Rationally fabricating 3D porphyrinic covalent organic frameworks with scu topology as highly efficient photocatalysts

The exploration of highly crystalline three-dimensional (3D) covalent organic frameworks (COFs) with new topologies remains challenging. In this work, we rationally designed and synthesized two highly crystalline 3D COFs, constructed by an octatopic linker and porphyrin-based tetratopic linkers through an [8 + 4] approach. The COF structures were successfully determined as non-interpenetrated scu topology using the continuous rotation electron diffraction (cRED) technique and structural simulation. The scu network was further verified by both high-resolution transmission electron microscopy (TEM) and pore size distribution based on N2 sorption isotherms. Due to the exposed catalytic porphyrin sites, good photoelectric activity, and high structure robustness, these COFs can serve as highly efficient heterogeneous photocatalysts for various reactions, including oxidative amine coupling and cycloaddition reactions between tertiary aniline and maleimide, with a broad substrate scope (22 examples). This work enriches the topological varieties of 3D COFs and provides a class of highly efficient photocatalysts.