Design And Synthesis Of Porphyrin Fluorescent Probe For Detection Of Trace Nitroaromatic Compounds

In consideration of social safety and environmental risk of picric acid,fast and selectively detection of nitro-aromatic explosives PA is vital important.In this work,combining with the density functional theory calculations,we design and synthesize the zinc porphyrin fluorescence probes bearing urea functional groups for the fluorescence detection of nitroaromatics.The results show that the zinc porphyrin ZH-1 bearing urea functional groups and one of its intermediates,aminoporphyrin ZH-3 can be fast and selectively detectionof picricacidwith significantlyfluorescencequenching.andother mononitroaromatics,dinitroaromaticscan not quench the zinc porphyrin ZH-1 and aminoporphyrin ZH-3 fluorescence.¹H-NMR titration of Zinc porphyrin ZH-1 and aminoporphyrin ZH-3 upon the addition of PA have confirmed the hydrogen bonding generated obvious between the urea functional group as well as amino group and the nitro group,resulting in a rapid fluorescence response.It was demonstrated that the hydrogen bonding strategy can be applied to fluorescent probe molecules designed for rapid and selective detection of picric acid.The structure of the porphyrin fluorescent probe was characterized by ¹H-NMR,¹³C-NMR and high resolution mass spectrometry?HRMS?.In this thesis,the main contents and results are summarized as follows:In Chapter 1,the progress of fluorescence quenching method and various sensing mechanisms for fluorescence based explosive detection are reviewed.The second chapter mainly focuses on the design and synthesis of zinc porphyrins bearing urea functional group.We first performed DFT calculations on porphyrin molecules andvariousnitrocompounds,andthenthe5-acetamidophenyl-10,15,20-triiodophenylporphyrins using the Lindesy method was synthesized,and amino porphyrin obtained via the hydrolysis of porphyrin bearing the amide groups.Furthermore,the reaction of isothiocyanate or isocyanate with aminoporphyrin was carried out.Six kinds of porphyrin derivatives were synthesized.And the corresponding structures was characterized by ¹H-NMR,¹³C-NMR and high resolution mass spectrometry?HRMS?.Meanwhile,the synthesized porphyrins were characterized by UV-Vis absorption spectra and fluorescence emission spectra.The third chapter is focus on detection of nitroaromatic compounds with porphyrin fluorescent probes.The fluorescence quenching experiments of synthetic porphyrin derivatives and various nitroaromatics were investigated.The results of fluorescence titration experiments showed that the zinc porphyrins ZH-1 and aminoporphyrin ZH-3 have significant detection effect on PA.From the fitting curve of the scatter plot of I₀/I vs[PA],the Stern-Volmer constants of ZH-1 and ZH-3 are 208 and 1167,respectively.From the plot of(I_max-I)/(I_max-I_min)vs.log[PA],the detection limits of ZH-1 and ZH-3 to PA were 221 ppb and363 ppb.The fluorescence quenching mechanism of the selective fluorescence detection of PA with zinc porphyrin ZH-1 and aminoporphyrin ZH-3 was investigated by nuclear magnetic titration,confirming that hydrogen bonding is the essential reason of fluorescence quenching.