Targeted construction of a three-dimensional metal covalent organic framework with spn topology for photocatalytic hydrogen peroxide production

To enrich the topology of three-dimensional covalent organic frameworks (3D COFs) is an appealing challenge. Till now, only 20 types of topologies have been achieved in 3D COFs because of the limited polyhedral building blocks. Herein, we report the first 3D titanium-based COF with spn topology (TiCOF-spn) through [6 + 3] imine condensation of a Ti(IV) complex with six aldehyde groups positioned in a trigonal antiprismatic arrangement and a planar triazine-based amine connector. Interestingly, TiCOF-spn contains two kinds of pores, that is, the linking of the tetrahedral cages by sharing vertices forms the truncated tetrahedral cages. By integrating the crystalline porous framework, photoactive titanium center and triazine component, TiCOF-spn shows strong visible light absorption and efficient photocatalytic activity for producing H2O2 (489.94 mu mol g(-1)h(-1)). This work expands the topology of the 3D COFs family and pioneers the application of metal-containing COFs in solar energy conversion.