The Synthesis And Properties Of Fluorescence Chemical Sensor Based On Tetrastyrene And Triphenylamine As Chromophore Abstract For Thorium Ions

The thorium element is a radioactive lanthanide metal found in the earth's crust with an average concentration of 10 mg/L.It is widely distributed in phosphates,silicates,carbonates and oxides and is three to four times more abundant than uranium.The thorium is used to produce nuclear fuel,so it ensures long-term sustainable development of nuclear energy in addition to its applications in industry and medicine;Hazardous waste is generated during the mining process,causing serious damage to the environment.Continued exposure of living organisms to thorium can lead to serious genetic defects and may lead to cancer;thorium compounds may also cause dermatitis and kidney damage due to their toxicity.The World Health Organization?WHO?provides a tolerance for thorium of 0.6 g/kg per day.Therefore,methods for qualitative and quantitative determination of Th⁴⁺ions are very important.At present,the techniques for detecting ruthenium are electrochemical methods-anodic stripping voltammetry,inductively coupled plasma method,atomic absorption method,etc.,for selective detection of toxic metal ions.These detection methods have excellent sensitivity,but the instruments are expensive and experimental.Strict requirements,complex sample preparation,and can't be applied to the detection and localization of Th⁴⁺ions in cells.The development of fluorescent chemical sensors has become an important alternative to traditional technology.Fluorescence chemical sensor method is regarded as one of the best methods for detecting ions because of its advantages of simple operation,good selectivity,high sensitivity,simple sample preparation and trace analysis.A number of fluorescent chemical sensors for detecting ions have been developed,but only a few fluorescent chemical sensors are used to detect Th⁴⁺ions,and ratiometric fluorescent for Th⁴⁺ions detection was not been reported.These above reported probes for the detection of Th⁴⁺ion depended only on the enhancement or weakening of the fluorescence intensity,which would be significantly affected by the instrument efficiency and environmental conditions such as variation of chemosensor concentration,background fluorescence,and photo bleaching.Compared with these sensors,ratiometric fluorescent sensor could provide a built-in calibration for the environment by recording two emissions ratio signals at different wavelengths,which could effectively provide sensitivity and improve measurement accuracy.Therefore,it is necessary to synthesize a ratiometric fluorescence chemical sensor that specifically recognizes Th⁴⁺ions and can be applied to cells,and such fluorescent chemical sensors should have high biological and medical research value.In Chapter 2,a ratio-based fluorescence chemical sensor with specific recognition for Th⁴⁺ion was synthesized based on tetrastyrene as chromophore and beta-dione structure recognition group.The performance of the fluorescence chemical sensor was studied,and a new method for detecting Th⁴⁺ion fluorescence was proposed.In the third chapter,a fluorescence-enhanced Th⁴⁺probe based on triphenylamine group was synthesized.The specific work is as follows:1.The fluorescence detection method,the relationship between the structure of fluorescent chemical sensor and fluorescence generation,the influence of external conditions on the fluorescence performance of chemical sensor,the fluorescence chemical sensor and its structure,the selection of fluorescent groups in the sensor,the research status of Th⁴⁺ion fluorescence chemical sensor,the purpose,significance and content of the experiment are introduced.2.A ratio Th⁴⁺ion fluorescence chemical sensor BH-TPE based on tetra-styrene as chromophore was synthesized from4-hydroxytetra-styrene-2-formaldehyde and malonyl hydrazide.Through the experiment of ultraviolet and fluorescence response of BH-TPE and Th⁴⁺ions,the following conclusions are drawn:in the solution of pH=2.0V?methanol?:V?water?=7:3,the probe shows 450nm fluorescence peak without adding Th⁴⁺.After adding Th⁴⁺,450nm peak disappears and a new fluorescence peak appears at 522nm.The fluorescence emission intensity of BH-TPE has a good linear relationship with the concentration of Th⁴⁺in the range of 0 to 10?M?R²=0.9724?,and the detection limit is2×10^-8 M.Besides copper ions,other metal ions do not interfere with the sensor BH-TPE in the range of Th⁴⁺concentration?R²=0.9724?.The coordination mechanism of sensor BH-TPE with Th⁴⁺ion was discussed by NMR titration,IR,MS and theoretical calculation?DFT?.The fluorescence mechanism of sensor BH-TPE responding to Th⁴⁺ion was proposed.The ESIPT process of probe was destroyed because the hydrogen bond of probe was destroyed in strong acidic environment.Thus,the emission of enol at 450 nm was shown.After adding Th⁴⁺ion,the fluorescence mechanism of sensor BH-TPE responding to Th⁴⁺ion was also proposed.The coordination of N and O atoms from the Schiff base of tetrastyrene enhances the fluorescence intensity by transferring-C=N-N lone pair electrons to the Th⁴⁺ion center.Coordination also improves the rigidity of the probe BH-TPE structure,making it more planar and conjugated,thus enhancing the fluorescence intensity,which is known as chelating fluorescence enhancement effect.Importantly,fluorescence chemical sensor BH-TPE can perform fluorescence imaging of HeLa cells in acidic system,and achieved good results.3.A Th⁴⁺ion fluorescence chemical sensor BH-TPA based on triphenylamine as chromophore was synthesized from triphenylamine derivatives and malonyl hydrazide.Through the ultraviolet and fluorescence response experiments of the sensor BH-TPA and Th⁴⁺ions,the following conclusions are drawn:in the solution of pH=2.0 V?DMF?:V?H₂O?=1:1.The fluorescence intensity of the probe showed a good linear relationship y=94.532x+890.43?R²=0.991?with the concentration of Th⁴⁺at 0-12?M.Fluorescence titration provides a simple and effective method for the detection of Th⁴⁺ions in unknown solutions.