Synthesis And Properties Of Al³⁺,Zn²⁺and Cd²⁺ Fluorescence Chemosensor Based On Diarylethene Schiff Base Derivative

Until now,many traditional analytical methods have been developed for detecting metal ions.However,these methods required trained skilled operator,time-consuming sample prepared procedures and the expensive equipment.Fluorescent sensors have become the most effective means for detecting the metal ions because of its high sensitivity and simplicity as well as ease of signal transduction.Therefore,designing the fluorescence chemosensors for the metal ions detection are critical importance in biologic environmental and analytical chemistry.Among the various reported phtotochromic materials,diarylethene is one of the most promising candidate for photoresponsive materials.Diarylethene derivatives are extensively used in constructing fluorescence probes for its out-standing fatigue resistance,thermal stability and rapid response towards light.It is noteworthy that conjugation with suitable functional group have been a popular strategy in the design of diarylethenes fluorescence chemosensors.In summary,three simple fluorescence chemosensors based on diarylethene Schiff base compounds were designed and synthesized and its photochromic,fluorescent switches and metal ion recognition were systematically investigated.The main contents of this dissertation are as follows:In chapter 1,we summrise the basic property of diarylethene derivatives and its application in the recent 5 years.In addition,by the introduction of certain functional moieties,diarylethenes can not only respond to light but also to some external stimuli,such as cations,anions,acid and base.And finally,we give a brief summary about the main contents of this paper.In chapter 2,a new fluorescence chemosensor based on salicylaldehyde diarylethene Schiff base derivative?DTE-1o?has been synthesized and its structure was confirmed by ¹H NMR,¹³C NMR and LRMS analysis.The photochromic and fluorescence photoswitching property of DTE-1o were carried out by irradiation with UV/vis light.The sensor DTE-1o exhibited sensitively and selectively towards Al³⁺and Zn²⁺with different fluorescence signal in methanol solution.The sensing behavior was investigated by the Job's plot,the LRMS analysis and the ¹H NMR titration analysis method.The LOD were determined to be 2.87×10^-8 mol L^-1 for Al³⁺and 1.05×10^-7 mol L^-11 for Zn²⁺,respectively.The multifunctional characteristics of DTE-1o were used to construct a logic gate with the emission intensity of DTE-1o as output and the stimulation of light and chemical species as input.In addition,the diarylethene derivative?DTE-1o?exhibited sensitively and selectively towards Zn²⁺in the THF solution.In chapter 3,a novel photochromic pyridine diarylethene containing 1-H-indole-2-carboxylic acid hydrazide via Schiff base linkage was designed and synthesized.It can be used as a fluorescent probe for zinc and cadmium ion detection in THF.Among the various metal ions tested,zinc and cadmium ions induced red-shifted emissions of the probe from 439 nm to 550 nm,respectively.Both the formation of the 1:1complexes between DTE-2o and the Zn²⁺and Cd²⁺,and the sensing mechanim were confirmed by ¹H-NMR characterization techniques.In chapter 4,a new fluorescent probe?DTE-3o?based on salicylaldehyde diarylethene derivative containing 2-?2?-hydroxyphenyl?benzothiazole unit via Schiff base linkage was synthesized,and its structure was confirmed by ¹H NMR,¹³C NMR.The sensor can be used as a fluorescent probe for cadmium ion detection in DMF.DTE-3o showed very weak emission intensity at 623 nm,and it blue-shift 49 nm upon binding Cd²⁺with remarkable fluorescence enhancements.Moreover,upon irradiation with 297 nm light,the absorption maximum of DTE-3c-Cd²⁺was observed at 580 nm,which was blue-shifted 73 nm,as compared to that of DTE-3c.