基于联萘酚骨架的新型圆偏振发光材料的合成及性能探究

A series of chiral luminescent molecules based on binaphthol skeleton and having electron donor diarylamine (NN), electron donor/acceptor diarylamine and diarylboron (BN), electron donor/acceptor diarylamine and cyano (4N2CN) were synthesized. The properties of several molecules were compared by introducing different acceptor groups and extended molecular chiral skeletons. Compounds BN and 4N2CN exhibit significant thermochromic shift of the emission due to the intramolecular charge transfer (ICT) character. The emission wavelength was linearly enhanced with a high correlation coefficient of 0.991 for BN between 345 K and 150 K, 0.996 for 4N2CN between 345 K and 180 K. Furthermore, a fully reversible emission response was corroborated by an excellent fatigue resistance without emission degradation upon its exposure to 5 cycles of temperature change over a range of 195 K and 165 K for BN and 4N2CN. Optical resolution of the racemic mixtures have been performed for further investigation. The initial injection of these molecules into a chiral high performance liquid chromatography (HPLC) with a Daicel Chiralpak IA column resulted in two separated peaks with 1∶1 area. We try to further explore their chiral optical properties, including circular dichroism (CD) and circular polarized luminescence (CPL). The signal of CD indicates their chiral properties in the ground state. However, the difference of CPL signals of these compounds shows that the difference of group and skeleton will affect the chiral properties of molecules in the excited state. BN showed high brightness and Φ_L of BN in solution can reach 0.99. In addition, 4N2CN exhibit aggregation-induced emission (AIE) properties in polar solvent and dynamic light scattering (DLS) was employed to monitor the process of aggregate formation. Based on this, we believe that the skeleton expansion and the introduction of electron-donor/acceptor groups make 4N2CN have unique photophysical properties. This work not only expands the family of chiral optical structures but also provides an idea to enhance the CPL signal and glum values.