Chen Xinmeng, Zhang Siwei, Jiang Yefei, He Guiying, Zhang Minjie, Wang Jin, Deng Zihao, Wang Haoran, Lam Jacky W Y, Hu Lianrui, Zhong Tang Ben
Department of Chemistry, and the Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China.
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, China.
Angew Chem Int Ed Engl. 2024 May 6;63(19):e202402175. doi: 10.1002/anie.202402175. Epub 2024 Apr 8.
Schiff bases are a crucial component in various functional materials but often exhibit non-emissive behavior which significantly limits their potential applications as luminescent materials. However, traditional approaches to convert them into aggregate emitters often require intricate molecular design, tedious synthesis, and significant time and resource consumption. Herein, we present a cocrystallization-induced emission strategy that can transform non-emissive (hetero)aryl-substituted Schiff bases into green-yellow to yellow aggregate emitters via even simple grinding of a mixture of Schiff bases and 1,2,4,5-tetracyanobenzene (TCB) mixtures. The combined experimental and theoretical analysis revealed that the cocrystallization inhibits the C=N isomerization and promotes face-to-face π-π interaction, which restricts access to both the dark state and canonical intersection to ultimately induce emission. Furthermore, the induced emission enables the observation of solid-state molecular diffusion through fluorescence signals, advancing white light emission diodes, and notably, solution-processed organic light-emitting diodes based on cocrystal for the first time. This study not only highlights the potential of developing new C=N structural motifs for AIEgens but also could boost advancements in related structure motifs like C=C and N=N.
席夫碱是各种功能材料中的关键成分，但常常表现出非发光行为，这极大地限制了它们作为发光材料的潜在应用。然而，将它们转化为聚集发光体的传统方法通常需要复杂的分子设计、繁琐的合成过程，以及大量的时间和资源消耗。在此，我们提出了一种共结晶诱导发光策略，通过简单研磨席夫碱与1,2,4,5-四氰基苯（TCB）的混合物，就能将非发光的（杂）芳基取代席夫碱转化为黄绿色至黄色的聚集发光体。结合实验和理论分析表明，共结晶抑制了C=N异构化，并促进了面对面的π-π相互作用，从而限制了进入暗态和规范交叉点的机会，最终诱导发光。此外，诱导发光使得通过荧光信号观察固态分子扩散成为可能，推动了白色发光二极管的发展，值得注意的是，首次实现了基于共晶的溶液处理有机发光二极管。这项研究不仅突出了开发用于聚集诱导发光材料的新型C=N结构基序的潜力，还可能推动C=C和N=N等相关结构基序的发展。
