Studies On Construction And Properties Of Diarylethenes Al³⁺ Chemosensor Containing N-heterocyclic Cycles

Photochromic diarylethenes are one of the most promising organic photo-responsive materials with excellent photoactivity,thermal stability and fatigue resistance.There are broad application prospects of diarylethenes in the field of optical memories,molecular switches,photochemical sensors,and so on.In this thesis,17 novel diarylethene derivatives were designed and synthesized,and systematically investigated their photochromic,fluorescent switches,host-guest interactions,and so on.In addition,some compounds with ideal properties were selected to explore their applications as molecular logic gate circuits and in fluorescent cell imaging.The detailed research work are described below:In chapter 1,the design principles of photochemical sensors and interaction mechanisms were reviewed.In combination with the current research on photochromic diarlethenes,the research progress and the types of diarylethene-based photochemical sensors were introduced,and the novel diarylethenes in this thesis were described.In chapter 2,10 asymmetric photochromic diarylethenes containing reactive groups were designed and synthesized.The photochromic properties of these diarylethenes in different phases such as solution,solid and crystalline were studied.The results showed that the hetercyclic aryl groups had effects on their properties.The diarylethenes DE1o⁷o exhibited good photochromic reactivity in solid phase,while the thiophene-naphthalene hybrid compounds DE-8o⁹o showed weak photochromism in solid phase.In addition,the reactive groups not only had notable effects on the properties of these diarylethenes,but led to decreasing of their fatigue resistance.In chapter 3,2 new photochromic diarylethenes with a dithienobenzoimidazolyl?DE-11o?or triazole-phenoxymethyl-benzothiazolyl?DE-12o?were designed and synthesized.Their photochromism,fluorescent switching property,acid/base response,and metal ion recognition were systematically investigated.The results indicated that DE-11o showed a“gated photochromic”phenomenon upon stimulation of acid/base and light.The fluorescence emission intensity could be remarkably enhanced in the process of protonation.Moreover,both of them showed excellent selective recognition for Al³⁺,and the interactions between DE-11o/12o and Al³⁺caused 6 and 4-fold enhancements in their fluorescence intensity,respectively,accompanied by an evident fluorescent color change from dark to bright blue and green,respectively.The results demonstrated that DE-11o/12o could act as“Turn-On”fluorescence sensors for Al³⁺,and two combinational logic circuits were constructed on a single molecule platform based on their multi-controllable characteristics.In chapter 4,2 new photochromic diarylethenes bearing a naphthol/quinoline hydrazide unit?DE-13o/14o?were synthesized via a aldehyde ammonia condensation reaction.Their multiple response behaviors induced by light,acid/base,and metal ions were investigated systematically.Diarylethene DE-13o was highly sensitive and selective to Al³⁺in acetonitrile,while DE-14o exhibited selective recognition Al³⁺in methanol.DE-13o and DE-14o selectively formed a 1:1 and 2:1metal complexes with Al³⁺,respectively,resulting in a“Turn-On”fluorescence signal.Moreover,DE-13o could penetrate into HeLa cells and be used for the determination of intracellular Al³⁺.In chapter 5,3 new photochromic diarylethenes with a pyrazine hydrazide group were synthesized?DE-15o¹7o?.The species of diarylethenes and the different six-membered aryl rings?phenyl,pyridyl,and phenolic group?showed significant effects on the multiple response behaviors of these diarylethenes.The results showed that DE-15o¹7o exhibited excellent photochromic,and their cyclization quantum yields were determined to be 0.62?DE-15o??0.27?DE-16o?and 0.14?DE-17o?,respectively.Their interactions with metal ions showed that only DE-17o could be used as a highly selective“naked-eyes”colorimetric sensor for Cu²⁺.Furthermore,the fluorescence of DE-16o/17o could be remarkably enhanced in the presence of Cd²⁺and Al³⁺,respectively.Therefore,DE-16o/17o could serve as fluorescence enhancements photochemical sensor for the detection of Cd²⁺and Al³⁺.In chapter 6,conclusions and prospectives were presented.