An Exceptionally Stable Metal–Organic Framework Constructed from Chelate-Based Metal–Organic Polyhedra

Abstract

We report the rational design and synthesis of a water-stable metal–organic framework (MOF), Fe-HAF-1, constructed from supramolecular, Fe3+-hydroxamate-based polyhedra with mononuclear metal nodes. Owing to its chelate-based construction, Fe-HAF-1 displays exceptional chemical stability in organic and aqueous solvents over a wide pH range (pH 1–14), including in the presence of 5 M NaOH. Despite the charge neutrality of the Fe3+-tris­(hydroxamate) centers, Fe-HAF-1 crystals are negatively charged above pH 4. This unexpected property is attributed to the formation of defects during crystallization that results in uncoordinated hydroxamate ligands or hydroxide-coordinated Fe centers. The anionic nature of Fe-HAF-1 crystals enables selective adsorption of positively charged ions in aqueous solution, resulting in efficient separation of organic dyes and other charged species in a size-selective fashion. Fe-HAF-1 presents a new addition to a small group of chelate-based MOFs and provides a rare framework whose 3D connectivity is exclusively formed by metal–hydroxamate coordination.

Fe(III)‐Functionalized Magnetic Covalent Organic Frameworks for Fast Adsorption and Removal of Phenylbutazone in Aqueous Solution

“…When the pH decreased from 4.5 to 1.5, the negatively charged phenylbutazone ions are reduced, and the electrostatic interaction between MCOF(Fe) and phenylbutazone is weakened. However, when pH>5.3, the formation of Fe(III) ions with hydroxide ligands in MCOF(Fe) would promote its electronegativity . The electrostatic repulsion occured between MCOF(Fe) and phenylbutazone anions, leading to the attenuation of adsorption capacity.…”

“…However, when pH > 5.3, the formation of Fe(III) ions with hydroxide ligands in MCOF(Fe) would promote its electronegativity. [63] The electrostatic repulsion occured between MCOF(Fe) and phenylbutazone anions, leading to the attenuation of adsorption capacity. Therefore, it was concluded that the applied pH was adjusted to 5.0 � 0.2 to obtain the best adsorption capacity.…”

MOF‐Based Hybrids for Solar Fuel Production

“…Chiong et al. [ 111 ] reported that Fe‐HAF‐1 is stable in ammonium hydroxide, trimethylamine, pyridine, methanol, acetic acid, acetonitrile, and acetone for 1 week. Hu et al.…”

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

“…In metal‐organic frameworks (MOFs), MOPs are used for the rational construction of highly‐connected nets following the well‐known supermolecular building block (SBB) approach [6, 7] . In this approach, the in situ assembly of the MOP is traditionally harnessed to guide formation of a targeted MOF with a given topology [8–13] …”