Preparation Of A Functionalized Glass Sensor And Its Sensing Performances For Nitroaromatics

Recently,the explosives threaten people's lives and property safety,so researchers draw more and more attention on explosives detection.As we all know,TNT(2,4,6-trinitrotoluene)and DNT(2,4-dinitrotoluene)are the main components of explosives.So,as long as we detected nitroarene,we will be able to achieve rapid detection of explosives.Since this nitroaromatics contain these strong electrons withdrawing group-a nitro group,which decreases the electron density of the phenyl ring.While the fluorescent conjugated polymers with the strong light trapping ability can produce an optical response-quenching,that the electron transfer from the fluorescent materials to nitroaromatics.Moreover,as a result of the ?-? conjugated structure the electrons can flow throughout the molecular chain,which can amplify the signal generated in response to the sensor and makes the detection of nitroaromatics possible.The graft of the polymer on the glass can effectively avoid leakage loss caused by spin coating,reduce ?-? chains accumulation and promote analyte permeation in monomolecular films.(1)A novel fluorescent conjugated polymer P was obtained by HECK reaction between fluorene with divinylbenzene,and then polymer P was grafted to the glass surface by appropriate reaction conditions,which was the rapid and sensitive explosives detector GS-P.The detector is designed on the basis of previous studies of small molecules grafted on glass surface,and combined the advantages of signal amplification,no leakage,the advantages of easy penetration.Regular changes in contact angles,the distribution of elements on glass surface and the fluorescence spectra of soaking residual polymer P both indicated the success in the grafting reaction onto glass surface.The AFM image from the microscopic point of view explained that the difference of the roughness leads to the different on quenching sensitivity.The bigger roughness for functionalized glass slide GS-P may be owing to the polymer was upright or inclined on the glass surface.The testing of nitro-aromatics show that the monolayers sensor in saturated vapor DNT,100 seconds quenched by 80%,while the spin-coated films I and? only quenched by 37%and 48%,indicating that the single monolayers sensor had high sensitivity and fast response characteristics.Finally,a series of tests about GS-P show the film has the advantages of good selectivity,high stability and repeatability.(2)In order to compare various types of fluorescent material response to nitroaromatics,this work designed a series of small molecule derivatives upon carbazole and fluorine.Through comparative study of carbazole ring,fluorene ring,double,triple and the withdrawing group,the results indicated different groups play a great role in the fluorescence performance.The experiments response to DNT showed that c and h had excellent performance quenched by 98%and the quenching mechanism is not a single but dynamic and static quenching co-existing.With regard to fluorescence lifetime,the fluorescence lifetime greater,the sensitivity for the fluorescent material response to DNT is higher.However,for i and b,the quenching rate is not very high,which indicated the fluorescence lifetime is not the only measure to sensitivity.From the point of view of calculated energy levels,the error may be related to sensitivity test results or outcome of the calculation or self-quenching.It is still needed for more in-depth study to further research the impact of fluorescent material HOMO energy level and the LUMO level of nitro aromatic molecules on the quenching rate.