Synthesis And Performance Study Of Zn²⁺ Chemical Sensors Based On Arylhydrazine-containing Diarylethene

Metal ions play a vital role in human life and the natural ecosystem,and zinc ions,as a closely related metal ion,play an indispensable role in human brain development and human growth.With industrialisation in recent years,excessive mining and discharge of mineral resources has made zinc pollution a huge hazard to the natural environment,especially to water resources.Zinc is many times more toxic to fish and other aquatic organisms than to humans and warm-blooded animals,so it is essential to design a sensor that can sensitively detect zinc ions.However,the current research for zinc ion sensors is mainly limited by the following aspects:on the one hand,poor selectivity and complicated synthesis methods,and on the other hand,insensitive detection and poor photosensitivity.In contrast,photochromic diarylethene compounds have shown great application in the fields of information storage and fluorescent switching due to their good thermal stability,fatigue resistance,and photosensitivity.It has been found that the good photosensitivity of diarylethene can be used in chemical sensors,so it is interesting to design and synthesise a chemical sensor with good photosensitivity.In this thesis,three different diarylethene compounds were designed and synthesised on the basis of a diarylethene parent containing an acyl hydrazide structure by introducing specific intermediates via the simplest Schiff base reaction,and their optical properties and selective recognition of zinc ions were systematically investigated.The main studies are as follows:Chapter One:presents an overview of chemical sensors,several response mechanisms of chemical sensors,which include:1.photo-induced electron transfer（PET）;2.fluorescence resonance energy transfer（FRET）;3.intramolecular charge transfer（ICT）;4.excited state intramolecular proton transfer（ESIPT）.There are also advances in the study of the fundamental properties of diarylethene compounds and their applications.Chapter Two:Design and synthesis of diarylethene modified by coumarin 1o.UV spectra of 1o were measured to show that 1o has good photoswitching properties,in addition to 1o exhibits good fluorescence selectivity for Zn²⁺,and its optical properties were characterized.The binding mode was investigated by¹H NMR and mass spectrometry,and it was found that 1o and Zn²⁺are bound in a 1:1 manner.And we successfully applied it to actual water sample determination as well as cell imaging.Chapter Three:Design and synthesis of diarylethene modified by1,3-Dimethyluracil-5-carboxaldehyde 2o.UV spectra of 2o were measured to show that 2o has good photoswitching properties and 2o shows good fluorescence response to Zn²⁺,although Al³⁺interferes with it,but the obvious fluorescence intensity difference still can easily distinguish Zn²⁺.The mode of binding was investigated by¹H NMR and mass spectrometry and it was found that 2o and Zn²⁺were bound in a1:1 manner.Chapter Four:Design and synthesis of diarylethene modified by 3-（benzo[d]thiazol-2-yl）-2-hydroxybenzaldehyde compound 3o.Fluorescence spectra showed that 3o was exclusively recognized by Zn²⁺without interference from any other metal ions.The binding mode was investigated by ¹H NMR and mass spectrometry,and fluorescence enhancement was found to be caused by the addition of zinc ions that suppressed the ESIPT effect within the sensor 3o.