Invisible Silver Guests Boost Order in a Framework That Cyclizes and Deposits Ag₃Sb Nanodots

Abstract

The infusion of metal guests into (i.e., metalating) the porous medium of metal−organic frameworks (MOFs) is a topical approach to wide-ranging functionalization purposes. We report the notable interactions of AgSbF 6 guests with the designer MOF host ZrL1 [Zr 6 O 4 (OH) 7 (L1) 4.5 (H 2 O) 4 ]. (1) The heavyatom guests of AgSbF 6 induce order in the MOF host to allow the movable alkyne side arm to be fully located by X-ray diffraction, but they themselves curiously remain highly disordered and absent in the strucutral model. The enhanced order of the framework can be generally ascribed to interaction of the silver guests with the host alkyne and thioether functions, while the invisible heavy-atom guest represents a new phenomenon in the metalation of open framework materials. (2) The AgSbF 6 guests also participate in the thermocyclization of the vicinal alkyne units of the L1 linker (at 450 °C) and form the rare nanoparticle of Ag 3 Sb supported on the concomitantly formed nanographene network. The resulted composite exhibits high electrical conductivity (1.0 S/cm) as well as useful, mitigated catalytic activity for selectively converting nitroarenes into the industrially important azo compounds, i.e., without overshooting to form the amine side products. The heterogeneous/cyclable catalysis entails only the cheap reducing reagents of NaBH 4 , ethanol, and water, with yields being generally close to 90%.Article pubs.acs.org/IC

A Ferrocene Metal–Organic Framework Solid for Fe-Loaded Carbon Matrices and Nanotubes: High-Yield Synthesis and Oxygen Reduction Electrocatalysis

“…Powder X-ray diffraction (PXRD; Figure ) of the as-made sample reveals a crystalline lattice similar to that of PCN-111 ( Fm 3̅ m ; No. 225; a = 33.66 Å) and a recent Zr-MOF based on an analog of H 2 L1 , both of which resemble the UiO series featuring an fcc (face-centered cubic) array of Zr 6 O 4 (OH) 4 clusters connected by L1 molecules. Pawley refinement (Figure S1) discloses a slightly larger cubic cell than PCN-111, with a = 34.11 Å.…”

“…That is why an alkyne-based, carbon-rich linker molecule like H 2 L1 and its MOF derivatives are useful. As recently demonstrated, the dense array of alkyne units can be cyclized into nanographene units starting at about 200 °C, which helps fixate the carbon components for high-yield carbonization. − The structurally well-defined linker and MOF solid as the main carbon feed also ensure consistent sample conditions for carbonization, so as to promote product uniformity. A robust MOF matrix (e.g., one based on Zr 4+ ions), based on the alkyne-equipped linker as such, generally remains porous throughout the carbonization process − and therefore allows for the penetration of small (e.g., N-containing) guests for (nitrogen) doping, which is important for electrochemical catalytic properties .…”

A Ferrocene MetalOrganic Framework Solid for Fe-Loaded Carbon Matrices and Nanotubes: High-Yield Synthesis and Oxygen Reduction Electrocatalysis

“…The residue was purified by column chromatography (silica gel, 1:1 hexane / dichloromethane as eluent) to provide M2 as a white powder (378.4 mg, 76% based on M1). 1 Synthesis of Me2L1. A mixture of M2 (200 mg, 0.42 mmol), ethynylferrocene (234.4 mg, 1.26 mmol), bis(triphenylphosphine)palladium(II) chloride (14.7 mg, 0.02 mmol), triphenylphosphine (11.0 mg, 0.04 mmol) and copper(I) iodide (8.0 mg, 0.04 mmol) were added to a 25 mL Schlenk tube and the tube was connected to a nitrogen manifold.…”

“…After cooling to room temperature, the solvents were removed by filtration and the residue was washed with dichloromethane until filtrate becomes light orange then naturally dried to afford an orange solid (200 mg, 65% yield based on M2). 1 Synthesis of H2L1. Me2L1 (200 mg, 0.27 mmol) was added to a two-neck roundbottom flask charged with a magnetic stirring bar and connected to a nitrogen manifold.…”

“…A red precipitate formed, was collected by filtration, and washed extensively with distilled water, yielding H2L1 as a red solid (171.2 mg, 89% based on Me2L1). 1 After heating to 1000 °C, the residual weight is 77.8%. Assuming no escape of Fe or Zr atoms, the Fe content in the residue can be calculated to be 11.81%/77.8% = 15.2%; Zr, 12.86%/77.8% = 16.5%; assuming O existing only in ZrO2 (e.g., no iron oxides, as iron is as Fe/Fe3C), the O content is calculated to be 16.5% x (2O/Zr) = 16.5 x 32/91 % = 5.8%.…”