Synthesis and Properties of Mesogen-Jacketed Liquid Crystal Copolymers with Long-Lived Circularly Polarized Room-Temperature Phosphorescence

Abstract

Circularly polarized phosphorescence (CPP) materials, integrating the advantages of phosphorescence with circularly polarized luminescence, show wide applications in many fields. However, designing and preparing pure organic CPP materials remain challenging, as ensuring the stability of triplet excitons at room temperature while achieving chiral transfer from chiral structures to achiral chromophores is difficult. Herein, we propose a strategy to harness the structural features of mesogen-jacketed liquid crystal polymers (MJLCPs) for CPP material construction. A chiral monomer MJ0Chol and a phosphorescent monomer MJ0DFM are polymerized to prepare the homopolymers PMJ0Chol and PMJ0DFM and copolymers DFM(x)-Chol(y). The phosphorescence lifetime is effectively enhanced by the "jacketing" effect of MJLCPs, and the circularly polarized luminescence is activated through the construction of a chiral helical columnar phase. With the content of the MJ0DFM component increasing, the lifetime of copolymers gradually improves. Meanwhile, the |g lum | values of the samples exhibit an initial increase followed by a decrease with an increasing cholesterol content. DFM(0.6)-Chol(0.4) shows the highest g lum values for both fluorescence and phosphorescence, reaching −4.4 × 10 −3 and −7.1 × 10 −3 , respectively. Meanwhile, the phosphorescence lifetime can be achieved at 252 ms.