Synthesis And Properties Of AIE-active 1,8-naphthalimide With Circularly Polarized Luminescence

In the past few decades, circularly polarized luminescence (CPL) material as the selective emission of left- and right-handed circularly polarized light from chiral chromophore system have attracted much attention on the organic materials. Normally, CPL has been mainly used to investigate structural information on the excited state of a chiral molecule. As is known to all, it is quite difficult to produce high level of CPL for simple chiral organic molecules (small, non-polymeric, non-aggregated). Therefore, developing the design strategy of excellent CPL materials of chiral organic chromophores is of great significance. In this dissertation, the studies focused on the synthesis of CPL materials based on 1,8-naphthalimide, their CPL properties in solution and aggregated states, and the influences on the CPL property. The main works of this dissertation are as follows:1. We synthesized four chiral binaphthyl-based molecules incorporating the AIE-active 1,8-naphthalimide groups. In these molecules, two moieties have different functions:i) binaphthyl moiety as the chiral source;ii) 1,8-naphthalimide as the acting chromophore and the AIE-active group. Most interestingly, reverse CPL signals of both R/S 2-1 and R/S 2-2 could be observed from THF solution to aggregation. The theoretical calculations demonstrate that the opposite signals of CPL spectra could be attributed to two types of stable conformations of R/S 2-1 and R/S 2-2 with different dihedral angles of the binaphthyl units in THF solution and THF-water mixed solvents.2. We synthesized four chiral 1,2-DACH-based molecules incorporating the 1,8-naphthalimide chromophore group as excimer emission molecule. Interestingly, R/S 3-2 can emit circularly polarized fluorescence at 470 nm induced by the excimer emission of the 1,8-naphthalimide chromophore group, and the glum values can reach as high as about ±3.67×10-2 in MeOH solution. Mostly important, the compounds R/S 3-2 and R/S 3-4 can exhibit reversal CPL signals from solution to aggregation due to orderly aggregation state.