Metalation of a Thiocatechol-Functionalized Zr(IV)-Based Metal–Organic Framework for Selective C–H Functionalization

The incorporation of 2,3-dimercaptoterephthalate (thiocatecholate, tcat) into a highly robust UiO-type metal–organic framework (MOF) has been achieved via postsynthetic exchange (PSE). The anionic, electron-donating thiocatecholato motif provides an excellent platform to obtain site-isolated and coordinatively unsaturated soft metal sites in a robust MOF architecture. Metalation of the thiocatechol group with palladium affords unprecedented Pd-mono­(thio­catecholato) moieties within these MOFs. Importantly, Pd-metalated MOFs are efficient, heterogeneous, and recyclable catalysts for regioselective functionalization of sp² C–H bond. This material is a rare example of chelation-assisted C–H functionalization performed by a MOF catalyst

Enhanced Electrocatalytic Oxygen Evolution by Exfoliation of a Metal–Organic Framework Containing Cationic One-Dimensional [Co₄(OH)₂]⁶⁺ Chains

Metal–organic frameworks (MOFs) are an emerging class of heterogeneous electrocatalyst, though the focus for the vast majority of them has been on employing them as a precursor for carbon materials or as a host material for encapsulating catalytically active species. Herein, we report the preparation of a metal–organic nanosheet with one-dimensional (1-D) [Co₄(OH)₂]⁶⁺ chains via delamination of a 3-D MOF. The resultant atomically thin nanosheets are highly active, robust, and recyclable oxygen evolution reaction (OER) electrocatalysts with a low overpotential 318 mV (without <i>iR</i> compensation) to achieve a current density of 10 mA cm^–2. These values along with the small Tafel slope (54 mV dec^–1) exhibit a superior performance to the bulk MOF precursor and the benchmark RuO₂ catalyst under the identical condition. The electrochemical studies ascribe the excellent OER activity to the high surface area, accessible Co^II sites, and good charge transfer of the nanosheets

Unusual Missing Linkers in an Organosulfonate-Based Primitive–Cubic (pcu)-Type Metal–Organic Framework for CO₂ Capture and Conversion under Ambient Conditions

A noninterpenetrated organosulfonate-based metal–organic framework (MOF) with a defective primitive–cubic (pcu) topology was successfully synthesized. The unusual missing linkers, along with the highest permanent porosity (∼43%) in sulfonate-MOFs, offer a versatile platform for the incorporation of alkynophilic Ag­(I) sites. The cyclic carboxylation of alkyne molecules (e.g., propargyl alcohol and propargyl amine) into α-alkylidene cyclic carbonates and oxazolidinones were successfully catalyzed by the use of Ag­(I)-embedded sulfonate-MOF under atmospheric pressure of CO₂. In all the three catalytic reactions using CO₂ as a C1 feedstock, the highly robust sulfonate-based MOF catalyst exhibit at least three-cycle reusability

Unusual Missing Linkers in an Organosulfonate-Based Primitive–Cubic (pcu)-Type Metal–Organic Framework for CO₂ Capture and Conversion under Ambient Conditions

A noninterpenetrated organosulfonate-based metal–organic framework (MOF) with a defective primitive–cubic (pcu) topology was successfully synthesized. The unusual missing linkers, along with the highest permanent porosity (∼43%) in sulfonate-MOFs, offer a versatile platform for the incorporation of alkynophilic Ag­(I) sites. The cyclic carboxylation of alkyne molecules (e.g., propargyl alcohol and propargyl amine) into α-alkylidene cyclic carbonates and oxazolidinones were successfully catalyzed by the use of Ag­(I)-embedded sulfonate-MOF under atmospheric pressure of CO₂. In all the three catalytic reactions using CO₂ as a C1 feedstock, the highly robust sulfonate-based MOF catalyst exhibit at least three-cycle reusability

Enhanced Electrocatalytic Oxygen Evolution by Exfoliation of a Metal–Organic Framework Containing Cationic One-Dimensional [Co₄(OH)₂]⁶⁺ Chains

Metal–organic frameworks (MOFs) are an emerging class of heterogeneous electrocatalyst, though the focus for the vast majority of them has been on employing them as a precursor for carbon materials or as a host material for encapsulating catalytically active species. Herein, we report the preparation of a metal–organic nanosheet with one-dimensional (1-D) [Co₄(OH)₂]⁶⁺ chains via delamination of a 3-D MOF. The resultant atomically thin nanosheets are highly active, robust, and recyclable oxygen evolution reaction (OER) electrocatalysts with a low overpotential 318 mV (without <i>iR</i> compensation) to achieve a current density of 10 mA cm^–2. These values along with the small Tafel slope (54 mV dec^–1) exhibit a superior performance to the bulk MOF precursor and the benchmark RuO₂ catalyst under the identical condition. The electrochemical studies ascribe the excellent OER activity to the high surface area, accessible Co^II sites, and good charge transfer of the nanosheets

