4 research outputs found

    Total cobalt determination in human blood and synovial fluid using inductively coupled plasma-mass spectrometry: method validation and evaluation of performance variables affecting metal hip implant patient samples

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    <div><p>Inductively coupled plasma with mass spectrometric detection (ICP-MS) has been used for clinical analysis of cobalt (Co) due to its sensitivity and specificity; however, media-specific validation studies are lacking. This study provides data on performance variables affecting differences between selected analytical platforms (Perkin Elmer and Agilent), tissue sample preparation, storage, and interferences affecting measurements in whole blood, serum, and synovial fluid. The limits of detection (LOD) range from 0.2–0.5 µg/L in serum and synovial fluid, and 0.6–1.7 µg Co/L in whole blood. The Agilent platform with collision reaction cell is more sensitive, while the Perkin Elmer platform with dynamic reaction cell demonstrates more polyatomic interferences near the LOD for serum and whole blood. Split sample analysis showed good accuracy, precision, and reproducibility between serum Co measurements using acid digestion or detergent dilution preparations for persons with metal hip implants or following supplement intake. The results demonstrated reliability of the ICP-MS methodology across the two analytical platforms and between two commercial laboratories for Co concentrations above 5 µg Co/L, but digestion procedures and polyatomic interferences may affect measurements in some media at lower concentrations. These studies validate the described ICP-MS methodology for clinical purposes with precautions at low cobalt concentrations (<5 µg Co/L).</p></div

    Cerium-Hydride Secondary Building Units in a Porous Metal–Organic Framework for Catalytic Hydroboration and Hydrophosphination

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    We report the stepwise, quantitative transformation of Ce<sup>IV</sup><sub>6</sub>(μ<sub>3</sub>-O)<sub>4</sub>(μ<sub>3</sub>-OH)<sub>4</sub>­(OH)<sub>6</sub>(OH<sub>2</sub>)<sub>6</sub> nodes in a new Ce-BTC (BTC = trimesic acid) metal–organic framework (MOF) into the first Ce<sup>III</sup><sub>6</sub>(μ<sub>3</sub>-O)<sub>4</sub>(μ<sub>3</sub>-OLi)<sub>4</sub>(H)<sub>6</sub>(THF)<sub>6</sub>Li<sub>6</sub> metal-hydride nodes that effectively catalyze hydroboration and hydrophosphination reactions. CeH-BTC displays low steric hindrance and electron density compared to homogeneous organolanthanide catalysts, which likely accounts for the unique 1,4-regioselectivity for the hydroboration of pyridine derivatives. MOF nodes can thus be directly transformed into novel single-site solid catalysts without homogeneous counterparts for sustainable chemical synthesis

    Single-Site Cobalt Catalysts at New Zr<sub>12</sub>(μ<sub>3</sub>‑O)<sub>8</sub>(μ<sub>3</sub>‑OH)<sub>8</sub>(μ<sub>2</sub>‑OH)<sub>6</sub> Metal–Organic Framework Nodes for Highly Active Hydrogenation of Nitroarenes, Nitriles, and Isocyanides

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    We report here the synthesis of a robust and porous metal–organic framework (MOF), Zr<sub>12</sub>-TPDC, constructed from triphenyl­dicarboxylic acid (H<sub>2</sub>TPDC) and an unprecedented Zr<sub>12</sub> secondary building unit (SBU): Zr<sub>12</sub>(μ<sub>3</sub>-O)<sub>8</sub>­(μ<sub>3</sub>-OH)<sub>8</sub>­(μ<sub>2</sub>-OH)<sub>6</sub>. The Zr<sub>12</sub>-SBU can be viewed as an inorganic node dimerized from two commonly observed Zr<sub>6</sub> clusters via six μ<sub>2</sub>-OH groups. The metalation of Zr<sub>12</sub>-TPDC SBUs with CoCl<sub>2</sub> followed by treatment with NaBEt<sub>3</sub>H afforded a highly active and reusable solid Zr<sub>12</sub>-TPDC-Co catalyst for the hydrogenation of nitroarenes, nitriles, and isocyanides to corresponding amines with excellent activity and selectivity. This work highlights the opportunity in designing novel MOF-supported single-site solid catalysts by tuning the electronic and steric properties of the SBUs

    Single-Site Cobalt Catalysts at New Zr<sub>8</sub>(μ<sub>2</sub>‑O)<sub>8</sub>(μ<sub>2</sub>‑OH)<sub>4</sub> Metal-Organic Framework Nodes for Highly Active Hydrogenation of Alkenes, Imines, Carbonyls, and Heterocycles

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    We report here the synthesis of robust and porous metal–organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis­(<i>p</i>-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M<sub>8</sub>(μ<sub>2</sub>-O)<sub>8</sub>(μ<sub>2</sub>-OH)<sub>4</sub> and octahedral M<sub>6</sub>(μ<sub>3</sub>-O)<sub>4</sub>(μ<sub>3</sub>-OH)<sub>4</sub>. While the M<sub>6</sub>-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M<sub>8</sub>-SBU is composed of eight M<sup>IV</sup> ions in a cubic fashion linked by eight μ<sub>2</sub>-oxo and four μ<sub>2</sub>-OH groups. The metalation of Zr-MTBC SBUs with CoCl<sub>2</sub>, followed by treatment with NaBEt<sub>3</sub>H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr<sub>8</sub>-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis