scholarly journals Construction of C-C bonds via photoreductive coupling of ketones and aldehydes in the metal-organic-framework MFM-300(Cr)

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tian Luo ◽  
Lili Li ◽  
Yinlin Chen ◽  
Jie An ◽  
Chengcheng Liu ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance Spectroscopy ◽  
Metal Organic Framework ◽  
Photochemical Synthesis ◽  
Resonance Spectroscopy ◽  
Reductive Coupling ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Aldehydes And Ketones ◽  
Metal Organic ◽  
Electron Paramagnetic

AbstractConstruction of C-C bonds via reductive coupling of aldehydes and ketones is hindered by the highly negative reduction potential of these carbonyl substrates, particularly ketones, and this renders the formation of ketyl radicals extremely endergonic. Here, we report the efficient activation of carbonyl compounds by the formation of specific host-guest interactions in a hydroxyl-decorated porous photocatalyst. MFM-300(Cr) exhibits a band gap of 1.75 eV and shows excellent catalytic activity and stability towards the photoreductive coupling of 30 different aldehydes and ketones to the corresponding 1,2-diols at room temperature. Synchrotron X-ray diffraction and electron paramagnetic resonance spectroscopy confirm the generation of ketyl radicals via confinement within MFM-300(Cr). This protocol removes simultaneously the need for a precious metal-based photocatalyst or for amine-based sacrificial agents for the photochemical synthesis.

Persistent P-Stabilized Boryl Radicals with Bulky Substituents at Boron

Synthesis ◽  
2018 ◽  
Vol 50 (18) ◽  
pp. 3671-3678
Author(s):  
Didier Bourissou ◽  
Amos Rosenthal ◽  
Sonia Mallet-Ladeira ◽  
Ghenwa Bouhadir
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Room Temperature ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Radical Reactivity ◽  
Different Types ◽  
Electron Paramagnetic

Two new P-stabilized boryl radicals [Ph2P(naph)BAr] (Ar = Tip and Ter) have been prepared and characterized by electron paramagnetic resonance spectroscopy. These radicals are persistent for several days in solution at room temperature. The high steric congestion at boron does not prevent radical reactivity. Two different types of dimerization equilibrium have been observed. The structures of the dimers have been unambiguously established by X-ray diffraction crystallography.

X-RAY DIFFRACTION AND ELECTRON PARAMAGNETIC RESONANCE STUDIES OF A Bi4Sr2.5Ca2.5Cu4Ox SUPERCONDUCTING PHASE

1989 ◽  
Vol 03 (17) ◽  
pp. 1319-1325
Author(s):  
TH. LEVENTOURI ◽  
N. GUSKOS ◽  
M. CALAMIOTOU ◽  
O. PAPAGEORGIOU ◽  
S. PARASKEVAS ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Local Symmetry ◽  
Solid State Reaction Method ◽  
Superconducting Phase ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Electron Paramagnetic

We report a study of a low T c phase of the bismuth superconductor. A nominally Bi 4 Sr 2.5 Ca 2.5 Cu 4 O x compound was produced by the solid state reaction method with a T c = 80 K . X-ray diffraction studies show that the structure is very similar to the structure of the 4:3:3:4 composition with indications of small amounts of other phases. Electron paramagnetic resonance spectroscopy gives a strong Cu 2+ signal at temperatures above T c . We make a comparison between the local symmetry of the Cu 2+ ion complexes in this Bi sample and in the Y–Ba–Cu–O superconductor we had studied before.

Incorporation of Vanadium and Molybdenum into Yttrium-Arsenotungstates Supported by Amino Acid Ligands

2020 ◽  
Vol 73 (3) ◽  
pp. 137
Author(s):  
Fateme Akhlaghi Bagherjeri ◽  
Chris Ritchie ◽  
Robert W. Gable ◽  
Gary Bryant ◽  
Colette Boskovic
Keyword(s):  
Amino Acid ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Central Core ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Uv Visible ◽  
Visible Reflectance ◽  
Electron Paramagnetic

