Study On ?-cyano-functionalized Diarylethene-based Fiourescent Photoswitches And Their Constructed Photoswitchable Nanoparticles

Phototunable fluorescent nanoparticles are a class of materials with dynamic changes in fluorescence at the nanometer scale.In this study,we designed and synthesized two new fluorescent ptotoswitchable molecules containing ?-cyanostilbene-based photosensitive motifs,then their photoswitable properties and AIE properties are studied.Using mini-emulsion polymerization mechanism to prepare light-responsive fluorescent nanoparticles,and to study the surface morphology and photoswitchable properties of the nanoparticles.The specific research content is as follows:1)Two new fluorescent photoswitchable molecules FS-1 and FS-2 are designed and synthesized,in which these two molecules have the same?-cyanodiarylethene and pyridine group.The difference is that the FS-1 molecule contains a triphenylamine group and the FS-2 molecule includes a dimethylaniline group.Through absorption spectroscopy,fluorescence spectroscopy,hydrogen nuclear magnetic spectrum and other characterization methods,it was confirmed that FS-1 and FS-2 molecules have the characteristics of reversible photoisomerization.Moreover,the significant fluorescence intensity contrast of the two molecules before and after photoisomerization could be observed.In particular,FS-1 molecule shows obvious AIE characteristics,while FS-2 molecule exhibits aggregation-induced fluorescence quenching characteristics.Furthermore,the above performance differences between them are discussed and analyzed based on Gaussian simulation.2)The FS-1 molecule is used as the proton acceptor,and the C6M acid serves as the proton donor for hydrogen bond assembly to obtain the FS-1-AHBA fluorescent assembly.The liquid crystal polymerizable monomers,polymerizable amphiphilic molecules,etc.,are mixed and then a series of light-controllable fluorescent nanospheres are prepared through miniemulsion polymerization.The surface morphology and light switching performances of the consequent nanoparticles are investigated.The results show that the greater the degree of cross-linking of the liquid crystal network,the worse the light switching performance of the nanoparticles.By changing the content of FS-1-AHBA fluorescent assembly,the gradient experiment results show that the content of FS-1-AHBA has little effect on the surface morphology and light switching performance of the nanoparticles.In summary,two photoswitchable fluorescent molecules FS-1 and FS-2 are prepared in this work,and the FS-1 molecule with AIE characteristics is selected to assemble the FS-1-AHBA fluorescent assembly.Finally,the phototunable fluorescent nanoparticles are obtained through mini-emulsion polymerization.The phototunable fluorescent nanoparticles have potential applications in the fields of biological imaging,anti-counterfeiting and information encryption.