Preparation And Properties Of Fluorescent Probes With Triazolyl Schiff Base

As we all know,metal elements were very common in our daily life.Trace elements were an integral part of the human body,and some metal elements could cause great harm to the human body,of which Al³⁺and Hg²⁺account for a large part.Excessive intake of aluminum is harmful to the human body.Aluminum was an amphoteric element.The compounds formed after the reaction were easily absorbed by the intestine and could enter the brain,affecting children’s intellectual development,and might cause senile dementia.When mercury exceeds the standard,it could cause ataxia,speech disorders,numbness of the limbs,paralysis of the limbs,and even death due to general paralysis.Therefore,it was very important to use a convenient and fast method to detected these metal ions.Fluorescent probes had mumerous advantages such as high sensitivity,good selectivity,convenient use,and no interference from external electromagnetic fields,so they has a wide range of applications in the fields of molecular biology,biochemistry,and medicine.In this paper,four types of fluorescent probes were designed and synthesized,one of which was for detecting Al³⁺and the other three were for detecting Hg²⁺.The main research contents are as follows:（1）A new fluorescent probe,Tri-Flu,was obtained by reacting 1,2,4-triazole and fluorescein,and the probe was characterized and tested by FTIR,¹H NMR,UV-Vis and fluorescence spectrum.The test results show that compared with other metal ions measured,the probe can specifically recognize Al³⁺with a detection limit of1.15×10^-8M.By measuring the Job’s curve,the binding ratio to Al³⁺was determined to be 1:1.Al³⁺can also be identified by naked eyes.In a solution with a concentration of10^-5M,the color of the solution changes from colorless to pink after combining with Al³⁺.And the corresponding orbital electron distribution and molecular geometric configuration of the compound were predicted by density functional theory（DFT）.The possible complexation mechanism of Tri-Flu for Al³⁺was inferred.（2）A new fluorescent probe,Tri-R6G,was obtained by reacting 1,2,4-triazole and rhodamine 6G,which can detect Hg²⁺based on the photoelectron transfer mechanism（PET）.The corresponding orbital electron distribution and molecular geometric configuration of the compound were predicted by density functional theory（DFT）.The probes were characterized by FTIR,¹H NMR,UV-Vis and fluorescence spectra.The test results show that compared with other metal ions measured,the probe can complex Hg²⁺1:1,and the detection limit is 1.61×10^-8 M.In addition,when Hg²⁺is recognized,the solution is at a concentration of 10^-5 M Medium,the color changed from colorless to pink,and can be applied to test paper,the color change is consistent with that in solution.（3）A novel photoelectron transfer（PET）fluorescent probe CH₃-R6G was synthesized from methyl triazole and rhodamine 6G matrix.Their structures were characterized,and their optical properties were studied by UV-vis and FL.The test results show that the sensitivity and selectivity of this probe to Hg²⁺are better than other various metal ions.Plotted by the standard curve,the detection limit is 1.34×10^-8 M.By plotting the Job’s curve,it was determined that the probe was bound to Hg²⁺1:1.In addition,the probe can also recognize Hg²⁺with the naked eye.After complexing with Hg²⁺,the color of the probe changes from colorless to pink.The orbital electron distribution and molecular geometric configuration of the compounds were predicted by density functional theory（DFT）.The probe CH₃-R6G was successfully applied to the imaging of Hg²⁺in living breast cancer cells,indicating its great potential for micro-detection of Hg²⁺in vivo.（4）A new type of photoelectron transfer（PET）fluorescent probe CN-R6G was synthesized from cyan triazole and rhodamine 6G matrix.The UV-visible absorption spectrophotometer and fluorescence spectrophotometer were used to study their optical properties.The test results show that the probe has specific recognition for Hg²⁺.The standard detection limit is 1.56×10^-8M,and according to the Job’s curve,CN-R6G and Hg²⁺are measured as 1:1 complex.And after complexing with Hg²⁺,the color of the probe changed from colorless to pink,which created a good condition for the naked eye to recognize Hg²⁺.The orbital electron distribution and molecular geometric configuration of the compounds were also predicted using density functional theory（DFT）.In addition,the probe CN-R6G was successfully applied to the imaging of Hg²⁺in living breast cancer cells,indicating its great potential for micro-detection of Hg²⁺in vivo.