| The in-depth study of chirality has become indispensable in the process of human learning nature.By exploring nature’s fascinating chiral substances,scientists have synthesized chiral materials with various types and functions.Among them,circularly polarized luminescent（CPL）materials have attracted more and more research interests among scientists due to their unique chiral photophysical properties and extensive applications in information spin encryption,3D optical display,biological imaging and other fields.How to efficiently prepare CPL materials with excellent properties has always been a hot and difficult research topic.As a topological structure,helical is essentially chiral,which makes helical small molecules,polymers and even supramolecular assembly exhibit strong optical activity.Among them,chiral helical polymer has become an important branch of chiral materials and CPL materials because of its rich variety,easy processing,high stability and controllable properties.Chirality and luminescence are the key factors to realize the CPL properties of materials.In this thesis,based on helical substituted polyacetylene,the two elements of chirality and luminescence were studied respectively to prepare various kinds of CPL materials with high luminescence.Specific research contents are as follows:（1）We prepared small molecule/polymer system CPL composite films.A series of chiral fluorescent small molecules without CPL activity were synthesized first.By using the unique dynamic helical structure of chiral helical polyacetylene,the two components,i.e.,chiral fluorescent small molecule and helical polymer,achieved effective chirality transfer and chirality amplification in the process of casting into film,finally realizing the CPL emission of material system.Based on these CPL composite films,red CPL emission of from the added fluorophore is further achieved simply and efficiently by circularly polarized fluorescence energy transfer（CPF-ET）strategy.In this study,chiral fluorescent small molecules and achiral helical polyacetylenes are combined to proposed a novel design idea for CPL materials,which has a certain universality.Moreover,the innovative use of helical polyacetylene as a"chiral amplifier"has greatly improved the chirality and CPL performance of material system.The polymers and small molecules can achieve the synergy effect between the performance without any additional chemical reaction,and realized the CPL emission of the material system.（2）The carbon dots/chiral helical polymer bilayer composite films with circularly polarized fluorescence（CPF）and circularly polarized room temperature phosphorescence（CPRTP）were prepared by spinning coating,and the luminescence asymmetry factor was up to-1.4×10-1 and-1.2×10-2,respectively.Among them,the carbon dots provide FL and RTP emission,and the chiral helical polymer provides necessary optical activity.The two components exist in the two layers respectively,without considering the chiral transfer between components,and the strong CPL emission can be achieved by simple bonding between the single-films.Through bidirectional characterization and analysis of CD and CPL spectra of bilayer films,we found that the CPL generation mechanism in this case is different under varying test channels,and thus proposed the"circular polarization excitation"mechanism.In this mechanism,the chiral helical polymer can polarize the excited light so that it can directly excite the carbon dots to emit CPF.Moreover,by introducing red fluorophore into the composite film,we realized white CPL emission,and carried out simple application of multiple information display,demonstrating the application potential of this material in related fields. |
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