The preference for incorporation of molybdenum over tungsten into specific sites of a family of yttrium-arsenotungstates with amino acid ligands prompted exploration of the incorporation of other metals, affording three new vanadium-containing (V/W and V/Mo/W) analogues: K2(GlyH)10[As4(V2W2)W44Y4O160(Gly)8(H2O)12]·11Gly (1), (MBAH)9(L-NleH)3[As4(V2W2)W44Y4O160(L-Nle)8(H2O)12] (2), and (MBAH)9(L-NleH)3[As4(V2W2)Mo2W42Y4O160(L-Nle)8(H2O)12] (3) (Gly=glycine and L-Nle=l-norleucine, MBAH=4-methylbenzylammonium). These hybrid polyoxometalates all possess a tetrametallic oxo-bridged {VIV2WVI2} central core surrounded by an amino acid-ligated cyclic metal-oxo framework. X-Ray photoelectron, UV-visible reflectance, and electron paramagnetic resonance spectroscopy, together with metal analysis, confirm the incorporation of vanadium into the polyoxometalates, while single crystal X-ray diffraction analysis supports the location of the vanadium atoms in the central core.

scholarly journals Influence of MoS2 on Activity and Stability of Carbon Nitride in Photocatalytic Hydrogen Production

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 695 ◽  
Author(s):  
Ramesh P. Sivasankaran ◽  
Nils Rockstroh ◽  
Carsten R. Kreyenschulte ◽  
Stephan Bartling ◽  
Henrik Lund ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Composite Photocatalysts ◽  
Electron Transfer Properties ◽  
Electron Paramagnetic

MoS2/C3N4 (MS-CN) composite photocatalysts have been synthesized by three different methods, i.e., in situ-photodeposition, sonochemical, and thermal decomposition. The crystal structure, optical properties, chemical composition, microstructure, and electron transfer properties were investigated by X-ray diffraction, UV-vis diffuse reflectance spectroyscopy, X-ray photoelectron spectroscopy, electron microscopy, photoluminescence, and in situ electron paramagnetic resonance spectroscopy. During photodeposition, the 2H MoS2 phase was formed upon reduction of [MoS4]2− by photogenerated conduction band electrons and then deposited on the surface of CN. A thin crystalline layer of 2H MoS2 formed an intimate interfacial contact with CN that favors charge separation and enhances the photocatalytic activity. The 2H MS-CN phase showed the highest photocatalytic H2 evolution rate (2342 μmol h−1 g−1, 25 mg catalyst/reaction) under UV-vis light irradiation in the presence of lactic acid as sacrificial reagent and Pt as cocatalyst.

scholarly journals Biofiltration field study for cold Fe(II)- and Mn(II)-rich groundwater: accelerated Mn(II) removal kinetics and cold-adapted Mn(II)-oxidizing microbial populations

2017 ◽  
Vol 52 (4) ◽  
pp. 229-242 ◽  
Author(s):  
Sandeepraja Dangeti ◽  
Babak Roshani ◽  
Brian Rindall ◽  
Joyce M. McBeth ◽  
Wonjae Chang
Keyword(s):  
Electron Paramagnetic Resonance Spectroscopy ◽  
Pilot Scale ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Cold Adapted ◽  
Filter Materials ◽  
Biogenic Mn Oxides ◽  
Electron Paramagnetic ◽  
Autocatalytic Oxidation

Abstract Removal of Mn(II) from Fe(II)- and Mn(II)-rich groundwater in cold regions is challenging, due to slow Mn(II) removal kinetics below 15 °C. This study demonstrated onset, acclimation, and acceleration of Mn(II) removal in a two-stage pilot-scale biofilter (Fe and Mn filters) at varying low on-site temperatures (8–14.8 °C). Mn(II) removal commenced at 8 °C in the Mn filter after Fe(II) removal. A shift in redox-pH conditions favored biological Mn(II) removal and Mn(II)-oxidizing bacteria increased. The Mn filter reached steady-state functioning after 97 days, exhibiting high removal efficiencies (97 ± 0.9%). Yet, first-order rate constants (k) for Mn(II) removal were low (10−6–10−5 min−1; t1/2 = ∼40 d). After consecutive backwashes and filter inoculation with backwashed sludge, k remarkably accelerated to 0.21 min−1 (t1/2 = 3.31 min at 11 ± 0.6 °C). The cold-adapted microbial consortium (51 genera), including Pseudomonas, Leptothrix, Flavobacterium, and Zoogloea, cultured from the field-aged biofilter rapidly produced biogenic Mn oxides at 8 °C, confirmed by electron paramagnetic resonance spectroscopy. Birnessite and pyrolusite detected by synchrotron-based powder X-ray diffraction, and a repetitive birnessite-like surface morphology on ripened filter materials, reflected autocatalytic oxidation. Shifting in k indicated the vertical progress of biofilter ripening, which was not limited by low temperature.

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