?-conjugated Materials Having The Same Thiophene And Malononitrile Skeleton For Detection Of Nitroaromatic Compounds

The detection of explosives has been a focus in research,not only causing the terrorist attacks in the international community,but also causing pollution in the environment and posing a potential threat to human life and property.Among a wide variety of explosives,nitroaromatic compounds?NACs?are applied widely,not only can be used in terrorist activities,blasting engineering and defense military operations,but also in the dye industry,pharmaceutical industry,and the chemistry lab.Residues of NACs in the environment would harm to human directly or indirectly.Therefore,the rapid detection of NACs has been widely concerned by researchers.Among those detection methods,fluorescence chemical sensors have been valued by scientists for its advantages such as low cost,high selectivity,easy operation,and convenient on-site detection.Fluorescent molecules with aggregation-induced emission?AIE?are very suitable for the detection of NACs as chemical sensors.The AIEgens have weak fluorescence in dilute solution,but emit strong fluorescence in the aggregated state.The interaction between electron-rich AIEgens and electron-deficient NACs leads to fluorescence quenching,thus achieving rapid detection through this sensitive response.In this dissertation,a series of thiophene/malononitrile derivatives with 2-?thiophene-2-ylmethylene?malononitrile?TMM?skeleton are designed based on the above contents,and characteristics of AIE also be studied for exploring its ability to recognize NACs in the environment.Firstly,taking TMM as the skeleton,different numbers of pyridine and tetraphenylethylene?TPE?were introduced and connected to different positions to obtain compounds D1,D3 and D4,finally realize a combination of restriction of intramolecular rotations and restriction of intramolecular vibration.Via UV-vis and fluorescence spectra,the three dyes synthesized have obvious AIE characteristics,and we use them to identify NACs in the aqueous phase.Fluorescence titration results showed that the compounds have potential sensing properties for picric acid?PA?.According to detection limits of compounds D1,D3 and D4 are 1.77?10^–3 M,8.97?10^–4 M,and 3.07?10^–4 M respectively,for PA detecting in the solutions.The test paper is prepared by self-assembly method,the visual detection limit of PA is 11.5 pg/cm² with the naked eye in the test strip.Also,the calculations of electrochemistry,theoretical energy gaps,and relative potential energy were comprehensively compared in this dissertation.The results show that TMM derivatives could provide important ideas for the fabrication and development of future fluorescent materials.