A Coordinative Solubilizer Method to Fabricate Soft Porous Materials from Insoluble Metal–Organic Polyhedra

Abstract

Porous molecular cages have a characteristic processability arising from their solubility, which allows their incorporation into porous materials. Attaining solubility often requires covalently bound functional groups that are unnecessary for porosity and which ultimately occupy free volume in the materials, decreasing their surface areas. Here, a method is described that takes advantage of the coordination bonds in metal–organic polyhedra (MOPs) to render insoluble MOPs soluble by reversibly attaching an alkyl‐functionalized ligand. We then use the newly soluble MOPs as monomers for supramolecular polymerization reactions, obtaining permanently porous, amorphous polymers with the shape of colloids and gels, which display increased gas uptake in comparison with materials made with covalently functionalized MOPs.

Synthesis of Polycarboxylate Rhodium(II) Metal–Organic Polyhedra (MOPs) and their use as Building Blocks for Highly Connected Metal–Organic Frameworks (MOFs)

“…[28] However, unlike most flexible MOFs and coordination polymers, which lose their porosity upon activation-triggered amorphization, amorphous RhCu-rht-MOF and both RhCu-ftw-MOFs exhibit permanent porosity. We attributed this feature to the fact that, similarly to the case of previously reported amorphous soft porous materials, [29] amorphization does not entail collapse of the Rh II -MOPs that remain accessible upon activation. Indeed, gas-sorption measurements revealed that all three MOFs are microporous to N 2 , showing BET areas (A BET ) of 700 m 2 g À1 (RhCu-rht-MOF), 400 m 2 g À1 (RhCu-ftw-MOF-1) and 680 m 2 g À1 (RhCu-ftw-MOF-2) (Figures S33,S35,36).…”

Synthesis of Polycarboxylate Rhodium(II) Metal–Organic Polyhedra (MOPs) and their use as Building Blocks for Highly Connected Metal–Organic Frameworks (MOFs)

“…However, unlike most flexible MOFs and coordination polymers, which lose their porosity upon activation‐triggered amorphization, amorphous RhCu‐ rht ‐MOF and both RhCu‐ ftw ‐MOFs exhibit permanent porosity. We attributed this feature to the fact that, similarly to the case of previously reported amorphous soft porous materials, [29] amorphization does not entail collapse of the Rh II ‐MOPs that remain accessible upon activation. Indeed, gas‐sorption measurements revealed that all three MOFs are microporous to N 2 , showing BET areas (A BET ) of 700 m 2 g −1 (RhCu‐ rht ‐MOF), 400 m 2 g −1 (RhCu‐ ftw ‐MOF‐1) and 680 m 2 g −1 (RhCu‐ ftw ‐MOF‐2) (Figures S33,S35,36).…”

Post‐Synthetic Modification of Metal–Organic Frameworks Toward Applications

“…The monodentate ligand is replaced by a bis‐monodentate ligand during the subsequent supramolecular polymerization to form a permanently porous, amorphous polymer with superior gas uptake property compared to the covalently functionalized polymers. [ 84 ] A green pathway of liquid‐assisted grinding was attempted for the linker exchange with a water‐soluble ligand to form a fluorinated UiO‐66 analogue with higher porosity and pore volume. [ 85 ]…”