Fluorescence Sensor Containing Fluorene And Amidoxime Conjugated Polymer Based On Uranyl Detection

Uranium is a key element of nuclear fission.As human demand for non-fossil energy continues to grow,the use of uranium continues to increase.However,uranium is not only radioactive and toxic,but also accumulates in organisms,and uranyl is easily soluble in aqueous solutions and will migrate in the environment.Therefore,even trace amounts of uranium will cause harm to the ecological environment and biological safety,so the detection of trace amounts of uranium is the most concerned issue.At present,many methods for monitoring uranyl ions have been developed,including atomic absorption spectroscopy,inductively coupled plasma mass spectrometry,ion chromatography and electrochemical methods.Despite the high sensitivity of these analytical methods,they require the use of expensive large machines,complex and stringent experimental conditions,and high operating costs.Compared with these methods,fluorescence is a simple,fast,highly selective and low-cost method for detecting metal ions.At present,the polymerization fluorescent sensor of uranyl ions has become a research hotspot.However,there are some shortcomings reported in the literature for uranyl polymerized fluorescent sensors,such as a high proportion of organic solvents in the detection system,a detection limit of less than nanomolar levels,a long response time,and the presence of many interfering ions.These factors affect the sensor detection of uranyl ions.Therefore,in this thesis,uranyl conjugated fluorescent polymers were prepared by functionalizing polyfluorene with amidoxime,and their fluorescence properties and mechanism for uranyl ions were discussed.The specific work content is as follows:1.It has introduced the working principle of the fluorescent conjugated polymer chemical sensor and summarize the application of the fluorescent conjugated polymer sensor in metal ions,anions,biomolecules and the research status of UO₂²⁺ion fluorescent conjugated chemical sensor.2.A fluorescent conjugated polymer sensor P2 containing amidoxime groups was designed and synthesized.The following studies were carried out:?1?The structure of the target product P2 was determined by FT-IR spectroscopy and ¹³C NMR.?2?Explore the effects of various conditions,such as the water content in the solvent,pH value,and action time on the fluorescence performance of the sensor P2 and UO₂²⁺,and found that the sensor can be applied in a higher water system,and at the same time,the optimal fluorescence response conditions of P2 to UO₂²⁺were obtained:pH=6.0,response time t=5 min,solvent V?N,N-dimethylacetamide?:V?water?=20:80.?3?Various cations(Zn²⁺,Mg²⁺,Dy³⁺,Eu³⁺,Ca²⁺,Cd²⁺,Zr⁴⁺,La³⁺,Sm³⁺,Th⁴⁺,Ag⁺,Co²⁺,Al³⁺,Mn²⁺,Cr³⁺,Fe³⁺,Ni²⁺,Hg²⁺,Pb²⁺,Ba²⁺,Na⁺,Cu²⁺,Bi²⁺,K⁺,Cs⁺,Nd³⁺,VO²⁺,Sr²⁺,and In⁺)affect the detection of UO₂²⁺by P2.The results show that the conjugated polymer fluorescence sensor has excellent selectivity for UO₂²⁺,especially the lanthanide and actinide metal ions do not interfere with it.?4?The fluorescence detection method of P2 to UO₂²⁺is established.The polymer sensor has a good linear relationship between uranyl ion concentration in the range of 10-200 nM?R²=0.9918?,and the detection limit can reach 7.4�10^-9 M.The detection method has been successfully applied to the detection of uranyl ions in actual water samples,and the sensor has certain advantages over the sensors reported in the literature.?5?The first-principle principle was used for simulation and hydrogen spectrum titration and infrared spectroscopy were used to further determine the action modes of P2 and UO₂²⁺,and the fluorescence quenching mechanism of UO₂²⁺and P2 was proposed.