Synthesis And Sensing Ability Of Novel Water-soluble Fluorescent Probes

The growing development of fluorescent probe is of great significance to the fields of environmental monitoring and biological detection.Recently,a series of fluorescent probes have been exploited to detect heavy metal cations(Cu²⁺,Pb²⁺,Zn²⁺),anions（HSO₃^-,ClO^-,CN^-）and various small molecules（H₂O₂,GSH,Cys）.Although fluorescent probes have the advantages of good selectivity,easy operation,and low cost,how to improve the sensitivity,selectivity,and water solubility of the probes still remains challenge.Herein,three organic fluorescent probes with low detection limits,specific selection and good water solubility were designed and synthesized in this dissertation,and their sensing performance were scrutinized.The representative contents are as follows:（1）Design and synthesis of the water-soluble fluorescent probe BPIS containing hemicyanine and its sensing performance towards Cu²⁺and HSO₃^-.At first,the probe BPIS was synthesized by Knoevenagel condensation reaction by using2,3,3-trimethyl-1-（3-sulfopropyl）-3H-indole-1-ammonium-5-sulfonic acid potassium and 4-（bis（pyridin-2-ylmethyl））Amino)benzaldehyde as the raw material.The molecular structure of the probe BPIS was characterized by ¹H NMR,¹³C NMR and MALDI-TOF mass spectrometry,and the detection performance of the probe BPIS towards Cu²⁺and HSO₃^-were studied by absorption and emission spectroscopy.There is a good linear relationship between the absorption intensity/fluorescence intensity of BPIS and the concentration of Cu²⁺and HSO₃^-.The minimum detection limits of BPIS for Cu²⁺and HSO₃^-are 4.02 n M and 3.47 n M,respectively.In addition,the probe BPIS can quickly monitor Cu²⁺and HSO₃^-in real water and sugars,demonstrating the application pof BPIS in environmental and food analysis.（2）Preparation of the water-soluble fluorescent probe HCyN based on hemicyanine-naphthalene and its sensing performance towards HSO₃^-.The probe HCyN was synthesized by Knoevenagel condensation reaction by using1-（carboxymethyl）-2,3,3-trimethyl-3H-indole-1-ammonium-5-sulfonic acid potassium and naphthalene derivatives as the raw materials.The molecular structure of the probe HCyN was characterized by ¹H NMR,¹³C NMR and MALDI-TOF mass spectrometry.When HSO₃^-was added dropwise to the HCyN solution,the UV absorption intensity of the probe at 463 nm gradually decreased,while the absorption at 305 nm increased,and the color of the solution changed from orange to light pink simultaneously.The fluorescence intensity of the probe is linearly related to HSO₃^-in the range of 0-1.0 eq,and the lowest detection limit is determined to be 10.4 n M.The detection menchanism is verified to be a 1:1 nucleophilic addition reaction.We have also successfully loaded the probe HCyN onto test paper,which can be used as a portable tool for HSO₃^-detection.（3）Synthesis of the fluorescent probe MZj-containing triarylimidazole and its ClO^–sensing performance.At first,the probe MZj was prepared by aldoamine condensation reaction between 4-（4,5-diphenyl-1H-imidazol-2-yl）benzaldehyde and2,3-diamino-2-butenedionitrile.The molecular structure of the probe MZj was verified by ¹H NMR,¹³C NMR and MALDI-TOF mass spectrometry.The probe MZj has the advantages of specific selection,good sensitivity,fast response and low detection limit.The detection limit is estimated to be 18.46 n M.The detection mechanism was substantiated to be HClO-promoted oxidative cleavage of olefinic C=C double bond.In addition,the successful fabrication of MZj-loaded test paper can be used as a portable tool to detect ClO^–.