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.

Porous Colloidal Hydrogels Formed by Coordination‐Driven Self‐Assembly of Charged Metal‐Organic Polyhedra

“…Due to the coordination of acetonitrile to the MOPs, an absorption maximum of the band (λ max ), associated with the π*-π* transition of the dirhodium paddlewheel moiety, was observed at 559 nm for the solution of ONaRhMOP (Figure S2b), which can be assigned to the chromophore of rhodium paddlewheel complex with two acetonitrile molecules coordinating on the axial sites (Figure S4). [19][20] Note that this shift was independent from the deprotonation degree. After the addition of 12 eq.…”

Multiscale structural control of linked metal–organic polyhedra gel by aging-induced linkage-reorganization

“…The gels made from HRhMOP are attractive targets because the thermal stability of the MOPs allow their internal cavities to be maintained after desolvation process. 30 In contrast to other MOP gels which incorporate polymers as linkers, the use of the short linker bix affords a well-defined hierarchical structure over multiple length scales: isolated MOP cages are crosslinked by bix at the molecular scale, leading to the formation of mesoscale colloidal particles (around 25 nm), followed by their further fusion and percolation to give a colloidal gel network ( Fig. 1 ).…”

“…1). 30,52 The resulting linked MOP network consists of multiscale porosities as molecular MOP cavities, mesoscale external pores between linked MOPs inside the colloids and macropores of the colloidal network. Such hierarchical structure affords optimal molecular diffusion throughout the material to demonstrate permanent porosity for gas sorption.…”

“…27,28 Recently we reported the fabrication of wet gels with hierarchical porous structures by coordinatively linking cuboctahedral MOPs, [Rh 2 (bdc) 2 ] 12 (HRhMOP; bdc ¼ benzene-1,3-dicarboxylate), with bidentate linkers, bix (1,4bis(imidazol-1-ylmethyl)benzene). 29,30 The high structural stability of HRhMOP with intact cavity results in processable gels that are able to withstand the harsh desolvation process to form the corresponding aerogels with permanent microporosity. Despite these achievements, it is still challenging to further characterize and control the permanent porosity of these linked MOPs inside the resulting dried gel materials.…”

Porous Colloidal Hydrogels Formed by Coordination-Driven Self-Assembly of Charged Metal-Organic Polyhedra

“…Due to the coordination of acetonitrile to the MOPs, an absorption maximum of the band (λmax), associated with the p*-s* transition of the dirhodium paddlewheel moiety, was observed at 559 nm for the solution of ONaRhMOP (Figure S2b), which can be assigned to the chromophore of rhodium paddlewheel complex with two acetonitrile molecules coordinating on the axial sites (Figure S3-4). [19][20] Note that this shift was independent from the deprotonation degree. After the addition of 12 eq.…”