Construction And Modulation Of Multi-responsive Fluorescent Supramolecular Assembly

In recent years,multiple-responsive molecules have been served as building units to assemble functional materials with expected properties,which has become the attractive issue.Surfactants and dye molecules with opposite charges are used to construct supramolecular assembly by the Ionic Self-Assembly（ISA）strategy.This construction method has the unique advantages of simplicity,reliability and flexibility,which has potential applications in the field of designing functional optoelectronic materials.We synthesized cationic ferrocenyl surfactant,16-alkyl（Ferrocenyl-methyl）Ammonium Bromide（Fc16AB）,which was coordinated with anionic dye molecules alizarin red（AR）,Orange G（OG）and fluorescein sodium（FS）,respectively by the ISA method to construct multi-responsive fluorescent supramolecular assembly.The morphology,structure and fluorescence behavior of these assemblies were modulated by redox species,pH andβ-cyclodextrin（β-CD）inclusion,and the responsive mechanism was studied.The related work is as following:1.The responsive fluorescent assembly was prepared by complexing Fc16AB and AR molecules via the ISA method.The microstructures of the assembly were modulated using redox species,pH orβ-CD inclusion.Various microstructures such as rod-like,dendritic and petal-like clusters were obtained.In addition,the fluorescence intensity of the assembly was controlled by changing the radio of Fc16AB,the fluorescence intensity reduced when the radio of Fc16AB increased.Moreover,adding redox species could trigger the reversible transformation of the fluorescence intensity,and the obtained assembly can be served as novel fluorescent molecular switch.2.Using ISA method,Fc16AB and OG molecules were combined to prepare supramolecular assembly with quadruple fluorescence switching behavior,the compelx radio of Fc16AB and OG was 2:1.By adding Ce（SO₄）₂ andβ-CD inclusion,the assembly with different morphologies（including rod-like fiber,spindle micelle and fiber bundle）was obtained.In combination with the morphological transformation,the mechanism of fluorescence quenching and fluorescence enhancement caused by each modulation were discussed in details,and the assembly has potential applications in multifunctional photoelectric devices.3.Fc16AB and FS were complexed to obtain Fc16AB-FS assembly,which exhibited multiple responsivenesses to modulation of redox andβ-CD inclusion.The mechanism of the fluorescence quenching caused by Photoinduced Electron Transfer（PET）and the fluorescence enhancement caused byπ-πstack was discussed carefully.Then,water-in-oil reverse microemulsion method was used to prepare nanoparticles with fluorescent properties in the solid state.Fluorescent nanoparticles Fc16AB-FS/SiO₂ showed yellow-green fluorescence,which could be used to prepare complex fluorescent film to obtain white-luminescence by combining with commercial blue LED.By combining ISA with reverse microemulsion method,a novel synthetic method of fluorescent nano-assembly was proposed,which broadened the application of template method in preparing fluorescent nanomaterials.