Construction And Properties Of Multifunctional Zn²⁺ And Cd²⁺ Sensors Based On Diarylethene

Zinc,as the important elements of the human body,plays a vital role in the neural signal transmission element,gene expression regulation,cell apoptosis and other physiological and pathological process.Relaxation of zinc intake may lead to a variety of diseases including senile dementia,prostate cancer and diabetes mellitus.Cadmium,as one of the most important heavy metal elements,is widely applied in various agricultural and industrial fields,such as alloy material,rechargeable batteries,colouring agent and agricultural fertilizers.However,excessive amounts of cadmium could harm the respiratory system,nephridium,pulmonary arteries and other important bodily functions through long-term exposure,and are more likely to cause serious environmental problems.Hence,developing effective detection methods for Zn²⁺and Cd²⁺is of great significance in biology and environmental science.Up to now,there are some traditional ion detection methods include AAS?atomic absorption spectrometry?,plasma spectrum,and electrochemical analysis.However,all of these methods require extremely high costs and quite complex instrumentation,and it is inconvenient to supervise rapidly in different environments.Compared to traditional methods,fluorescence analysis has the advantages of sensitivity,simplicity and real-time detection.In recent years,photochromic materials have been used as light switchable functional groups in fluorescence sensors,which obtains high attention because of their fast response,thermal stability,and good fatigue resistance.Among these materials,diarylethene and its derivatives have turned into the most promising photosensitive materials in many fields including information storage,molecular switching,ion recognition,and logic gates.Hence,designing multifunctional diarylethene-based fluorescent sensors for Zn²⁺and Cd²⁺is be of the utmost importance.In this paper,we designed and synthesized three novel diarylethene-based fluorescence sensors.Their photochromism,fluorescent switching and ion recognition properties were studied by various means in detail.In chapter 1,the good properties of diarylethene derivatives,the research background of ion sensors,then this subject was put forward.In chapter 2,a new Zn²⁺fluorescent sensor based on the imidazole and diarylethenes was designed and synthesized.Its photochromic and fluorescent properties induced by light and chemical species were also systematically discussed.In chapter 3,a new Cd²⁺fluorescent sensor based on diarylethene with a benzothiazine unit was designed and synthesized.This sensor displayed excellent fluorescent switches under the stimulus of Cd²⁺and UV/vis lights.In chapter 4,a novel diarylethene derivative containing a hydrazinylpyridine unit was designed and synthesized.Upon stimulated by Cd²⁺and Zn²⁺,the derivative showed a different degree of red-shift of emission wavelength,accompanied by two disparate fluorescent colors,and both colors could be demonstratively distinguished by the naked eye.