Synthesis And Properties Of Cu²⁺?Zn²⁺?Cd²⁺ Chemosensors Based On Diarylethene With Nitrogen Groups

Among the various available techniques for the detection of cations and anions,fluorescence detection is more preferred,since fluorescent chemosensors have distinct advantages such as high selectivity,high sensitivity,low cost,fast response and easy operation.Among these reported sensors for recognition of anions and cations,diarylethenes are very promising molecular due to their remarkable fatigue resistance,thermal stability and multi-responsively photoswitchable properties under various stimulations?UV/vis lights and chemical substances?.Cu²⁺plays an important role in biological,environmental and chemical research field.Therefore,the development of fluorescent chemosensors that can rapidly detect and monitor Cu²⁺has aroused considerable attention.Some available Zn²⁺sensors have difficulty in distinguishing Zn²⁺from Cd²⁺,since Cd²⁺is in the same group of the periodic table and has similar properties.Therefore,the design of a highly selective and sensitive fluorescent sensor for Zn²⁺detection without interference from other metal ions,especially Cd²⁺,is of vital importance.CN^-has attracted extensive attention and research due to its high toxicity to the biology and environment.So far,a great deal of effort has been devoted to design and synthesize various diarylethene chemosensors for selective detection of metal cations Cu²⁺,Zn²⁺,Cd²⁺and the anion CN^-.However,there are few reports of diarylethene fluorescent chemosensors that can efficiently identify and detect Cu²⁺,Zn²⁺,Cd²⁺and CN^-.Therefore,seven diarylethene derivatives containing nitrogen groups have been designed and synthesized,and their photochemical properties and selectivity to anions and cations were systematically investigated.The main contents of this paper are as follows:In chapter 1,the research progress of diarylethene compounds,the basic properties and applications of diarylethene compounds,the research progress of fluorescent chemosensors and the research progress of diarylethenes as Cu²⁺,Zn²⁺,Cd²⁺,CN^-chemosensors are introduced.Finally,the research content of this topic is put forward.In chapter 2,a novel photochromic diarylethene DN-1 containing a benzofurazan structure has been designed and synthesized,and its properties were systematically tested and further studied.The compound DN-1 exhibited favorable photochromism and fluorescent switching properties in aqueous acetonitrile,and DN-1 could specifically detect and recognize Cu²⁺.The complexation sites and patterns of DN-1 and Cu²⁺were further confirmed by nuclear magnetic resonance and mass spectrometry.In chapter 3,one diarylethene compound DN-2 containing pyrazolyl hydrazide group was designed and synthesized,and its properties were systematically tested and further studied.The compound DN-2 could selectively recognize Zn²⁺and Al³⁺,but also could specifically detect and identify CN^-and also respond to acid and alkali.Therefore,DN-2 could be used as a multiple chemosensors that could selectively recognize anion and cation.In chapter 4,two diarylethene compounds DN-3 and DN-4 containing pyrimidine hydrazide group were designed and synthesized,and their properties were systematically tested and further studied.Among them,DN-3 exhibited remarkable fatigue resistance and could selectively recognize Zn²⁺.The complexation sites and patterns of DN-3 and Zn²⁺were further confirmed by NMR and MS.DN-4 could selectively recognize and distinguish Zn²⁺and Cd²⁺in methanol solution.Thus it could be used as dual-ion fluorescent sensor.In chapter 5,three diarylethene compounds DN-5,DN-6 and DN-7 containing thiosemicarbazide group were designed and synthesized.Their properties were systematically tested and further studied.Among them,DN-5 could selectively identify and distinguish Zn²⁺and Cd²⁺and was also responsive to acid and alkali.The compound DN-6 was responsive to acid and alkali.The compound DN-7 showed favorable photochromism and fluorescent switching properties.