Covalent organic frameworks (COFs) are dynamic covalent porous organic materials synthesized from molecular organic building blocks. However, the chemical linkages used to construct COFs are limited by the dynamic bond formation needed to ensure crystallinity. Thus, there is a continual search for new, chemically stable linkages that tailor both the chemical properties and topologies of COFs. As opposed to electrophilic linkages used to construct COFs, nucleophilic linkages that can react with electron-deficient species are rare. Here we report the synthesis of picolinaldehyde-derived imine-linked COFs that can be transformed into imidazopyridinium-linked COFs (IP-COFs) with a Lieb-like lattice. IP-COFs serve as precursors to ambivalent N-heterocyclic carbenes that can dissociate disulfide bonds to form carbon–sulfur bonds. IP-COFs exhibit a vastly improved sulfur redox chemistry when used as cathode materials in lithium–sulfur batteries, as they achieve a rate performance of 540 mAh g⁻¹ (10 C) and a high areal capacity of 6.2 mAh cm⁻² with a high sulfur loading of 9 mg cm⁻² and a low electrolyte-to-sulfur ratio of 6 µl mg⁻¹. In addition, the ionicity of the linkages enables the cleavage of IP-COFs into highly crystalline flakes with well-defined fringes, as resolved by atomic force microscopy and transmission electron microscopy.

共价有机骨架（COFs）是由分子有机结构单元合成的动态共价多孔有机材料。然而，用于构建 COF 的化学键受到确保结晶度所需的动态键形成的限制。因此，需要不断寻找新的、化学稳定的连接，以定制 COF 的化学性质和拓扑结构。与用于构建 COF 的亲电键不同，可以与缺电子物质反应的亲核键很少见。在这里，我们报告了吡啶甲醛衍生的亚胺连接 COF 的合成，该 COF 可以转化为具有 Lieb 样晶格的咪唑并吡啶鎓连接 COF (IP-COF)。IP-COFs 作为二价 N-杂环卡宾的前体，可以解离二硫键形成碳-硫键。^-1 (10 C) 和 6.2 mAh cm ^{-2的高面积容量和 9 mg cm -2}的高硫负载量和 6 µl mg ^-1的低电解质硫比。此外，通过原子力显微镜和透射电子显微镜可以解决，连接的离子性使 IP-COF 能够裂解成具有明确边缘的高度结晶薄片。