Synthesis And Ion Recognition Properties Of Ferrocenyl Imidazo[4,5-b] Pyridine Sulfur-containing Derivatives

Hg²⁺is a highly toxic metal ion,which can easily lead to many serious health and environmental problems.Therefore,the design and synthesis of new organic small molecules for the determination of Hg²⁺are extremely important for biology,chemistry,and environmental science.In this paper,2-ferrocenyl imidazo[4,5-b]pyridine is used as the parent to design and synthesize 6 kinds of 2-ferrocenyl imidazo[4,5-b]pyridine with different substituents at the 4 and 5 positions New type of ion probes L₁-L_6.Through the Suzuki cross-coupling reaction method,the reaction conditions were optimized at the same time to increase the yield to 80%-88%,Then,its molecular structure is characterized by various related methods such as nuclear magnetic resonance spectrometer,liquid chromatography-mass spectrometer,infrared spectrophotometer,ultraviolet spectrophotometer and so on Using square wave voltammetry（SWV）,cyclic voltammetry（CV）,UV-Vis spectroscopy and fluorescence emission spectroscopy,under optimized test conditions,study the recognition performance of 6 compounds against 19common metal cations and 8 anions,Preliminary analysis of the influence of its molecular structure on ion recognition performance.The detection sensitivity of the probe L₁is the highest and the recognition effect is the best.The detection limit can reach the order of 3.2×10^-8,while the detection limit of the probe L₂-L₆is in the order of 10^-7-10^-6;Other interfering ions have no obvious interference effect on the performance of the probe L₂-L₆for selective recognition of Hg²⁺.L₁has a fluorescence quenching phenomenon in the presence of Hg²⁺.After adding I^-,the fluorescence intensity can be restored to the initial level.This cycle process can cycle more than 5 times.Through ultraviolet titration,Job’s plot,mass spectrometry and other experimental data,it is found that L₁with Hg²⁺are combined in 2:1 form,while the remaining probes L₂-L₆with Hg²⁺are combined in 1:1 form;At the same time,the probe L₆can selectively recognize the anion HSO₄^-.By analyzing the structure and properties of probes L₁-L_6,it is found that introducing different substituents at the 5-position of2-ferrocenyl imidazo[4,5-b]pyridine has a better ion recognition effect.