Design,Synthesis And Properties Of Fluorescent Enhanced Organic Small Molecule Fluorescent Probes

In recent years,the fluorescent probe of organic small molecule is widely used in detecting heavy metal cations and anions pollutants,which are toxic and harmful to human and environment.There are many outstanding advantages,such as,simple structure,easy synthesis,high selectivity,high sensitivity and anti-interference ability,etc.In addition,the fluorescent probes of organic small molecules can also be used to realize fluorescence imaging in cells.However,it is not fit for the traditional methods on this advantage.In this paper,with the common detection mechanisms and fluorophores,a series of turn on organic small molecule fluorescent probes have been designed and synthesized to detect the toxic anion?CN^-?and cations(Ag⁺?Zn²⁺?Hg²⁺)in the aqueous solution.The main work of this paper focuses on the following aspects:1.Three kinds of simple small molecules M1,M2 and M3 have been designed and synthesized by Knoevenagel condensation reaction based on the 1,2,3,3-tetramethyl-3H-indol-1-ium iodide with 4-?diphenylamino?-benzaldehyde,2-phenyl-2H-1,2,3-triazole-4-carbaldehyde,quinoxaline-2-carbaldehyde.We found that only the probe M1 can be as fluorescence enhanced?"turn on"?small molecule fluorescent probe for the detection of CN^-in aqueous solution.Based on the nucleophilic addition reaction between the probe M1 and CN^-which block the ICT process of the M1 molecule,which is changed from the none fluorescence to strong blue fluorescence,the same times the color of the solution from purple to colorless.The detection limit of probe M1 for CN^-was 6.1×10-7 M.In addition,the probe M1 detecting CN^-was also studied in different water samples,which further showed that the probe M1 could be applied to the detection of CN^-in real water environment system.2.We have successfully synthesized a simple Schiff base M4 by using 4-?diphenylamino?-benzaldehyde and 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol.Which is fluorescence enhanced organic small molecule fluorescent probe.First of all,the probe M4 showed very good fluorescence response to Ag⁺ in the DMSO solution.The detection limit of probe M4 for Ag⁺ was 2.7×10-7 M.Secondly,in the mixed solvent EtOH-H2O?1:1 v/v,HEPES,50 mmol,pH=7.4?,the probe M4 showed a very good fluorescence response to the detection of Ag⁺,and has a high sensitivity and good anti-interference ability.The detection limit of probe M4 for Ag⁺ was 7.5×10-7 M.Finally,in the mixed solvent EtOH-H2O?1:1 v/v,tris-HCl,50 mmol,pH = 7.0?,the probe M4 showed a very good fluorescence response to the detection of Zn²⁺.The detection limit of probe M4 for Zn²⁺ was 2.35×10-7 M.More importantly,it also can be used to detect Ag⁺ and Zn²⁺ in living cells?Hela?by fluorescence imaging.3.Fluorescence enhanced organic small molecule fluorescent probe M5 for Hg²⁺ based on the Rhodamine B structure was designed and synthesized,which can detect Hg²⁺ by colorimetric and fluorescence dual channel.In the mixed solvent EtOH-H2O?1:1 v/v,HEPES = 50 mM,pH = 7.0?,the detection of Hg²⁺ has high sensitivity and good anti-interference ability.The detection limit of probe M5 for Hg²⁺ was 1.73× 10-8 M.In addition,the probe M5 detecting Hg²⁺ was also studied in different water samples,which further showed that the probe M5 could be applied to the detection of Hg²⁺ in real water environment system.