Ji Lukang, Li Jinqi, Meng Tianzi, Li Zujian, Zhu Huajie, Ouyang Guanghui, Liu Minghua
Beijing National Laboratory of Molecular Sciences and CAS Key Laboratory of Colloid, Interface and Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, North First Street 2, Zhongguancun, Beijing, 100190, China.
School of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei Province, 050018, China.
Small Methods. 2025 Jan;9(1):e2400824. doi: 10.1002/smtd.202400824. Epub 2024 Nov 3.
The realization of persistent luminescence and in particular circularly polarized luminescence (CPL) of organic radicals remains a challenge due to their sensitivity to oxygen at ambient conditions and elusive excited state chirality control. Here, it is reported that UV-irradiation on a supramolecular gel from a chiral triarylamine derivative, TPA-Ala, led to the formation of luminescent radicals with bright CPL. TPA-Ala can form an organogel in chloroform with blue emission and supramolecular chirality as demonstrated by both CD and CPL signals. Upon UV 365 nm irradiation, an emission color change from blue to cyan is observed due to the formation of photo-induced radicals. Interestingly, it is found that the supramolecular gel radicals showed stable luminescence with a lifetime ≈ 10 days in dark environments and inverted CPL, which represents a scarce example with persistent CPL from doublet-state due to oxygen isolation ability of the gel network. Furthermore, doping a guest dye, Rhodamine B (RhB), into the supramolecular gel (RhB/TPA-Ala = 30% in molar ratio) successfully obtained a transient white-light CPL through the superposition of photo-induced radical and guest dye emissions. This work provides a useful methodology for the fabrication of radical-based CPL materials via a supramolecular assembly approach.
由于有机自由基在环境条件下对氧气敏感且难以控制激发态手性，实现其持续发光，尤其是圆偏振发光（CPL）仍然是一个挑战。在此，有报道称对手性三芳基胺衍生物TPA-Ala形成的超分子凝胶进行紫外线照射，会导致形成具有明亮CPL的发光自由基。TPA-Ala能在氯仿中形成具有蓝色发射和超分子手性的有机凝胶，这通过CD和CPL信号得以证明。在365 nm紫外线照射下，由于光诱导自由基的形成，观察到发射颜色从蓝色变为青色。有趣的是，发现超分子凝胶自由基在黑暗环境中显示出稳定的发光，寿命约为10天，并且具有反向CPL，这是由于凝胶网络的氧气隔离能力而导致的来自双重态的持续CPL的罕见例子。此外，将客体染料罗丹明B（RhB）掺杂到超分子凝胶中（摩尔比RhB/TPA-Ala = 30%），通过光诱导自由基和客体染料发射的叠加成功获得了瞬态白光CPL。这项工作为通过超分子组装方法制备基于自由基的CPL材料提供了一种有用的方法。
