The Near-infrared Fluorescent Probe For The Detection Of F-and N₂H₄ Based On ICT Machanism

Fluoride is an indispensable component in the teeth and bones,but excessive intake will cause human fluorine poisoning,leading to urolithiasis,etc.;Hydrazine is widely used because it is a highly reactive base and has a strong nucleophilicity.However,it is unstable and inhaled by the human body can cause liver and kidney damage.Therefore,it is necessary to develop a sensitive,reliable,highly selective method for detecting F^-and N₂H₄ in the environment or organisms.In view of the advantages of near-infrared fluorescent probes,such as weak autofluorescence interference,low light damage,and good tissue permeability,we designed and synthesized a new,easily available,colorimetric and near-infrared?665 nm?fluorescent probe?IS-NR-F?with large Stokes shift??127 nm?and the contrast probe IS-F in Chapter2.F-triggered a specific desilylation reaction made the ICT effect between the donor phenolate anion and the acceptor malononitrile of IS-NR-O turned on,thereby realizing the response of probe to fluoride ions.Because the malononitrile group of the contrast probe IS-F was replaced by carbonyl oxygen,the ICT effect of the generated IS-O was weaker than that of IS-NR-O,only emitting at 568 nm and a Stokes shift of 122 nm.In addtion,the probe could achieve dual colorimetric and fluorescent response with excellent selectivity to fluoride ions.The probe also maintained a good linear relationship with fluoride over a wide range of fluoride ions concentrations?0.38-6.84 ppm?and has a low detection limit of 0.09 ppm for fluoride.The detection mechanism was further confirmed by ¹H NMR,ESI-MS and TLC calculations.Lastly,the probe IS-NR-F has been successfully used for the detection of F^-in tap water and several commercial toothpaste samples,and F^-imaging detectionin HeLa cells.In chapter 3,we further used the near-infrared emission characteristics of IS-NR-O to synthesize the fluorescent probe IS-NR-NH.The strong nucleophilicity of hydrazine?N₂H₄?could specifically induce the deacetylation of the acetyl group on the probe IS-NR-NH,enabling the ICT function of probe to be turned on and the fluorescence intensity to be enhanced,and finally the specific detection of N₂H₄ was achieved.When the probe was in the presence of a variety of analytes(HCO₃^-,SO₄^2-,Cl^-,SO₃^2-,CO₃^2-,Ac^-,Br^-,NO₃^-,NO₂^-,HSO₃^-,I^-,F^-,Mg²⁺,Co²⁺,Cd²⁺,Zn²⁺,Pb²⁺,Cr³⁺,Fe³⁺,Al³⁺,Mn²⁺,Ca²⁺,Ba²⁺),specific colorimetric and fluorescent recognition of N₂H₄ could still be achieved.Meanwhile,in a system with a volume ratio of DMSO to PBS buffer solution?20 mM,pH 7.4?of 6:4,the probe IS-NR-NH showed a good linear relationship in the range of N₂H₄ concentration from 0.02 mM to 0.4 mM,and its detection limit was as low as 0.2?M.Finally,the probe was successfully used for the detection of N₂H₄ in HeLa cells by near-infrared fluorescence imaging.