The Preparation And Properties Of TNT/TNP Bi-Functional Fluorescence Sensor

In recent years,fluorescence sensing technology has been widely focused based on the preparation of simple,portable,low cost,high sensitivity and selectivity and other advantages by the researchers.Based on the research status of fluorescent molecular probes in the detection of nitro-based explosives,two novel Schiff base small molecule fluorescent probes have been designed and synthesized for the detection of nitro-explosive.The selectivity and sensitivity of the probe to the nitro explosive were studied by UV-Vis absorption spectra and fluorescence spectra.The mechanism of the recognition of the probe molecules was analyzed by density functional theory.The main conclusions are as follows:(1)The novel Schiff base fluorescent probe S1 was synthesized and its single crystal was synthesized.The structure of probe S1 was identified by IR,NMR,MS,elemental analysis and so on.The photophysical properties of probe S1 were studied by UV absorption and fluorescence spectra,respectively.The results showed that the strong emission quenching at 412 nm and a new emission band at 530 nm was observed upon addition of TNT and TNP,respectively,showing excellent difference selectivity.Through the competition experiments of TNT and TNP,it is shown that the probe S1 is almost unaffected for the detection of TNT and TNP,even with the coexistence of other nitro-explosive molecules,which shows strong anti-interference ability.Fluorescence quantitative test results show that the detection limits of TNT and TNP in DMF buffer solution were 14.9 nM and 5.3 nM,respectively.The shortest distance between TNP and S1 is 2.2884 ?,which is less than the shortest distance between TNT and S1(2.3675 ?)by density functional theory(DFT)analysis.In addition,the HOMO/LUMO data show that the HOMO/LUMO energy difference of S1+TNP is 2.18 eV and that of S1+TNT is 2.62 eV,which indicates that the binding capacity of probe S1 to TNP is much larger than that of TNT.(2)Based on the defect that the detection sensitivity of probe S1 is not high,a new Schiff base fluorescent probe S2 was synthesized,and the structure of probe S2 was identified by IR and NMR.Through the qualitative test of UV-vis absorption and fluorescence spectra,it is shown that probe S2 also has excellent selectivity for TNT and TNP.Fluorescence spectroscopy experiments show that the probe S2 is not affected for the detection of TNT and TNP,even with the coexistence of other nitro-explosive molecules,showing a strong sensitivity.The detection limits of TNT and TNP in DMF buffer solution were 3.8 nM and 0.168 nM,respectively,which indicated that probe S2 had higher detection sensitivity comparing with probe S1.