Li Yang, Chen Yihan, Li Hang, Liu Chao, Li Lulu, Quan Yiwu, Cheng Yixiang
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Key Laboratory of High Performance Polymer Material and Technology of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Angew Chem Int Ed Engl. 2023 Nov 13;62(46):e202312159. doi: 10.1002/anie.202312159. Epub 2023 Oct 12.
It is noteworthy that cholesteric liquid crystal (CLC) platforms have been witnessed in high-performance circularly polarized luminescence (CPL) behaviors through the highly organized chiral co-assembled arrangement of achiral dyes. However, most CPL-active design strategies are closely relative to the helix co-assembly structure of CLC rather than achiral dyes. Herein, we developed an intriguing regulation strategy for CPL-active CLC materials. They were regulated using the orientational order parameter (S ) of achiral dichroic dyes as an incisive probe for the order arrangement degree of achiral dyes in CLC media. The I-shaped phenothiazine derivative PHECN dye (S =0.30) emitted a strong CPL signal (|g |=0.47). In contrast, the T-shaped derivative (PHEBen) dye (S =0.09) showed a weak circular polarization level (|g |=0.07) at similar CLC textures. Most interestingly, this kind of dichroic PHECN dye with a higher S could greatly improve the contrast ratio of CPL (Δg =0.47) and emission intensity (ΔFL=46.0 %) at direct-current electric field compared with the T-shaped PHEBen (Δg =0.07 and ΔFL=1.0 %) in CLC. This work demonstrates that an induced CPL emission can be mediated using achiral dichroic dye, which will open a new avenue for developing excellent CPL-active display materials.
值得注意的是，通过非手性染料高度有序的手性共组装排列，胆甾相液晶（CLC）平台已展现出高性能圆偏振发光（CPL）行为。然而，大多数具有CPL活性的设计策略与CLC的螺旋共组装结构密切相关，而非与非手性染料相关。在此，我们开发了一种用于具有CPL活性的CLC材料的有趣调控策略。我们使用非手性二色性染料的取向序参数（S）作为CLC介质中非手性染料有序排列程度的敏锐探针来对它们进行调控。I形吩噻嗪衍生物PHECN染料（S = 0.30）发出强烈的CPL信号（|g| = 0.47）。相比之下，在类似的CLC织构下，T形衍生物（PHEBen）染料（S = 0.09）显示出较弱的圆偏振水平（|g| = 0.07）。最有趣的是，与CLC中的T形PHEBen（Δg = 0.07和ΔFL = 1.0 %）相比，这种具有较高S的二色性PHECN染料在直流电场下可极大地提高CPL的对比度（Δg = 0.47）和发射强度（ΔFL = 46.0 %）。这项工作表明，可以使用非手性二色性染料介导诱导CPL发射，这将为开发优异的具有CPL活性的显示材料开辟一条新途径。
