Inverted and Amplified Circularly Polarized Luminescence Behavior Originated from Structure–Activity Regulation of Achiral Pyrene-Based Polymers in Chiral Coassemblies

The design of excellent circularly polarized luminescence (CPL) materials with a large luminescence dissymmetry factor (glum) remains a great challenge. In this paper, we chose two achiral conjugated pyrene-based main-chain polymers (BP-1 and BP-2) with different substitution positions (1,6-positions of the pyrene rings for BP-1 and 2,7-positions of the pyrene rings for BP-2) and a chiral binaphthyl-based inducer (S/R-D) with a bridged alkyl chain to construct chiral coassemblies through an intermolecular chirality induction mechanism. Interestingly, after the thermal annealing treatment, the resulting coassemblies S/R-D-BP-2 could emit inverted and amplified CPL signals compared with S/R-D-BP-1. Most significantly, the maximum |glum| value of (S/R-D)0.2-(BP-2)0.8 in a spin-coated film was up to 0.71 (λem = 428 nm, QY = 44.8%) at a 220 nm thickness, which was about 6-fold that of (S/R-D)0.1-(BP-1)0.9 (|glum| = 0.12, λem = 451 nm, QY = 37.6%). The excellent glum value of (S/R-D)0.2-(BP-2)0.8 was due to the formation of regular and ordered helical nanofibers through the strong intermolecular π–π stacking interactions. This work provides a creative approach to tune the CPL emission amplification behaviors by chiral coassembly from achiral pyrene-based main-chain polymers.