Design,synthesis And Performance Study Of Ratio Fluorescent Probe For Detecting Hydrazine Hydrate And Bisulfite

Small molecule fluorescent probes have the characteristics of simple synthesis,low cost,strong selectivity,non-invasive visualization,and sensitive response.With a good combination of fluorescence imaging technology,they give full play to the excellent temporal and spatial resolution capabilities for the detection of biologically active molecules,it is widely used in the field of biomedicine.The quantitative detection of specific analytes by small molecule fluorescent probes is essential for various applications from life sciences to environmental monitoring.In recent years,it has become an excellent detection tool.Therefore,this thesis designed and synthesized two small molecule fluorescent probes to detect various chemical analytes,studied the detection mechanism of the probes,and carried out applications in cell imaging.Hydrazine hydrate（NH₂NH₂）is a strong reducing agent and antioxidant,widely used in various fields of industry,but its highly toxic nature will directly pollute the environment and seriously damage the human central nervous system and various human organs.Therefore,the development of a fluorescent probe that specifically detects hydrazine hydrate is of great significance to human production and life.In the second chapter of this article,we designed and synthesized the probe 3HF-HYD with the structure of 3-hydroxyflavone as the fluorescent molecular skeleton,which emits blue-green fluorescence（λem=501nm）under the excitation of ultraviolet light.Under the action of hydrazine hydrate,it passes through in the reaction sequence of substitution-cyclization-elimination,the ester group of probe 3HF-HYD is disconnected and the hydroxyl group is exposed,and then the ESIPT effect is turned on,emitting yellow-green fluorescence（λem=561nm）,and it can be directly observed under the naked eye before and after adding hydrazine hydrate,which changes from light yellow to colorless in sunlight,realizing fluorescence detection.In additon,the probe is highly selective and can be well distinguished from other reducing substances,the application of cell ratio fluorescence imaging shows that it has a response to hydrazine hydrate in cells as well.Bisulfite（HSO₃^-）,as a common additive,is widely used in foods and beverages as preservatives and antioxidants.Studies have found that elevated levels of bisulfite can affect people’s skin and respiratory tract,leading to asthma,gastrointestinal and allergic reactions.Therefore,it is very important to develop a fluorescent sensor with high selectivity and sensitivity for the detection of bisulfite.The experiment in Chapter 3 of the thesis is based on the mechanism of Fluorescence Resonance Energy Transfer,using naphthimide fluorophores as donors and indole hemicyanine fluorophores as acceptors groups.After adding HSO₃^-,the probe showed a visible color change from red to colorless and a fluorescence change from red to blue,realizing the ratio detection of HSO₃^-.In addition,the probe can quickly respond to HSO₃^-（10min）and the low detection limit（27.6n M）of 1,4-Michael addition reactions,and has high selectivity without interference from other active sulfur substances.