Design,Synthesis And Application Of Fluorescence Probe For Rapid Detection Of Hcl O Based On Phenothiazine Fluorophore

Photochemical sensors can make use of light,a convenient,fast,green and clean tool that can be found everywhere in life,thus enabling fast and sensitive specific identification of small molecules in the environment,in cells and in living organisms.In recent years,fluorescent probes have received a lot of attention from researchers and related practitioners due to their many advantages such as high sensitivity,high selectivity and bio-friendliness,and more and more excellent fluorescent probes have been reported.Therefore,it is necessary to design and synthesize fluorescent probes with excellent performance,good biocompatibility and simple synthetic routes.The phenothiazine moiety（PTZ）has a butterfly-type non-planar structure,which can effectively suppress the fluorescence quenching（ACQ）phenomenon caused byπ-πstacking of molecules,and the structure of phenothiazine contains electron-rich nitrogen and sulfur atoms,which has strong electron-giving ability and easy modification,and phenothiazine-related derivatives are widely used in optoelectronic materials,fluorescence analysis and other fields.Therefore,in this thesis we designed and synthesized three fluorescent probes based on the backbone structure of phenothiazine and modulated the optical sensing properties of the fluorescent probes by replacing intermediates with different properties,and explored the reaction recognition mechanism of the three fluorescent probes to HClO by means of high-resolution mass spectrometry,with the main research as follows:1.By combining phenothiazine with a positively charged pyridine salt structure,a water-soluble and easy-to-synthesize"ON-OFF"yellow fluorescent probe PMP with a relatively long emission wavelength was designed and synthesized for the specific detection of HClO and successfully applied to the detection of actual water samples and paper-based sensing materials.At the excitation wavelength of 370 nm,the probe PMP reacted with HClO and showed yellow fluorescence at 580 nm,and the fluorescence intensity of the probe increased rapidly and reached the steady state within 20 s.The detection limit was calculated to be 2.03μM by fluorescence titration experiment,and the response speed was fast and the detection limit was low,which was successfully applied to the detection of HClO in real environment.2.An enhanced green fluorescent probe PTZ-IP was designed for the specific detection of HClO by combining imidazo[1,2-α]pyridine with phenothiazine fluorophore.The probe PTZ-IP uses phenothiazine as the recognition group and imidazo[1,2-α]pyridine as the fluorescent group to detect HClO by the change in fluorescence visible to the naked eye before and after the reaction with HClO.The probe PTZ-IP showed bright green fluorescence at 546 nm after the reaction with HClO at 390 nm excitation wavelength.The probe PTZ-IP showed excellent selective immunity to HClO recognition,a rapid increase in probe fluorescence intensity within10 s,and a calculated detection limit of 0.58μM by titration experiments,with a fast response rate and low detection limit.More importantly,the probe PTZ-IP was successfully applied to live cell imaging and localization of lysosomes.3.A ratiometric fluorescent probe PT-HBI was designed and synthesized by combining phenothiazine with the green fluorescent protein（GFP）chromophore HBI using morpholine as the targeting group for selective recognition of HClO and was successfully applied to cell imaging and targeting lysosomes.Phenothiazine is linked to HBI by a double bond,and the emission wavelength is red-shifted due to the increase of the conjugated structure.HClO specifically oxidizes the sulfur atom of the phenothiazine part,and within 60 s the emission wavelength of the fluorescent probe PT-HBI is blue-shifted,and the system changes from orange-red fluorescence to yellow fluorescence with a significant ratiometric fluorescence response(F₅₄₀/F₆₆₀ over 175-fold change).In addition,the probe PT-HBI has been successfully used to construct paper-based sensing materials to detect different concentrations of HClO（using deionized water to dilute the HClO standard solution）.the R/B value enables the quantitative detection of HClO with a linear detection range of 0.1-0.5 m M.in addition,the probe PT-HBI has been successfully applied to determine HClO in real water samples.