Three-Dimensional Covalent Organic Frameworks with she Topology.

Reticular chemistry allows the control of crystalline frameworks at atomic precision according to the predesigned topological structures. However, only a limited number of topological structures of three-dimensional (3D) covalent organic frameworks (COFs) have been established. In this work, we developed a series of 3D COFs with an unprecedented she topology, which were constructed with D 3d - and D 4h -symmetric building blocks. The resulting COFs crystallize in a space group of Im 3̅ m , in which each D 3d unit connects with six D 4h units to form a noninterpenetrated network with a uniform pore size of 2.0 nm. In addition, these COFs exhibited high crystallinity, excellent porosity, and good chemical and thermal stability. The crystalline structures, composition, and physicochemical properties of these networks were unambiguously characterized. Notably, the inbuilt porphyrin units render these COFs as efficient catalysts for photoredox C-C bond forming and photocatalytic carbon dioxide reduction reactions. Thus, this work constitutes a new approach for the construction of 3D she -net COFs and also enhances the structural diversity and complexity of COFs.