Covalent organic frameworks (COFs) are porous crystalline framework materials that are amenable to design and functionalization. Herein, an aggregation-induced emission monomer, 4,4′,4″,4‴-(ethene-1,1,2,2-tetrayl)tetrabenzaldehyde (ETB), is used as a building block to react with an olefin linkage to construct sp² carbon-conjugated COFs for exploring their electrochemiluminescence (ECL). The ECL efficiency of ETB immobilized in the COF framework is significantly improved by nearly 100 times without any exogenous co-reactants in aqueous solution, compared with the monomer aggregation state. This framework-induced ECL (FIECL) is attributed to the long-range orderly arrangement of COFs confining the rotation of ETB in the π-conjugated backbone, thereby effectively facilitating the electronic transfer for excited-state generation. Density functional theory calculations prove that the COFs have lower energy bands compared with the monomers, so that electron transfer can be accelerated within frameworks to obtain a much stronger FIECL signal. This FIECL strategy will greatly expand the broad application prospects of COFs in organic optoelectronics.

中文翻译：

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用于骨架诱导电化学发光的 sp2 碳共轭共价有机骨架的构建

共价有机骨架 (COF) 是易于设计和功能化的多孔结晶骨架材料。在此，聚集诱导发光单体 4,4',4",4‴-(ethene-1,1,2,2-tetrabenzaldehyde (ETB)) 用作结构单元与烯烃键反应构造 sp ²碳共轭 COF 用于探索其电化学发光 (ECL)。与单体聚集状态相比，固定在COF框架中的ETB的ECL效率显着提高了近100倍，水溶液中没有任何外源共反应物。这种框架诱导的 ECL（FIECL）归因于 COF 的长程有序排列，限制了 ETB 在 π 共轭骨架中的旋转，从而有效地促进了激发态生成的电子转移。密度泛函理论计算证明，与单体相比，COFs 具有更低的能带，因此可以加速框架内的电子转移以获得更强的 FIECL 信号。这一 FIECL 策略将极大地拓展 COFs 在有机光电子领域的广阔应用前景。