Nitroaromatic Compounds Based On Electronic Giving And Receiving The Detection Of Thin-film Fluorescence Sensor Design, Preparation, And Sensor Performance

Nitroaromatic compounds(NACs) are typical explosives and common organic contaminants which are a real threat to public security,terrible destroyers to environment and toxics to biological systems.Moreover,they are considered as potential carcinogens.So developing a sensitive sensor for detect trace amount of NACs has eminent significance for discovering hidden landmines,preventing terrorist attacks and monitoring environment qualities.Among NACs sensitive sensors reported in the documents,fluorescent conjugated polymer film sensors have gained the closest and the most extensive studies,due to its "molecular wire" or "wring molecular recognition sites in series" effect.These sensing films display high photo-stability and ultra-high sensitivity and it has been demonstrated to be effective sensor for the NACs in air.However,they also have unavoidable disadvantages,slow diffusion of analytes in the film system and leaching of the fluorophores,which make it hard to be used in solution systems.Therefore,developing novel fluorescent film sensors to avoid these problems is real in need.Our program in this dissertation was aimed to fabricate NACs sensitive fluorescent film sensors via chemically bonding the polycyclic aromatic on the glass plate in a SAMs way.Employing polycyclic aromatic as the sensing element is due to the donating and accepting interaction between the NACs and polycyctic aromatics,which will help the NACs close to the surface of the film and produce the fluorescent quenching of the film sensors.The SAMs technique to immobilize the fluorophores on the outmost layer of the SAMs-functional glass plate is an effective way to solve the leaching and diffusion problems.This is because a SAMs film displays high stability and sensing elements in these films can directly contact with analytes.Given the above consideration and the previous work in our group,a fluorescent film sensor for NACs vapors was designed in the first part of this dissertation.It was prepared by immobilizing the pyrene derivatives on the epoxide-terminated glass plate via long spacers in a SAMs way.As discovered in the study,the sensitivity of the film to the NACs analytes mainly depends on the vapor pressure of a given NAC and the quencher size.The detection limits to the common explosive vapors, 2,4,6-trinitrotoluene and 2,4-dinitrotoluene,are 7.14×10^-12 and 5.49×10^-11 g·mL^-1,respectively. Compared to the film with shorter spacers,this film shows slower response to NACs,but higher selectivity to the quencher sizes.In addition,the response of the film to NACs is barely influenced by the presence of some common chemical vapors,such as benzene,toluene,ethanol and perfume. Moreover,the detecting process of the film for NACs is reversible,which promises its potential for practical applications.In the second part of this dissertation,another fluorescent film sensor for the detection of NACs in aqueous phase has been developed via chemical immobilization of dansyl group on an epoxy-terminated self-assembled monolayer on glass plate.Thank to chemical attachment of the chromophore on the substrate,the present film shows a satisfying stability and avoids the problem of leaching of the chromophores.Increasing the length of the spacers results in a dramatic improvement in the performance of the film compared to those with similar structures.Fluorescence quenching experiments demonstrates that in aqueous medium,the emission of the film is more sensitive to nitrobenzene than to other NACs,including 2,4,6-trinitrotoluene,2,4-dinitrotoluene, p-chloronitrobenzene,m-dinitrobenzene,p-dinitrobenzene,and etc.This exceptional result has been rationalized by considering the possible hindrance effect induced by the compact conformation of the long flexible spacer.It is also demonstrated that the nitrobenzene quenching is static in nature,and the response of the film to nitrobenzene is fast and reversible.