De Novo Design and Facile Synthesis of 2D Covalent Organic Frameworks: A Two-in-One Strategy

We herein develop a two-in-one molecular design strategy for facile synthesis of 2D imine based covalent organic frameworks (COFs). The integration of two different functional groups (i.e., formyl and amino groups) in one simple pyrene molecule affords a bifunctional building block: 1,6-bis­(4-formylphenyl)-3,8-bis­(4-aminophenyl)­pyrene (BFBAPy). Highly crystalline and porous Py-COFs can be easily prepared by the self-condensation of BFBAPy in various solvents, such as CH2Cl2, CHCl3, tetrahydrofuran, methanol, ethanol, acetonitrile, and dimethylacetamide, etc. The current work, to the best of our knowledge, is a rare case of COF synthesis that exhibits excellent solvent adaptability. Highly crystalline Py-COF thin films have been facilely fabricated on various substrates and exhibit potential applications in hole transporting layers for perovskite solar cells. Furthermore, the versatility of this two-in-one strategy was also verified by two additional examples. The current work dramatically reduces the difficulty of COF synthesis, and such two-in-one strategy is anticipated to be applicable for the synthesis of other COFs constructed by different building blocks and linkages.本研究开发了一种一体式分子设计策略，可便捷合成基于亚胺键的二维共价有机框架（Covalent Organic Frameworks, COFs）。将甲酰基与氨基两种不同官能团整合至单一芘分子中，可得到双功能构筑基元：1,6-双(4-甲酰基苯基)-3,8-双(4-氨基苯基)芘（BFBAPy）。通过BFBAPy在多种溶剂（如二氯甲烷、三氯甲烷、四氢呋喃、甲醇、乙醇、乙腈及二甲基乙酰胺等）中发生自缩合反应，可简便制备得到高结晶性、高孔隙率的Py-COFs。据我们所知，本研究是为数不多的具备优异溶剂适应性的COFs合成案例之一。我们可在多种基底上便捷制备高结晶性Py-COF薄膜，该薄膜有望应用于钙钛矿太阳能电池的空穴传输层。此外，通过另外两个实例进一步验证了该一体式策略的普适性。本研究大幅降低了COFs的合成难度，预计该一体式策略可推广应用于其他由不同构筑基元与连接方式构建的共价有机框架的合成。