Synthesis And Properties Of Multifunctional Al³⁺ And Zn²⁺ Fluorescence Sensor Based On Novel Diarylethene

Metal ions play an important role in environmental science and human biological expression,thus,the sensitive monitoring of metal ions is vital for environmental protection and water safety.Among various detection methods,fluorescence detection is one of the most effective methods for the detection of analytes in the presence of interfering matrices,exhibiting high sensitivity,excellent selectivity,shorter response times,and low detection limits.Diarylethene derivatives are considered to be an outstanding representative of this kind of photoswitching materials,due to their good thermal stability,high fatigue resistance and short photoresponse time,as well as high ring-closure and ring-open quantum yields.This unique photochromic property and reversible molecular structure show a wide range of applications in smart materials,chemical probes,optical switches,and memory.More and more diarylethene sensing molecules have been developed to detect metal ions in ecological environment.Here,three diarylethenes were designed and synthesized,which exhibited high selective recognition of Al³⁺and Zn²⁺,and systematically studied optical properties and recognition mechanism.In chapter 1,the structure and identification principle of the fluorescent chemical sensor were briefly outlined,and the excellent properties and practical applications of diarylene were systematically introduced.Based on the above content,the research topic of this paper is proposed.In chapter 2,a novel diarylethene（1O）modified by hydrazide units was designed and synthesized.In acetonitrile,1O displayed excellent selectivity and sensitivity to Al³⁺.Upon addition of Al³⁺,the emission intensity enhanced 70-fold.Further,the potential response mechanism of 1O toward Al³⁺was proposed and verified by ¹H NMR titrations and mass spectrometry analysis.The stoichiometric ratios of the sensor with Al³⁺appeared to be 1:1 with the detection limit of 0.073μM.In addition,the feasibility of sensor 1O in real water samples was demonstrated by experimental results,and it also has successfully designed as test strips.In chapter 3,a novel diarylethene（2O）modified by thienopyrimidin was designed and synthesized.2O could exhibited excellent photochromic properties and switching characteristics in acetonitrile.When Zn²⁺added to 2O,the fluorescence color changed from blue to yellow,indicating that a large emission peak shift.At the same time,2O could recognize Zn²⁺in the presence of other metal ions,and the detection limit is as low as 0.03μM.Subsequently,the binding method of 2O and Zn²⁺was explored through¹H NMR,Job’s plot experiment and high-resolution mass spectrometry data.In addition,the potential value of sensor 2O was also explored by preparing test strips and logic circuits.In chapter 4,designed and synthesized the compound 3O by linking the diarylethene parent with thienopyrimidin structure.Unlike compound 2O,different modifications are made on the diarylethene unit.When Al³⁺added to 3O,fluorescent color changes from dark to bright yellow.Subsequently,through ¹H NMR titration,mass spectrometry,and Job’s plot experiment,the binding mode of compound 3O and Al³⁺was obtained.It has also been applied to the construction of test paper and real water detection.