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

Abstract

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.

Enhanced removal of iodide from water induced by a metal-incorporated porous metal–organic framework

“…Metal-organic frameworks (MOFs), constituted by metal ions or clusters with organic ligands, have been explored their potential applications in many fields [10][11][12][13][14][15][16][17][18].…”

Crystalline central-metal transformation in metal-organic frameworks

“…In contrast to the partial substitution achieved in the study by Dincȃ's group, Zhou et al obtained two complete substitution products, PCN-426-Fe(II) and PCN-426-Cr(II), using PCN-426-Mg as a template [86], which were suspended in DMF and bubbled with an airstream, and oxidized to PCN-426-Fe(III) and PCN-426-Cr(III) within minutes, respectively (Fig. 8).…”

“…Hard Lewis acids (such as Fe III , Cr III , Zr IV , and Ti IV ) are usually considered to be good candidates for constructing robust MOFs with a hard Lewis base carboxylate group [86]. In fact, MOFs have rarely been obtained by direct synthesis methods because of the kinetic inertness of the metal-ligand bonds [87,88].…”

“…Given the difficulty of the de novo synthesis of MOFs with high valence metals, several research teams have tried to use a post-synthetic metathesis strategy to generate this type of MOF [89,90]. In addition to direct metal ion exchange with high-valence metal ions, another synthesis procedure called post-synthetic metathesis and oxidation (PSMO) has been recently developed [86]. In this procedure, the first step is the exchange with low valence metal ions, before oxidizing the metal nodes of the exchange product.…”

Self-catalysed aerobic oxidization of organic linker in porous crystal for on-demand regulation of sorption behaviours

“…11). While some oxidation reactions have been used to modify the organic linkers in PCP crystals, strong and environment-unfriendly oxidants (such as nitric acid and dimethyldioxirane), as well as organic solvents are necessary 17,18,[34][35][36] . Compared with the conventional oxidation methods, the solvent-free aerobic oxidation is obviously much greener yet more difficult.…”