New Fluorescent Sensing Materials For The Detection Of Micro-Trace Nitroaromatic Explosives

Explosives are closely related to human life,and have been applied to many areas of human life.Nitro-aromatic explosives are currently the most widely used materials due to their wide range of sources,easy to synthesized,and low cost,which makes them the main choices for many criminals.The threat of explosives to the safety of people's lives and property still gives us a deep alert.Therefore,the detection of explosives has always been a very popular and cutting-edge research topic in the world.Not only that,explosives could enter the soil and groundwater,which will seriously pollute our environment.People drink water containing nitroaromatic explosives will lead to a series of diseases like cancer,skin diseases and abnormal liver function.The detection of explosives is an urgent issue that demands immediate attention.Fluorescence sensing materials have been attracted wide attention because of their high sensitivity,easy to synthesis,and fast detection.The synthesis of fluorescent conjugated polymers enables the rapid and efficient detection of explosives.The molecular wire effect of fluorescent conjugated polymers can amplify the fluorescence detection signals and improve the detection sensitivity.In particular,hyper-branched conjugated polymers with alkyl chain not only increase the solubility but also the sensitivity of the explosive detection.The synthesis of fluorescent molecules with aggregation-inducing activity enables the detection of the presence of explosives in aqueous medium.In this paper,two kinds of fluorescent molecules were synthesized for the improvement of the quenching efficiency and detecting nitroaromatics in aqueous medium.The first system is a fluorescent compound with aggregation induced emission property;in order to increase the quenching efficiency and solubility of the conjugated polymers,we also synthesized a fluorescent sensing material with hyper-branched conjugated structure.Firstly,the synthesis of molecules with aggregation induced emission property.Unlike traditional fluorescent sensing materials,most of the traditional fluorescent materials are conjugated fluorescent polymers.Due to the increase of the solution concentration,the conjugated polymer will cause self-quench(ACQ),resulting in fluorescence quenching.The synthesize of aggregation induced emission compounds effectively solves the problem of self-quenching of the fluorescence due to high concentration leads to self-fluorescence quenching,and the aggregation induced emission molecules can achieve the detection of nitroaromatic explosives in aqueous medium.Two kinds of fluorescent molecules with aggregation induced emission properties were synthesized by using 2,2-Dimethyl-1,3-dioxane-4,6-dione and triphenylamine as start materials,and they were used for the detection of nitroaromatic explosives especially for picric acid.Experimental results showed that both of the two compounds were sensitive to picric acid(PA).It can be used as an excellent fluorescent sensing material in detecting explosives.Secondly,we also synthesized a conjugated fluorescent compound with two-dimensional hyper-branched structure,and synthesized a fluorescent sensing material with excellent sensing properties by using pyrazine and carbazole as raw materials.Solubility experiments showed that the two compounds have good solubility in many common organic solvents.Thermo-gravimetric experiments showed that the compounds had good thermal stability and can prolong the lifetime of the fluorescent materials.By examining its optical properties and the detection of picric acid,the compound has high sensitivity toward picric acid and can be used as promising fluorescent sensing material in detecting picric acid.