Synthesis And Properties Of AIE-active Polymer-based Circularly Polarized Luminescence Materials

Circularly polarized luminescence(CPL)is seen as one special chiroptical property for some chiral fluorescence system.Normally,CPL has been mainly exploited not only to investigate structural information of the excited state of a chiral molecule,but also to play an important role in the potential applications in information storage,3D optical display and photoelectric devices.Early research demonstrated that compared to organic small molecules,polymers have some obvious advantages in fabricating photoelectric devices due to their easy fabrication and low cost and greatly amplifying the fluorescence response signals through facile energy migration along the polymer backbone upon the light excitations.In this dissertation,the studies focused on the synthesis of AIE-active CPL materials incorporating tetraphenylethene(TPE)as aggregation-induced enhancement group and some chiral sources(BINOL and BINAM),and their CPL properties in molecular dispersal and aggregated states.The main works of this dissertation are as follows:1.Two chiral conjugated polymer enantiomers incorporating 1,1'-binaphythyl as the chiral source and tetraphenylethene(TPE)as chromophore have be synthesized by click polymerization reaction.It is noteworthy that TPE plays the role of aggregation-induced enhancement group.The target enantiomers show strong aggregation-induced circularly polarized luminescence(AICPL)emission signals in the aggregate and cast-spin film,and the dissymmetry factors dlum can be up to 6.97 ×10-3 and 1.45 ×10-2,respectively.The SEM images further show that AICPL response behavior of the polymers can be attributed to the formation of the supramolecular self-assembled helical nanowires in the aggregation state.2.We synthesize two AIE-active chiral polymers by the addition reaction of isothiocyanate and amino group,incorporating chiral 2,2'-binaphthyldiamine as the chiral source and the tetraphenylethene(TPE)derivative as chromophore.By investigating their optical activity characteristics,we find that the intensity of fluorescence emission can be strenghthened up to 15 times in the mixed solution of water and tetrahydrofuran.The target polymers can effectively transfer the chirality to the main-chain backbone and induce the strong circular dichroism response(|gabs| value of 0.0044).The futher study of their circularly polarized luminescence response shows that the corresponding glum values in the aggregated state and in the spin-coated thin film are 2.71 × 10-3 and 7.69 × 10-3 respectively,strongly supporting the fact that the chirality from BINAM has been succssfully transferred to the polymer backbone.