Synthesis And Application Of Ratio Fluorescence Probes Based On Pyridine [1,2-a] Benzimidazole Fluorescence Group

The main methods used to detect ions are capillary electrophoresis,atomic emission spectrometry,X-ray microanalysis,electrochemical analysis,etc.Although these methods have good results,there are some problems such as expensive instruments and equipment,complex sample pretreatment process and so on,which limit their wide application in practical detection.Because the probe has the advantages of fast response,high sensitivity,good selectivity and low detection cost,it has attracted wide attention.However,in practical analysis,most fluorescent probes are single signal enhancement or attenuation probes,which are often interfered by many external factors（such as temperature,probe concentration,instrument slit,photobleaching,etc）and produce false positive results.Ratio fluorescence probe can detect target analyte through the ratio of fluorescence intensity at different wave-lengths as signal output.It can solve the above problems well.At present,there are few fluorescent groups used to design and synthe-size ratio fluorescent probes,such as naphthalimide,coumarin,BODIY,rhodamine and so on.Our group synthesized a new pyrido[1,2-a]benzimi-dazole fluorescent group simply and effici-ently through a new series reaction,and applied it to the design and synthesis of fluorescent probes.In the foreword,the structure and design principle of fluorescent molec-ulear probes are introduced.The application and synthesis methods of pyrido[1,2-a]benzimidazole derivatives are briefly introduced.The research prog-ress of ratio fluorescent probes are reviewed.In the first part,the synthesis and application of a ratio fluorescent probe TMU-1 for detecting SO₃^2--based on ICT mechanism are introduced.The probe TMU-1 showed high selectivity,sensitivity,fast response speed and low detection limit for SO₃^2-.In addition,the probe can be used to detect the content of SO₃^2-in dry white wine.In the second part,the synthesis and application of a mitochondrial targeting ratio fluorescent probe TMU-2 for detecting SO₃^2-based on FRET mechanism are introduced.The probe TMU-2 has unique fluorescence select-ivity,high sensitivity,strong anti-interference ability to other ions and low detection limit.Most importantly,the probe has been successfully applied to fluorescence imaging of endogenous bisulfite in mitochondria of glioma cells.The third part introduces the synthesis and application of a ratio fluorescent probe TMU-3 based on FRET mechanism for detecting Hg²⁺.The probe TMU-3 chooses colorless rhodamine derivatives as energy acceptors and pyridine[1,2-a]benzimidazole as donors.Because its maximum emiss-ion wavelength coincides well with the absorption spectrum of Rhoda-mine,the probe TMU-3 is selected as energy donor with an energy transfer efficiency of 87.3%.The probe has unique fluorescence selectivity,high sensi-tivity,strong anti-interference ability and low detection limit for Hg²⁺.In addition,it can also be used for Hg²⁺imaging in living cells.