Design And Synthesis Of Purine-based Fluorescent Probes And Their Application In Metal Ion Recognition

In recent years,fluorescent probes can be widely used in various fields of ecology,biology and clinical medicine because of their advantages such as high sensitivity,high selectivity,fast reaction,simple operation and real-time detection.Therefore,designing and synthesizing high-selectivity and high-sensitivity fluorescent probes for detecting trace metal ions in the environment and biological cells has become a research hotspot in the field of chemistry.The purine skeleton is a nitrogen heterocyclic compound formed by fused imidazole ring and pyrimidine ring.All atoms in the ring are conjugated and coplanar,which is prone to?electron transition.Secondly,purine derivatives are widely distributed in nature and are an important class of living substances that can participate in various biochemical reactions in the body.The 2,6,8,9 position in the purine ring can be connected to various substitution groups through chemical reaction.The structure has great variability,suitable for structural modification and good water solubility.However,there are few studies on the detection of trace metal ions based on purine derivatives designed to fluorescent probes.In this paper,three purine-fluorescent probes are designed and synthesized based on purine derivatives as the precursor,and the related optical properties of these three probes in metal ion detection are studied.A simple,efficient on-off fluorescent probe?CMP?based on coumarin and purine derivatives has been rotationally designed,synthesized and characterized.Interestingly,the novel fluorescent probe CMP exhibited a highly sensitive,selective and quick response?within 1min?to Co²⁺in HEPES buffer solution?p H 7.4?,and with a low detection limit?0.487?M?.Notably,visual color change was observed with the addition of Co²⁺to the probe CMP,its color changed from yellow to pink.Moreover,the binding stoichiometry of CMP with Co²⁺was determined to be 1:1 by Job's plot and MS spectra analysis,and the binding mechanism of them was further demonstrate by density functional theory?DFT?study.This novel probe CMP provided a new method for rapid and naked-eye recognition of Co²⁺with a cheap and easy-to-make process,high efficiency and stable storage.A new“turn-on”fluorescent probe?PTAHN?based on biological purine derivative for detecting Zn²⁺ was designed,synthesized and characterized.The PTAHN exhibited remarkable selectivity and rapid response toward Zn²⁺in DMSO/H₂O solution?9/1,v/v,p H 7.4,HEPES buffer,0.2 m M?.The limit of detection?LOD?for Zn²⁺?61.6 n M?is much lower than the WHO standards?76.0?M?.Meanwhile,an obvious color change can be visually observed by naked eye between PTAHN and Zn²⁺-PTAHN.What's more,the sensing mechanism of PTAHN to Zn²⁺was supported by the Job's plot and density functional theory?DFT?study.Interestingly,the novel probe is cell-permeable and can be successfully applied for detection of intracellular zinc ions in living Hep G-2 cells.A Schiff base-type fluorescent probe,PTAID,based on purine derivative was designed and synthesized.To our delight,this probe PTAID could quickly recognize Pd²⁺and Cu²⁺in HEPES buffer solution without the interfering from other ions.The fluorescent probe PTAID displayed significant and specific fluorescence quenching towards Pd²⁺and Cu²⁺with high selectivity and sensitivity,and accompanied by a visual color change of the probe solution from colorless to yellow.The detection limits of PTAID for Pd²⁺and Cu²⁺in HEPES buffer solution were 0.63?M and 1.19?M,respectively.Moreover,the binding mechanisms of PTAID towards Pd²⁺and Cu²⁺were supported by Job's plot.Finally,the probe PTAID was successfully made test paper to detect Pd²⁺and Cu²⁺in a solid state.