A Cationic Antimonite Chain Templated by Sulfate: [Sb₆O₇⁴⁺][(SO₄^2–)₂]

An extended metal oxide possessing a cationic charge on the host has been synthesized by hydrothermal methods. The structure consists of 1D antimony oxide [Sb₆O₇]⁴⁺ chains with a new structural motif of four Sb atoms wide and unprotonated sulfate anions between the chains. The material was characterized by powder and single-crystal X-ray diffraction. Thermal behavior and chemical resistance in aqueous acidic conditions (pH ∼2) indicate a highly stable cationic material. The stability is attributed to the entirely inorganic composition of the structure, where 1D covalently extended chains are electrostatically bound to divalent anions

A Cationic Antimonite Chain Templated by Sulfate: [Sb₆O₇⁴⁺][(SO₄^2–)₂]

An extended metal oxide possessing a cationic charge on the host has been synthesized by hydrothermal methods. The structure consists of 1D antimony oxide [Sb₆O₇]⁴⁺ chains with a new structural motif of four Sb atoms wide and unprotonated sulfate anions between the chains. The material was characterized by powder and single-crystal X-ray diffraction. Thermal behavior and chemical resistance in aqueous acidic conditions (pH ∼2) indicate a highly stable cationic material. The stability is attributed to the entirely inorganic composition of the structure, where 1D covalently extended chains are electrostatically bound to divalent anions

Anion Exchange of the Cationic Layered Material [Pb₂F₂]²⁺

We demonstrate the complete exchange of the interlamellar anions of a 2-D cationic inorganic material. The α,ω-alkanedisulfonates were exchanged for α,ω-alkanedicarboxylates, leading to two new cationic materials with the same [Pb₂F₂]²⁺ layered architecture. Both were solved by single crystal X-ray diffraction and the transformation also followed by in situ optical microscopy and ex situ powder X-ray diffraction. This report represents a rare example of metal–organic framework displaying highly efficient and complete replacement of its anionic organic linker while retaining the original extended inorganic layer. It also opens up further possibilities for introducing other anions or abatement of problematic anions such as pharmaceuticals and their metabolites

Enhanced Photochemical Hydrogen Production by a Molecular Diiron Catalyst Incorporated into a Metal–Organic Framework

A molecular proton reduction catalyst [FeFe]­(dcbdt)­(CO)₆ (<b>1</b>, dcbdt = 1,4-dicarboxylbenzene-2,3-dithiolate) with structural similarities to [FeFe]-hydrogenase active sites has been incorporated into a highly robust Zr­(IV)-based metal–organic framework (MOF) by postsynthetic exchange (PSE). The PSE protocol is crucial as direct solvothermal synthesis fails to produce the functionalized MOF. The molecular integrity of the organometallic site within the MOF is demonstrated by a variety of techniques, including X-ray absorption spectroscopy. In conjunction with [Ru­(bpy)₃]²⁺ as a photosensitizer and ascorbate as an electron donor, MOF-[FeFe]­(dcbdt)­(CO)₆ catalyzes photochemical hydrogen evolution in water at pH 5. The immobilized catalyst shows substantially improved initial rates and overall hydrogen production when compared to a reference system of complex <b>1</b> in solution. Improved catalytic performance is ascribed to structural stabilization of the complex when incorporated in the MOF as well as the protection of reduced catalysts <b>1</b>^– and <b>1</b>^2– from undesirable charge recombination with oxidized ascorbate

A Cationic Metal–Organic Solid Solution Based on Co(II) and Zn(II) for Chromate Trapping

We report the synthesis and characterization of a solid solution series of cationic metal–organic materials with full compositional range from pure Co­(II) to Zn­(II) end-members. The materials consist of [Zn_<i>x</i>­Co_1–<i>x</i>­(H₂O)₄­(4,4′-bipy)₂]²⁺ metal–organic clusters that π–π stack into 2-D positively charged layers, with the metal ratio tunable by molar ratio under hydrothermal conditions. The interlamellar α,ω-alkane­disulfonate serves as an anionic template and noncovalently interacts with the cationic layers. The weak interaction allows anion exchange for toxic oxometal anions, such as chromate, CrO₄^2–. The highest chromate adsorption capacity was 68.5 mg/g (0.43 mol/mol) for the as-synthesized 50 mol % Co­(II)-incorporated material. Our cationic material can also selectively trap these toxic oxo-anions when nontoxic anions (e.g., nitrate, sulfate) were present in an over 50-fold excess concentration