Mechanochemical Transition from a Hydrogen-Bonded Organic Framework to Covalent Organic Frameworks

We reported the directed structural transformation ofa hydrogen-bondedorganic framework (HOF) to covalent organic frameworks (COFs) viaa mechanochemical drive for the first time. The X-ray single crystalstructure confirmed that the hydrogen bonds afford a 3-connected aminebuilding unit forming a HOF, namely, HOF-TPPA, with a hcb topology. The topological similarity between HOF and the targetedCOFs facilitates the transition from HOF-TPPA to COFs (isotopologicalCOF-TPPA-1, COF-TPPA-2, and COF-TPPA-3) under the mechanical grinding.Furthermore, the as-synthesized COFs exhibited broad light absorption,superior chemical stability, and excellent photocatalytic hydrogenevolution performance (45.429 mmol g(-1) h(-1)). This work not only produced a series of novel large-channel two-dimensionalmulticomponent COFs but also provided new guidance for the green andefficient synthesis, as well as the functionalized applications ofCOFs.