Synthesis And Study On Ion Recognition Performance Of Coumarin Derivatives Fluorescent Probes

Heavy metal ions in the environment are one of the common toxic pollutants in life.Once water resources,soil resources and various organisms are polluted by heavy metal ions,they will have a serious impact on themselves.The pollution of heavy metal ions will affect the ecology,environmental balance and cause serious harm for human development.Thus,reasonable monitoring of the presence of heavy metal ions is urgent.Fluorescent probes have the advantages of low interference and convenient detection,so they are detected by metal ions.In this thesis,based on the design,synthesis and application of coumarin-based Schiff bases as the research content,five new coumarin-based Schiff base fluorescent probe compounds with different substituent groups have been successfully prepared and their metal ion recognition properties are studied.The specific research content is as follows:（1）A novel dual-functional fluorescent probe CTT based on coumarin and thiadiazole was synthesized.The probe CTT has excellent selectivity and specificity for Cu²⁺and it can be recognized Cu²⁺by the naked eye.Probe CTT can recognize Hg²⁺by fluorescence enhancement and has good selectivity and sensitivity for Hg²⁺.The binding mode of the probe CTT and Cu²⁺,Hg²⁺was further explored by ¹H NMR titration,mass spectrometry and the theoretical calculation.The results of DFT support the two proposed binding modes.The probe CTT detection of the Cu²⁺,Hg²⁺are also explored in practical applications and the experimental results show that the detection of Cu²⁺by the probe CTT can be used in the test strip experiment and the probe CTT can be used to detect Hg²⁺in actual water samples sensitively.（2）Two new fluorescent probes CIF and CI based on coumarin-indolyl were successfully designed and synthesized.A series of optical experiments,the exploration of the binding mechanism of identifying substances and the exploration of biological applications were carried out.The experimental results show that the fluorescent probe CIF has excellent selectivity and specificity for Cu²⁺and the fluorescence intensity of Cu²⁺is increased by nearly 20 times.The combination of CIF and Cu²⁺was determined by the results of Job’s curve,mass spectrometry,¹H NMR titration experiment and theoretical calculation.The probe CIF is less toxic to cells and the detection of Cu²⁺by the probe CIF can be well used in cell visualization.Probe CI can recognize Cu²⁺by fluorescence enhancement with good selectivity and sensitivity.The binding mode of probe CI and Cu²⁺was further explored by ¹H NMR titration and mass spectrometry.The theoretical calculation results of DFT support the proposed combination mode.In addition,cell imaging experiments show that the probes CIF and CI can perform imaging detection of Cu²⁺in He La cells,and the detection effect was very significant.（3）Two new fluorescent probes CBIF and CBI based on benzocoumarin-indolyl were designed and synthesized.The experimental results show that the probe CBIF has excellent selectivity and specificity for Cu²⁺.Probe CBIF After adding Cu²⁺,the probe CBIF solution has a color change that can be observed"with the naked eye".The binding mode of the probe CBIF and Cu²⁺was determined through the results of the Job’s curve,IR,¹H NMR titration experiments and theoretical calculations.Practical application experiments have proved that the probe CBIF can be used as a"test strip"to detect Cu²⁺ions.The probe CBI can recognize Cu²⁺with good selectivity through weakened UV-vis absorbance and fluorescence intensity enhanced.The binding mode of probe CBI and Cu²⁺can be further explored by ¹H NMR titration.The theoretical calculation results of DFT support the proposed combination model.In addition,the application experiments of actual water samples showed that the probe CBI could detect Cu²⁺in the environment very well and cell imaging experiments show that the probe CBIF and probe CBI can image Cu²⁺well in Hela cells,and the detection effect is very obvious.