Stepwise Synthesis of Robust Metal–Organic Frameworks via Postsynthetic Metathesis and Oxidation of Metal Nodes in a Single-Crystal to Single-Crystal Transformation

Utilizing PCN-426-Mg as a template, two robust metal-organic
frameworks (MOFs), PCN-426-Fe­(III) and PCN-426-Cr­(III), have been synthesized through a strategy of postsynthetic metathesis
and oxidation (PSMO) of the metal nodes step by step. The frameworks
remained in their single crystal form throughout. Furthermore, the
stability and porosity of the frameworks were significantly improved
after PSMO. By taking advantage of both the kinetically labile metal–ligand
exchange reactions prior to oxidation and the kinetically inert metal–ligand
bonds after oxidation, robust MOFs, which would otherwise be difficult
to synthesize, can be readily prepared.