Synthesis And Spectroscopic Properties Of Fe ^{3 +} Fluorescence Probe With Fenimidazole - Coumarin

In view of the important role of Fe³⁺ in biology and environment, combined with the excellent characteristics of imidazole compounds and coumarin compounds in selectivity,sensitivity, light stability, etc., a series of fluorescent probes with double fluorophore of phenanthroimidazole and coumarin to recognize Fe³⁺ were designed and synthesized. They are 6-methyl-4-[4-（1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl）aniline methylene]-2Hchromen-2-one（P1）, 6-methyl-4-[3-（1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl）aniline methylene]-2H-chromen-2-one（P2）, 4-[4-（1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl）aniline methylene]-2H-benzo[H]chromen-2-one（P3）, 4-[2-（1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl）aniline methylene]-2H-benzo[H]chromen-2-one（P4）, 4-methyl-7-hydroxy-8-[2-（1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl）anilinemethylene]-2H-chromen-2-one（P5）.And the characterization and validation of the structure of these compounds were completed by 1H NMR, 13 C NMR, IR and melting point.In different proportion of DMF and HEPES buffer solution（pH = 7.4）, the polarity of the solvent for probe P1^P5 were discussed. In solvent system of DMF and HEPES buffer solution（v/v = 7/3,pH=7.4）, the study of spectral properties of probe P1^P5 with various metal ions were completed. In the excitation wavelength of 365 nm UV light, it becomes black from blue when Fe³⁺ was added. It can be seen clearly that Fe³⁺ causes the fluorescence quenching of probe P1^P5. The fluorescence emission spectra of further validates the fluorescence quenching effect of Fe³⁺ were carried out to probe P1^P5, and it can be seen that probe P1^P5 have good selectivity and anti-jamming capability to Fe³⁺. At the same time, the influences of solvent polarity and pH to the recognition of probe P1^P5 to Fe³⁺. The titration experiments show that the fluorescence intensity of probe P1^P5 decreases rapidly with increasing concentration of Fe³⁺ until almost completely quenched, and that probe P1^P5 has a very high sensitivity by calculating the detection limit. The response time between probe P1^P5 and Fe³⁺ was tested, it works in 0.5 min. It is visibled that probe P1^P5 can be respond to Fe³⁺ rapidly, with good timeliness.