Clustering‐Triggered Emission Liquid Crystalline Polymer Bearing Cholesterol: Tunable Circularly Polarized Luminescence and Room‐Temperature Phosphorescence

Abstract

Circularly polarized luminescence (CPL) materials with clustering‐triggered emission (CTE) characteristic have gradually attracted attention for their unique photo‐physical properties. However, the majority of reported clusteroluminogens lack chirality and exhibit heterogeneity, making it challenging to achieve a well‐defined helical structure necessary for efficient CPL with high dissymmetry factor (glum). In this article, we constructed chiral liquid crystals to obtain CTE based CPL materials with high glum values. We designed and synthesized side chain liquid crystal polymer PM6Chol bearing cholesterol clusteroluminogens. PM6Chol coated film and PM6Chol thermal treated film were also successfully prepared by different film‐forming methods. Both the two films inherited the CTE characteristic of cholesterol and showed excitation wavelength‐dependent luminescent behavior. While, the two polymer films exhibited different liquid crystal phase structures, with PM6Chol coated film being a chiral bilayer smectic C phase and PM6Chol thermal treated film being an achiral bilayer smectic A phase. Attributed to helical arrangement of cholesterol, PM6Chol coated film emitted efficient CPL with glum values up to 1.0 × 10−1. For PM6Chol thermal treated film, no CPL signal was detected due to the absence of helical structure. However, it showed obvious room temperature phosphorescence with 2.0 s afterglow and 23.9 ms lifetime.This article is protected by copyright. All rights reserved

Multicolor‐Tunable and Time‐Dependent Circularly Polarized Room‐Temperature Phosphorescence from Liquid Crystal Copolymers

“…PM6Chol shows clustering‐triggered emission characteristic and also exhibits AIE property. [ 40 ] The photo‐physical properties of copolymers during aggregation process were also characterized and this article only used copolymer Poly(MDFM6C(0.13)‐co‐M6Chol(0.87)) as an example for detailed characterization. Poly(MDFM6C(0.13)‐co‐M6Chol(0.87)) shows concentration enhanced luminescence characteristics and the emission intensity increases with the increase of its concentration (Figure S8a, Supporting Information).…”

“…The delayed emission spectra of polymer films were also characterized. PM6Chol exhibits dual phosphorescence emissions centered at 450 and 480 nm, and their lifetimes are 23.9 and 9.7 ms. [ 40 ] PMDFM6C film also exhibits long afterglow luminescence characteristic. As presented in Figure , an obvious phosphorescence emission peak at ≈550 nm featuring a lifetime of ≈476.8 ms is observed.…”

“…The detailed synthesis methods are provided in Supporting Information. The synthetic method of M6Chol had been reported in the previous research, [ 40 ] and the detailed synthetic method will not be provided in this article.…”