Investigation Of Molecular Probes For Phosgene

Phosgene is a highly toxic gas,which is the most representative of asphyxiating poisons,widely used in industrial production to make it easily accessible,and thus pose a potentially serious threat to human health and the public security of all countries.Therefore,the development of rapid,sensitive and selective detection methods that response to phosgene is of great significance.In recent years,optical molecular sensors have developed at a faster rate,and it applicable range has become more and more wider.In this paper,we used heptamethine cyanine and naphthalimide as chromophores and fluorophores to design three molecular probes for phosgene based on different chemical mechanisms.The paper consists of four chapter,which are summarized as follows:The first chapter is an introduction,mainly expounding the basic concepts and common design principles of optical molecular sensors.And the development prospects of phosgene molecular sensors are summarized.Finally,the research work of this paper was proposed.In the second chapter,using 2-aminobenzylamine as a phosgene reaction site,we successfully designed and synthesized a heptamethine cyanine probe,which can efficiently and rapidly identify phosgene.Due to the strong bis-acylation reaction of phosgene,the two amino groups in the probe molecule can undergo intramolecular cyclization reactions with phosgene to form cyclic urea derivatives;and this causes great changes in absorption and fluorescence spectra(>100 nm),achieving phosgene colorimetric and fluorescence recognition detection.Therefore,a phosgene detection method based on cyanine dyes was established.Attaching the probe molecules to the paper strip allows the detection gaseous phosgene by the human eye.The sensing molecule showed specific and fast response to phosgene,and has high sensitivity(13 nM).In the third chapter,keto-type heptamethine cyanine was successfully used as an absorption/fluorescence probe for phosgene,based on the great differences in absorption and fluorescence spectra between keto-type and enol ester cyanine.The reactive phosgene can turn the carbonyl group into an enol ester group at the cyanine chromophore,which causes great redshift of absorption and fluorescence spectra(>100 nm),and thus enable the detection of pand hosgene.The sensor molecule responds quickly to phosgene with high sensitivity,has good selectivity to phosgene.In the last chapter,by Beckmann rearrangement,the naphthalimide was successfully designed as a molecular probe for phosgene.By means of phosgene-induced Beckmann rearrangement of turning ketoximes into acetamido-substituted naphthalimide derivative,a method for specific recognition of phosgene was developed.