Fluorescence And Chiral Spectral Responses Of Tetraphenylethene-based Tetracationic Cyclophanes For Nucleotides

The traditional supramolecular macrocycles(e.g.crown ether,cyclodextrin,cucurbituril,pillararene,calixarene)mainly binds to the guest molecules through non-covalent interactions and produces some specific responses.Because of its special hydrophobic cavity,macrocycles can efficiently bind guest molecules and construct molecular devices with different functions with different modules.For example,fluorescence sensing molecules with excellent performance can be developed by using the modification of fluorophore for the detection of anions,cationics,neutral molecules and biomolecules.Its application fields include biology,medicine,environment,catalysis and function materials.This dissertation consists of three chapters.In the first chapter,the research progress of supramolecular chemistry is briefly introduced,and the structural characteristics,application and research significance of cyclophanes are emphatic introduced,and the synthesis strategy of angle control to construct supramolecular macrocyclic host is elaborated in detail.After analyzing the above research results,the topic selection and significance of this paper are proposed.In the second chapter,two different tetracationic cyclophanes with different linker were designed and synthesized in the absence of templates.They had a large hydrophobic and cationic cavity for molecular recognition and two meso-racemic tetrastyrene(TPE)units for fluorescence and chiral response.In the third chapter,the structure of the host molecule is improved based on the results of the second chapter.Cyclophanes 3 with more solid cavity and larger opening was designed and synthesized.Because the free rotation of double bond of tetrastyrene unit was further restricted,the fluorescence properties and fluorescence quantum yield of monomer were significantly improved.However,the tetrastyrene units that can carry out conformational transformation are difficult to bind to the large grooves of DNA,resulting in poor chiral response signal.Through the different fluorescence and chiral responses of different cyclophanes to the same guest,the influence of macroring structure on guest recognition was confirmed,which provides a new idea for the design of functional molecules in the future.The cationic cyclophanes based on tetrastyrene have potential applications in the fields of fluorescent materials and biological probes.