Synthesis And Application Of Nitro Activated Hydrogen Sulfide Fluorescent Probe

Hydrogen sulfide（H₂S）,as one of the simplest compounds in organisms,plays an important role in maintaining cell stability and normal life activities.Therefore,real-time detection and monitoring of H₂S in organisms is of great significance for in-depth understanding of the physiological and pathological role of hydrogen sulfide.Fluorescent probe method has become an important H₂S detection method because of its good selectivity and strong cell compatibility.At present,most of the known H₂S fluorescent probes have their own shortcomings,especially the detection speed of H₂S is slow.In view of the long response time of hydrogen sulfide fluorescent probe,we hope to improve the response speed of the probe by modifying the probe recognition group.Nitro（-NO₂）is a very important electron absorbing group in organic chemistry.The introduction of nitro into hydrogen sulfide recognition group can reduce the electron cloud density of reaction sites and accelerate the nucleophilic attack of hydrogen sulfide;At the same time,the introduction of nitro will also improve the leaving ability of the leaving group and accelerate its leaving,so as to improve the sensitivity of the probe.Based on this,this paper will focus on the construction of H₂S fluorescence recognition sites containing nitro,and use this to construct H₂S fluorescence probes to realize the rapid detection of H₂S.The research work of this paper mainly includes the following aspects:1.We constructed a fast response H₂S reaction site by introducing nitro in the ortho position of formyl group,and constructed a new fluorescent probe DPA-CHO for rapid detection of H₂S with dicyanoisofluorone as the fluorescent parent.Due to the introduction of nitro,the speed of nucleophilic addition reaction between H₂S and aldehyde group is improved,and then the existence of nitro also accelerates the nucleophilic addition speed in the molecule,so as to break the ester bond faster,rapidly enhance the fluorescence intensity（the fluorescence value increases rapidly to 1500within 2 minutes,and finally reaches stability after 15 minutes）,and greatly shorten the response time.The introduction of nitro group improved the response speed of the probe,but did not reduce the selectivity of the probe.Thiols and other sulfhydryl containing analogues did not interfere with the detection of H₂S by the probe.In addition,the probe has low cytotoxicity and good cell compatibility.Based on the above properties of the probe,we successfully applied the probe to live cell detection and imaging.2.Inspired by the above probes,nitro group was introduced into the adjacent position of azide group as the rapid response hydrogen sulfide reaction site,and the fluorescent probe DPA-N₃ for rapid detection of H₂S was synthesized.After the probe reacts with H₂S,the fluorescence intensity reaches about 50 times,and the response time is greatly shortened.In addition,the probe can specifically recognize H₂S and can be applied to live cell detection and imaging.3.A novel H₂S detection fluorescent probe 3 based on thiocarbonyl was constructed by introducing nitro into the aromatic ring.The introduction of nitro accelerates the response speed of the probe,and shows the advantages of good selectivity and low cytotoxicity.This probe can achieve the goal of rapid detection of H₂S in living cells.The construction of nitro containing H₂S recognition sites and the successful construction and application of probes DPA-CHO,DPA-N₃ and 3 show that introducing nitro into H₂S recognition sites to construct new rapid corresponding hydrogen sulfide fluorescence probes is an important and effective way.This method and the new hydrogen sulfide fluorescent probe have very important biomedical application value.