Synthesis And Properties Of H₂S Fluorescent Probes Based On 2,4-Dinitrobenzenesulfonyl Identification Group

Hydrogen sulfide（H₂S）,the third gas-signaling molecule discovered after nitric oxide（NO）and carbon monoxide（CO）,is widely present in mammals and has important cytoprotective effects.Studies have also shown that H₂S is involved in many physiological and pathological processes,such as regulating inflammation,relaxing blood vessels,regulating blood pressure,etc.However,abnormal indices of H₂S can exhibit acute and highly toxic,leading to various diseases in humans.For example,low concentrations of H₂S have harmful effects on the visual system,respiratory system,and central nervous system.High concentrations of H₂S can lead to a variety of diseases such as high blood pressure,Alzheimer’s disease,Parkinson’s disease.Moreover,H₂S is also a sulfur-containing bacterial metabolite in raw food and is considered to be one of the prominent volatiles in the spoilage process of raw foods.Food spoilage can lead to excessive concentrations of H₂S residues,which can adversely affect human health.In addition,H₂S is widely exist in industrial wastewater,and H₂S can transmit to the environment and the human body through ecological flows and the food chain,causing negative effects.The existence of H₂S is closely related to the natural environment,human health,and human life.Therefore,it is of great significance to establish H₂S detection methods with high selectivity and wonderful sensitivity.Due to the advantages of low cost,simple structure,easy modification,excellent selectivity,rapid response,non-invasive analysis,high spatial resolution and real-time imaging,small molecule fluorescent probes have been widely used for molecular identification.In view of these research backgrounds,three novel H₂S fluorescent probes were designed and synthesized based on the H₂S recognition unit 2,4-dinitrobenzenesulfonyl in this paper.Their absorption spectra,emission spectra,selective identification,time-dependent and pH response in the corresponding solvents were systematically studied,and their application prospects were explored in test strips,environments,food and living cells.The main contents of the paper are as follows:The first chapter reviewed the research background,definition,composition,recognition mechanism of H₂S fluorescent probes,progress in the study of H₂S fluorescent probes with different reaction types and different fluorescent moieties and the application in various aspects,and putted forward the main research content of this topic on this basis.In the second chapter,the probe BDS-DNBS was synthesized using benzothiazole as the fluorescent group and 2,4-dinitrobenzenesulfonyl as the group for identifying H₂S.By exploring the optical response of BDS-DNBS to H₂S,it could be proved that BDS-DNBS was able to detect H₂S qualitatively and quantitatively.BDS-DNBS could identify H₂S by changes in ultraviolet absorption and fluorescence emission,and it showed a good linear relationship between H₂S concentration and fluorescence intensity in the range of 25-70μM.BDS-DNBS had potential applications in the environment,food and living cells.In the third chapter,the DAD-DNBS probe was synthesized basing on the thiophene-benzothiadiazole-thiophene（D-A-D）conjugated structure as a fluorophore and 2,4-dinitrobenzenesulfonyl as a identify group.In addition,the optical performance response,selectivity and anti-interference performance of DAD-DNBS detection of H₂S were explored.The results showed that DAD-DNBS could specifically recognized H₂S with an emission wavelength of 652 nm in the near infrared region,with a significant increase in fluorescence signal intensity and a two-fold increase in quantum yield before and after reaction with H₂S.In addition,the probe DAD-DNBS had promising applications,including testing H₂S in environmental water samples,tracking H₂S in foodstuff,test strip detection,and imaging of endogenous and exogenous H₂S in living cells.In the fourth chapter,the probe TPB-DNBS was synthesized by linking triphenylamine to the styrylpyridinium skeleton,then performing a salting reaction,and using 2,4-dinitrobenzenesulfonyl as the identification group.After a series of optical performance investigations,it was found that TPB-DNBS performed quickly reaction time,excellent selectivity and excellent sensitivity for monitoring H₂S.There was a distinct peak of fluorescence signal at the emission wavelength of 623 nm when TPB-DNBS treated with H₂S.In addition,the fluorescence color of the solution changed from no emission to orange and the response time was complete within 3 min.Moreover,it was confirmed through the application studies that TPB-DNBS had promising applications in targeting cell organelles,environmental detection,food quality tracking,and living cell imaging.