environmental detection.At present,there are few reports of the probes based on fluorescein,and it is of great significance to further study the synthetic methods of this kind of probes.In this paper,based on fluorescein,we designed and synthesized the organic fluorescent probes,which could specifically recognize mercury ions and hypochlorite,its sensing performance and recognition mechanism also are studied.The main contents are as follows:1.Synthesis and application of probe for Hg²⁺based on thiooxofluorescein.Sulfur atom was firstly introduced into the fluorescein hydrazide with Lawesson reagent,the fluorescent probe FL was synthesized.Then FL reacted with acetaldehyde,2-Thiophenecarboxaldehyde,p-hydroxybenzaldehydeand N-methylpyrrole-2-carboxaldehyde via the Schiff base reaction,the resulting compounds FLSQ?FLS2?FLSH and FLSN,which could detect Hg²⁺with high selectivity and sensitivity.In further study,it was found that when FL used as probe to detect Hg²⁺,there are still some fluorescence interference of Cu²⁺.But after the introduction of aldehydes via the schiff base reaction,the probes of FLSQ,FLSH,FLS2 and FLSN could eliminate the fluorescence interference of Cu²⁺and realize the specific identification of Hg²⁺,and the detection limits were 1.28×10^-88 M?3.90×10^-8M?7.22×10^-88 M and 1.03×10^-77 M,respectively.What's more,cellular imaging experiment revealed that the sensor had excellent biocompatibility and low cytotoxicity that could be utilized for monitoring Hg²⁺in living cells.2.Synthesis and application of a water-soluble fluorescein derivative probe for Hg²⁺.A novel fluorescent probe FLHA was synthesized by a simple one-step reaction between fluorescein hydrazide and glyoxylic acid monohydrate.The fluorescent probe has excellent water solubility and can detect Hg²⁺in the solution containing 5%EtOH with high selectivity.Through further investigation,we learned that the sensing process is mainly as follows:Hg²⁺promoted hydrolysis of amide,in which Hg²⁺firstly formed a complex with FLHA,and then the ring-opened amide form of fluorescein was rapidly formed by hydrolysis reaction,leading the significant changes in color and fluorescence intensity of solution.What's more,the mechanism of complex promoted the hydrolysis reaction is different from the traditional recognition mechanism of Hg²⁺,which provides a new idea for designing the Hg²⁺fluorescence probe.3.Synthesis and application of ratiometric probe for hypochlorite based on fluorescein/coumarin.A fluorescence ratiometric probe FLNC containing double fluorophores was designed and synthesized,the two fluorophores were connected by diacylhydrazine.In further study,when OCl^-was added,the two fluorophores in the FLNC could have a rapid response simultaneously,with high selectivity and sensitivity towards OCl^-among other ROS/RNS and anions,and the detection limit was measured to be 3.0×10^-77 M.In addition,the color of the solution changed from yellow to orange when OCl^-was introduced,which could be observed by the naked eye and it has a short response time?completed within one minute?,which suggestes that the probe FLNC has the potential capacity to used in real-time detection...