Synthesis And Properties Of O-Carborane-Based Circularly Polarized Luminescence Materials

Circularly polarized luminescence（CPL）is a unique optical property exhibited by chiral luminescent materials,which has a wide range of applications in various fields such as 3D display,spintronics,and information encryption.The asymmetry factor(g_lum)is a parameter used to measure the degree of polarization of circularly polarized luminescence materials,which is an important indicator of the excellent performance of such materials.In recent years,the study of circularly polarized luminescence materials has received more and more attention and has become a popular research area.The free-rotation property of carborane groups makes them a material of great interest with superior optoelectronic properties in the field of organic electronics.However,the number of carborane-based circularly polarized luminescence materials is currently small and their asymmetry factor g_lum is usually only between 10^-3 and 10^-4.This thesis aims to investigate how to obtain efficient CPL active materials and enhance the key problem of asymmetry factor g_lum,we designed and synthesized a series of carborane-based circularly polarized luminescence materials,the main research content and innovation points are as follows:1.Using the chiral transfer strategy,we designed and synthesized pyridine-containing non-chiral molecules based on carborane,the rotation of carborane can regulate the ratio of magnetic to electrical leap dipole moment,which can achieve the purpose of enhancing the asymmetry factor g_lum.By selecting suitable chiral molecules and probing the induction of chiral molecules to non-chiral molecules,the non-chiral molecules are combined with chiral template reagents,and the chiral information is effectively transferred to the non-chiral molecules through hydrogen bonding,which significantly improves the asymmetry factor g_lum by an order of magnitude up to 10^-2,which is better than the current average value.This provides useful ideas for the design and preparation of higher performance circularly polarized luminescence materials.2.A series of thermal delayed fluorescent materials with superior performance has been designed and synthesized based on carborane and dimethylfluorene,benzene ring and triazine as the building blocks.The three-dimensional spatial structure of carborane molecules and the rigid structure of triazine molecules are combined,and the stability of the molecules is greatly improved by taking dimethylfluorene and benzene ring molecules as the main body.The strongπ-πinteractions between the triazine functional group molecules enable the formation of stable excited state structures and increase the CPL activity of the excited state structures as well as the value of the asymmetry factor g_lum.A series of performance characterization tests such as thermodynamic properties,electrochemical properties,AIE properties,fluorescence lifetime and quantum efficiency,and circularly polarized fluorescence spectra was performed on the materials.The results show that the materials have good thermal stability and electrochemical properties,significant AIE effect,high fluorescence quantum efficiency and asymmetry factor g_lum of order 10^-2 and 10^-3,which have good potential applications in optoelectronic devices.The work in this chapter provides a new strategy for the subsequent preparation of structurally stable and thermally stable circularly polarized luminescence materials.