Study on Phosgene Fluorescent Probes and Its Sensing Mechanism

Author:Xia Hong Cheng

Supervisor:song qin hua


Degree Year:2019





Phosgene is a highly toxic and widely used chemical compound.Phosgene has become a serious threat to humankind and public security because of its potential use by terrorists and unexpected release during industrial accidents.Therefore,it is particularly urgent to develop a simple,rapid and selective method for the detection of phosgene.Fluorescent probes work as a cheap,convenient and sensitive method for the detection of active compounds in the past years.However,there are only few reported fluorescent probes for selective detection of phosgene.For this reason,our work focuses on the design,synthesis and application of fluorescent probes for selective detection of phosgene.In the first part,inspired by the reaction site of o-phenylenediamine reported by Yoon group,we designed and synthesized o-phenylenediamine type probe,o-Pac,which was based on coumarin as fluorophore and o-phenylenediamine as reaction site.The probe o-Pac was used for the first time in the selective detection of phosgene,which made up for the selective test that was not done in Yoon’s work.The probe was used for selectively distinguish phosgene from other active acyl chloride compounds for the first time.And we verified the mechanism of photoinduced electron transfer(PET)process.On this basis,the detection paper was successfully prepared.The test paper contained the probe o-Pac can be conveniently used for the fast detection of phosgene gas in low concentration.Because the short absorption and emission wavelength of fluorophore coumarin,in the second part of the work,we connected the reaction site of o-phenylenediamine with the fluorophore BODIPY to form probe o-Pab.The absorption and emission wavelength of probe o-Pab was increased to realize the purpose of colorimetric detection of phosgene.The colorimetric detection of phosgene can be realized directly by naked eyes.The active reaction site of o-phenylenediamine can react with nitric oxide,we achieved the purpose of selective discrimination of nitric oxide by colorimetric and fluorescence changes in acetonitrile and chloroform solutions.Similarly,the test paper loaded with o-Pab can be used for selective detection of phosgene under naked eye.The color change and the emission of green fluorescence can be observed under naked eye visibility and portable ultraviolet lamp irradiation,respectively.In the third part,we found a new Boekelhide-like reaction,which was based on the reaction of phosgene and 2-alkyl substituted pyridine or quinoline nitrogen oxides in one step to form 2-chloromethyl substituted pyridine or quinoline under mild conditions.Chlorination of 2-substituted methyl by one-step reaction.And we have made a detailed study of the reaction mechanism.One of the substrates 2-methyl-7-methoxyquinoline nitrogen oxide(MQO)emmit obvious blue fluorescence after the reaction with phosgene,so it can be used as a fluorescence probe for the detection of phosgene.The probe MQO has the advantages of fast response,sensitive reaction,low detection limit and good selectivity.We also prepared a probe-contained MQO test paper for selective detection of low concentration phosgene gas.