Reversible Discrete-to-Extended Metal–Organic Polyhedra Transformation by Sulfonic Acid Surface Functionalization

Abstract

Metal−organic polyhedra (MOPs) are molecular porous units in which desired functionalities can be installed with precise geometrical and compositional control. By combing two complementary chemical moieties, such as sulfonic acid groups and Rh(II)−carboxylate paddlewheel, we synthesized a robust water-soluble cuboctahedral MOP with excellent features in both solution and solid states. Herein, we demonstrate that the superior chemical stability of the Rh 2 unit and the elevated number of functional groups on the surface (24 per cage) result in a porous cage with high solubility and stability in water, including acidic, neutral, and basic pH conditions. We also prove that the sulfonic acid-rich form of the cage can be isolated through postsynthetic acid treatment. This transformation involves an improved gas uptake capacity and the capability to reversibly assemble the cages into a threedimensional (3D) metal−organic framework (MOF) structure. Likewise, this sulfonic acid functionalization provides both MOP and MOF solids with high proton conductivities (>10 −3 S cm −1 ), comparable to previously reported high conducting metal−organic materials. The influence of the MOP-to-MOF processing in the gas adsorption capacity indicates that this structural transformation can provide materials with higher and more controllable porous properties. These results illustrate the high potential of acidic MOPs as more flexible porous building units in terms of processability, structural complexity, and tunability of the properties.

Porous supramolecular gels produced by reversible self-gelation of ruthenium-based metal–organic polyhedra

“…4b), which corresponds to the size of the MOP cavity, as it has been evidenced by previous studies of analogous cuboctahedral MOPs. 25,44,50…”

“…4b), which corresponds to the size of the MOP cavity, as it has been evidenced by previous studies of analogous cuboctahedral MOPs. 25,44,50 Besides, OH-RuMOP-agel showed a type-II isotherm with high sorption at the low relative pressure (z170 cm 3 g −1 at P/P 0 = 0.1), and a S BET (BETSI) value of 717 m 2 g −1 (Fig. S30 †), which represents a moderate increment compared to OH-RuMOP [BF 4 ] 12 .…”

Controlled Self-Assembly, Isomerism, and Guest Uptake/Release of Charge-Reversible Lanthanide–Organic Octahedral Cages

“…However, preparing coordination assemblies capable of charge regulation, particularly charge reversibility, remains a challenging task. This is because changes in the charging state of ligands or metal centers greatly affect the structural integrity of metallosupramolecular assemblies, often causing their dissociation or rearrangement. , Successful cases are still rare and usually involve an ingenious design, including utilizing metal ions with variable valences − or decorating electron- − or proton- ,− buffering groups on the organic ligands, which enables orthogonal regulation of the charges of assemblies. Recently, Su et al.…”

High Temperature Self‐Regenerative Granular Hydrogels for Fracture Treatments During Subsurface Energy Recovery

“…Injectable hydrogels with re-shaping flexibility and mechanical integrity are attractive for their applications in tissue repair and soft robotics. [1][2][3][4][5][6][7][8][9] In particular, injectable granular hydrogels can be assembled to re-form bulk hydrogels in irregular tissue defects through chemical or physical interactions along the interfaces. To impart self-crosslinking function for regenerating robust structural tissue complexes, granular hydrogels should have strong interactions upon fully hydration without external interventions while maintaining shear-thinning property for injectivity.…”