Synthesis And Recognition Properties Of Novel Cyanostilbene Derivatives

The aggregation induced emission?AIE?referred to non-emissive fluorescent chromophore emitted in an aggregated state.The fluorescent chromophore with AIE effect emits weak fluorescence or has no luminescence in the good solvent,but aggregates in the poor solvent and emits strong fluorescence.Previous reports indicated that the appropriate structural modification of AIE molecules could endow them highly selective and sensitive host and guest ion recognition performance.Therefore,the structural modification of various functional molecules with AIE effect and the study of their object recognition performance is an important research direction in this field.In this thesis,phenolic hydroxy-cyanostilbene was linked to different alkyl chains by a series of etherification and condensation reactions on the premise of phenol hydroxycyanostilbene.Therefore,a series of cyanostilbene derivatives with different cavities were synthesized and their correlation properties were researched.The main contents are as follows:Firstly,three different lengths of open crown ether chain bridged cyanostilbene dimer were designed and synthesized and their photophysical properties were studied.The results revealed that compounds 5,6 and 7 generated quenched fluorescence after chelation with Fe³⁺,indicating that compounds 5,6 and 7 have good recognition effect on Fe³⁺.Secondly,the cyanostilbene trimers and tetramers with trimethylolpropane and pentaerythritol as bridging chains were designed and synthesized.In addition,we explored the photophysical properties of compounds of 9 and 11 and discovered their fluorescence quenched when chelated with picric acid?TNP?and cyanuric chloride,respectively.The results illustrated that compounds 9 and 11 have good recognition ability with TNP and cyanuric chloride,respectively.Thirdly,a nitrogen-containing cyanostilbene dimer with a chloroacetamide containing ethyl,butyl and hexyl groups as a bridging chain was designed and synthesized,respectively.After exploration of their photophysical properties,we have found that compounds 15,16 and 17 exhibited fluorescence enhancement after complexation of adenine,cytosine and folic acid,respectively,which revealed that compounds 15,16 and 17 could recognize adenine,cytosine and folic acid well,respectively.Fourthly,we designed and synthesized two kinds of closed-loop compounds with different sizes of cavities,such as hydroquinone and catechol and cyanostilbene.The photophysical properties of the compounds revealed their excellent recognition ability for organic molecules.The fluorescence of compound 22 quenched after chelation with thymine,while the fluorescence of compound 23 enhanced after chelation with lysine,indicating that compounds 22 and 23 have good recognition effect on thymine and lysine,respectively.