Synthesis And Properties Of AIE-active Materials Based On Chiral BINOL With Circularly Polarized Luminescence

Circularly polarized luminescence (CPL) is special chiroptical property for some chiral chromophores. Recently, CPL has attracted great interest not only due to the valuable information on the chirality of the electronic excited states, but also its potential applications in display devices, optical storage and processing systems, sensors and so on. In this dissertation, the studies focused on the synthesis of aggregation-induced emission (AIE) active conjugated CPL materials based on chiral BINOL via palladium-catalyzed coupling reactions, their CPL properties in molecular dispersal and aggregated states, and the influences on the CPL property. The main works of this dissertation are as follows:1. Four main-chain chirality conjugated polymers with different linked positions and bonds were synthesized from AIE-active chromophore, tetraphenylethene (TPE), and chiral BINOL by palladium-catalyzed coupling reactions. Then we studied their chiroptical property both in molecular dispersal and aggregated states. The results demonstrate that the four polymers show obvious AIE feature. The polymer linked with tri-bond at 3,3’-positions of BINOL shows helical main-chain in solution, and it could self-assemble into helical nanofibers during aggregation. The formation of chiral nanostructures makes the polymer produce aggregation-induced CPL signals. However, other three polymers with different linked positions and bonds do not have chiral main-chain structures in solution or nanostructures in aggregation. Therefore, the linked position and bonds play important roles for the chiroptical properties of these polymers.2. Achiral BODIPY dyes could form induced chirality by linked with chiral BINOL via covalent bond. Then the induced chirality structure and TPE were used for preparing main-chain chirality polymers which had enantiomeric repeated units. And the optical properties of these two polymers were studied both in solution and aggregation. The results demonstrate that the polymers have aggregation-induced enhanced emission (AIEE) feature. Two polymers show chiroptical property resulting from the introduction of induced chirality 0-BODIPY structure. The two polymers show CPL signals both in solution and aggregation. However, the small Stokes’shifts of them obviously affect their CPL properties.3. We synthesized two enantiomers based on TPE and induced chirality OBODIPY chromophores by Sonogashira coupling reaction, and studied their optical property both in solution and aggregation. The results demonstrate that the compounds have obvious AIE feature and chiroptical property both in solution and aggregation. However, the small Stokes’shifts affect their CPL properties. As shown in UV-vis and fluorescence spectra, there is overlap between emission spectra of TPE and absorption spectra of O-BODIPY moiety. Therefore, through-bond intramolecular energy transfer (IET) could occur from TPE to BDIPY part in the compounds. Then we used the IET to study their CPL signals. The results show that the CPL signals of two compounds improved when used IET to form large Stokes’shifts. In this case, the two enantiomers showed red-color mirror-image CPL signals, which did not have obvious changes during aggregation. These results of chiroptical properties indicate that the chirality of electronic ground and excited states of the molecules is stable and independent of aggregation.