Preparation Of New Fluorescent Sensor And Detection Of Sulfide

The fluorescence analysis method is a method for qualitative analysis and quantitative detection of the analyte due to the change of the luminescence characteristics of the fluorescence sensor after the interaction between the fluorescence sensor and the analyte.Over the years,fluorescence analysis has been widely used in the field of ion analysis due to its high selectivity,high sensitivity and simple operation.In this thesis,two kinds of fluorescent sensors were synthesized through rational design.The structure of the target sensor was characterized by ¹H NMR,FT-IR,PXRD and high-resolution mass spectrometry,and the synthesis and sensing mechanism of the target sensor were confirmed.The specific work is as follows:（1）In order to detect bisulfite ions in environmental samples and food,this thesis uses2-bromo-4-fluorobenzaldehyde as the skeleton,and is modified by indole group and morpholine group to prepare a 1,4 Michael additive fluorescence sensor for the determination of bisulfite ions in environmental samples and actual food samples.The experimental results show that the fluorescence performance of the morpholine indole-based fluorescence quenching probe is stable in the p H range of 4-10,indicating that the sensor has good resistance to environmental interference;time-dependent fluorescence titration experiments show that hydrogen sulfite The fluorescence quenching time of the sensor was 7 minutes,and the response speed was fast;the concentration-dependent fluorescence titration experiment showed that the sensor had good sensitivity to bisulfite ions,and the minimum detection limit was 0.039μM;competitive fluorescence titration Experiments show that the sensor has a high degree of selectivity for bisulfite ions;it is confirmed that the sensing mechanism of the sensor is 1,4 Michael addition by nuclear magnetic resonance detector and high-resolution mass spectrometry.In addition,the morpholine indole-based fluorescence quenching probe can be used for the visual detection of bisulfite ions,and the detection of bisulfite ions in food（white sugar and brown sugar）,with a recovery rate of（99.08-108.57%）.（2）In order to detect hydrogen sulfide in water samples,this thesis uses stable Ui O-66-NH₂as the main body and 4-azido-1,8-naphthalenedicarboxylic anhydride as the modified molecule to modify MOF by functionalization.A Ui O-66 functionalized fluorescent sensor based on the conversion of azide group to amino group was prepared for the determination of hydrogen sulfide concentrationinwatersamples.Thefunctionalmodificationof4-azido-1,8-naphthalenedicarboxylic anhydride into the structure of Ui O-66-NH₂can well inhibit the aggregation of 4-azido-1,8-naphthalenedicarboxylic anhydride molecules,and further Attenuate its aggregation-induced quenching effect.The experimental results show that:the time-dependent fluorescence titration experiment shows that the hydrogen sulfide turns on the fluorescence of the sensor for 40 minutes,but the fluorescence intensity increases nearly 10 times at 15 minutes,and the response speed is faster;the concentration-dependent fluorescence titration experiment shows that the sensor is sensitive to Hydrogen sulfide has good sensitivity,the lowest detection limit is 0.033μM;competitive fluorescence titration experiments show that the sensor has high selectivity for hydrogen sulfide;the sensing mechanism of the sensor is studied by infrared spectroscopy:reduction of azide group to amino group;Through scanning electron microscope characterization analysis,the morphology of the sensor before and after the reaction hardly changes,which further verifies the structural stability of the sensor in the aqueous environment.The above conclusions show that the fluorescence sensor has great potential for the detection and research of hydrogen sulfide in environmental samples.