Cholesteric liquid crystals based on triphenylene bridged binaphthyl derivatives: Mesomorphism, optical properties and circular polarization luminescence properties

Circularly Polarized Luminescence (CPL) materials have garnered significant attention due to their potential applications in chiral light-emitting transistors, optical data storage, spintronic communications, and 3D displays. The self-assembly of cholesteric liquid crystals (CLCs) is an effective strategy to achieve high-quality CPL materials. The combination of chiral binaphthyl with discotic liquid crystal molecules is undoubtedly a very innovative design idea. In this study, we synthesized a series of the dinaphthotriphenyl derivatives R/S-DTPBn (n = 4, 6, 8, 10) via the Suzuki-Miyaura cross-coupling reaction. S-DTPB10 exhibited blue fluorescence and an exceptionally high absolute quantum yield of 76 % in solution. Subsequently, the R/S-DTPBn as chiral additives were incorporated at a 20 % mass ratio into the nematic liquid crystal E7, resulting in the formation of binary cholesteric liquid crystals R/S-DTPBn-E7. These binary cholesteric liquid crystals were room temperature liquid crystals and exhibited wide mesophase ranges. Moreover, the circular dichroism (CD) and circularly polarized luminescence (CPL) of these binary cholesteric liquid crystals displayed trends of amplified chiroptical signals, with the considerable luminescence dissymmetry factor (glum) values of up to 0.157. This research provides new insights into the design of CPL liquid crystalline materials with high glum values.