Phase-Pure Zirconium Metal–Organic Polyhedra Enabled by a Ligand Substitution Strategy

Abstract

Zirconium-based metal−organic polyhedra (ZrMOPs) are attractive due to their high stabilities, low-cost building blocks, and solubilities relative to their metal−organic framework analogues (e.g., UiO-66); although these sorts of selfassembled cages often form single thermodynamic products, ZrMOP architectures are typically plagued by the formation of both V 4 L 6 "tetrahedra" and V 2 L 3 "lanterns" (V = vertex, L = ligand) as coproducts of their syntheses. In this work, we demonstrate a ligandexchange strategy to isolate previously inaccessible phase-pure ZrMOPs using two different dicarboxylate donors. We also describe characterization methods that can be used to discriminate between the two architectures to confirm our approach provides synthetic selectivity. The phase-pure materials were found to have drastically different Brunauer−Emmett−Teller (BET) areas, with lanterns exhibiting significantly smaller surface areas (4−20 m 2 /g) than the tetrahedral architectures (393−605 m 2 /g), irrespective of counterions or bridging dicarboxylates. By obviating mixed-phase products of synthesis, our generalizable ligand-exchange pathway to phase-pure ZrMOPs enables systematic fundamental studies and will advance the functional use of these materials.

Uncovering tetrazoles as building blocks for constructing discrete and polymeric assemblies

“…5–10 Since the final architecture is made from the association of multiple building blocks, the properties of these blocks are often translated into the final structure. 11–15 This brings us closer to developing artificial analogues of naturally occurring systems. 16,17…”

Study of self-assembly of mixed-ligand metal–organic cages by high-resolution mass spectrometry

“…Zhou's work 18 further corroborated these findings, demonstrating the profound influence of temperature, solvent composition, counter ions, and coordination angles on the Zr-MOC configuration. Recent strides 19 have introduced the strategy of linker exchange as a pioneering method to attain pure configurations of Zr-MOCs. Consequently, our understanding of the self-assembly principles governing homoleptic cages, synthesized via single linkers, has become more nuanced.…”