Self-assembly of metal–organic polyhedra into supramolecular polymers with intrinsic microporosity

Abstract

Designed porosity in coordination materials often relies on highly ordered crystalline networks, which provide stability upon solvent removal. However, the requirement for crystallinity often impedes control of higher degrees of morphological versatility, or materials processing. Herein, we describe a supramolecular approach to the synthesis of amorphous polymer materials with controlled microporosity. The strategy entails the use of robust metal–organic polyhedra (MOPs) as porous monomers in the supramolecular polymerization reaction. Detailed analysis of the reaction mechanism of the MOPs with imidazole-based linkers revealed the polymerization to consist of three separate stages: nucleation, elongation, and cross-linking. By controlling the self-assembly pathways, we successfully tuned the resulting macroscopic form of the polymers, from spherical colloidal particles to colloidal gels with hierarchical porosity. The resulting materials display distinct microporous properties arising from the internal cavity of the MOPs. This synthetic approach could lead to the fabrication of soft, flexible materials with permanent porosity.

Self‐Assembly of Metal–Organic Frameworks into Monolithic Materials with Highly Controlled Trimodal Pore Structures

“…The Young's modulus of the samples is in the following order: UiO‐66‐NH 2 gel (solvothermally treated at 110 °C from the dried gel, 100 MPa) > Zr‐BDC‐NH 2 gel (Large‐scale, 75 MPa) > UiO‐66‐NH 2 gel (solvothermally treated at 140 °C from the dried gel, 69 MPa) > UiO‐66‐NH 2 gel (solvothermally treated at 110 °C from the wet gel, 29 MPa) (Table S7). The low crystalline Zr‐BDC‐NH 2 gel had high Young's modulus about 75 MPa, and the solvothermally treated UiO‐66‐NH 2 samples also had enough high mechanical stability comparing to the previously reported macro‐/mesoporous MOF‐ or MOP‐based gels . For the similar crystallinity and macroporous structures, the Young's modulus of the UiO‐66‐NH 2 gels decreases as the mesopore volume of the samples increases (Figure I and Table S7).…”

Controlling the Reactivity of the [P8W48O184]40− Inorganic Ring and Its Assembly into POMZite Inorganic Frameworks with Silver Ions

“…Polyoxometalate‐based framework materials, or POMzites, are an emerging class of configurable all‐inorganic porous materials . Porous materials such as zeolites or metal–organic frameworks, MOFs, are ordered networks whose building units are linked with strong interactions via ionic, covalent, and coordination bonds . Silver ions are often used as a flexible linkers in coordination chemistry, for instance, silver‐linked molybdenum oxide POMs are very stable, both in the solid and liquid phases .…”

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

“…As found previously for C 12 RhMOP , the self‐assembly mechanism could be controlled by changing how bix was added . Thus, 12 mol equiv of bix were added in one portion to a 0.93 m m DMF solution of [ HRhMOP (diz) 12 ].…”

“…Herein, we show how unfunctionalized, insoluble MOPs can be incorporated into porous, amorphous polymers (Figure ). We build on our recent study of polymeric MOPs (polyMOPs) with permanent microporosity synthesized through coordination‐driven supramolecular polymerization, in which the soluble MOP [Rh 2 (C 12 ‐bdc) 2 ] 12 ( C 12 RhMOP ; C 12 ‐bdc 2− =5‐dodecoxybenzene‐1,3‐dicarboxylate) was used as an intrinsically porous monomer. There, the dodecoxy chains that made the MOPs soluble occupied free volume in the final assembly, hindering gas diffusion, and lowering the capacity of the polyMOPs.…”