Synthesis Of New Pyrazoline-based Fluorescence Probes And Its Application In Metal Ions

Fluorescence molecular probe structure wit h multi-conjugated system,or in the conjugated system to increase the strong electron donor groups,as well as molecular rigidity,which makes the synthesis of the probe in the ultraviolet-visible-near infrared region to produce a stronger fluorescence e ffect.In all fluorescent molecular probe systems,pyrazoline probe compounds have the advantages of rigid planar structure,higher fluorescence quantum yield,higher hole-transport efficiency and stronger blue fluorescence.Based on these conditions,new type of probes based on the pyrazoline structure were designed and synthesized to detect the metal cationic,some conclusions were obtained through the test.The main contents are shown as following:The pyrazoline probe D/L/M with excellent fluorescence p roperties were designed and synthesized.Different substituents were introduced on the pyrazoline ring,their optical properties and the effect of probes on the recognition of metal ions were measured by UV absorption spectroscopy and fluorescence emission spectroscopy under different solvent conditions.T ests found that the probe D achieve selective identification of the specific metal ion Cu²⁺ in the aqueous solution.The probe D formed a 1:1 complex with Cu²⁺,resulting in quenching effect.The probe D and Cu²⁺ concentration titration showed a good linear relationship with the lowest detection line 1.16 × 10-7 M.The reversibility of the complexation of probe D with Cu²⁺ and the low toxicity of probe D can be used in cell imaging.Those indicated that probe D has a potential practical value for rapid a nd timely identification of Cu²⁺.The recognition performance of the probe L on target ion Cu²⁺ did not change in the mixed solution but it could identify Cu²⁺ in the environment of complexity and interferenc e.It was also found that Cu²⁺ had better quenching effect on probe L.And it was found that the probe L could complex with Cu²⁺ on the recognition group,and the anthracenyl group and naphthyl group could also help to enhance the recognition ability of the probe.The introduction of the probe M at the 1-position benzothiazole at the pyrazoline ring showed a highly efficient and sensitive selection for different target ions Zn²⁺/Cd²⁺.And the probe M complexed with the target ion Zn²⁺/Cd²⁺ produced different from the previous fluorescence enhancement phenomenon.The absorption peak of the complexes of probe M and Zn²⁺ was also relative movement.This indicates that the benzothiazole group of probe M had critical effect on the probe M recognized Zn²⁺/Cd²⁺.To sum up,three different probes,D/L/M,were synthesized by introducing different substituents on the pyrazoline ring,and their optical properties were investigated respectively.We can conclude that three pyrazoline fluorescent probes showed its excellent selective selectivity,complexation ability,and the reversibility of the complex system,which provides a basis for further investigation of metal cations in future fluorescent probes.