scholarly journals Synergy of diffraction and spectroscopic techniques to unveil the crystal structure of antimonic acid

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. F. Mayer ◽  
J. E. Rodrigues ◽  
I. Sobrados ◽  
J. Gainza ◽  
M. T. Fernández-Díaz ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffusion Mechanism ◽  
Pyrochlore Structure ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Spectroscopic Techniques ◽  
X Ray ◽  
Proton Diffusion ◽  
Antimonic Acid

AbstractThe elusive crystal structure of the so-called ‘antimonic acid’ has been investigated by means of robust and state-of-the-art techniques. The synergic results of solid-state magic-angle spinning nuclear magnetic resonance spectroscopy and a combined Rietveld refinement from synchrotron X-ray and neutron powder diffraction data reveal that this compound contains two types of protons, in a pyrochlore-type structure of stoichiometric formula (H3O)1.20(7)H0.77(9)Sb2O6. Some protons belong to heavily delocalized H3O+ subunits, while some H+ are directly bonded to the oxygen atoms of the covalent framework of the pyrochlore structure, with O–H distances close to 1 Å. A proton diffusion mechanism is proposed relying on percolation pathways determined by bond-valence energy landscape analysis. X-ray absorption spectroscopy results corroborate the structural data around Sb5+ ions at short-range order. Thermogravimetric analysis and differential scanning calorimetry endorsed the conclusions on the water content within antimonic acid. Additional 0.7 water molecules per formula were assessed as moisture water by thermal analysis.

scholarly journals Unveiling the crystal structure of ‘antimonic acid’: short- and long-range perspectives

2021 ◽  
Author(s):  
S. F. Mayer ◽  
J. E. Rodrigues ◽  
I. Sobrados ◽  
J. Gainza ◽  
M. T. Fernández-Díaz ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffusion Mechanism ◽  
Pyrochlore Structure ◽  
Structural Data ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Proton Diffusion ◽  
Neutron Powder Diffraction Data ◽  
Antimonic Acid ◽  
Shortrange Order

Abstract The elusive crystal structure of the socalled “antimonic acid” has been investigated by means of robust and state-of-the-art techniques. The synergic results of solidstate magicangle spinning nuclear magnetic resonance spectroscopy and a combined Rietveld refinement from synchrotron X-ray and neutron powder diffraction data reveal that this compound contains two types of protons, in a pyrochloretype structure of stoichiometric formula (H3O)1.20(7)H0.77(9)Sb2O6. Some protons belong to heavily delocalized H3O+ subunits, while some H+ are directly bonded to the oxygen atoms of the covalent framework of the pyrochlore structure, with O − H distances close to 1 Å. A proton diffusion mechanism is proposed relying on percolation pathways determined by bondvalence energy landscape analysis. Xray absorption spectroscopy results corroborate the structural data around Sb5+ ions at shortrange order. Thermogravimetric analysis and differential scanning calorimetry endorsed the conclusions on the water content within antimonic acid. Additional 0.7 water molecules per formula were assessed as moisture water by thermal analysis.

Structural Properties of a Dimeric Phenylcyanamidocopper(I) Complex, [{Cu(PPh3)2(C6H5NCN)}2]

2000 ◽  
Vol 53 (12) ◽  
pp. 971 ◽  
Author(s):  
Eric W. Ainscough ◽  
Andrew M. Brodie ◽  
Peter C. Healy ◽  
Joyce M. Waters
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Structural Properties ◽  
Structure Determination ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Cross Polarization ◽  
X Ray ◽  
Angle Spinning

The X-ray crystal structure determination of bis[-(phenylcyanamido)bis(triphenylphosphine)copper(I)], [{Cu(PPh3)2(C6H5NCN)}2], (1) is reported. The complex has a centrosymmetric dimeric structure with the phenylcyanamide ligands bridging the copper atoms in a -1,3-fashion. The structure is compared with that of the 4-methylphenylcyanamido complex, [{Cu(PPh3)2(4-MeC6H4NCN)}2] (2), and the differences observed in the Cu–P bond lengths compared with changes in the solid state 31P cross-polarization magic-angle spinning (CPMAS) spectra of the two complexes.

scholarly journals Use of Ecuadorian natural and acid-surfactant modified zeolites for remediation of oil- contaminated soils

2019 ◽  
Vol 9 (1) ◽  
pp. 93-104 ◽  
Author(s):  
Gladys Cristina Pinto-Santamaría ◽  
Carlos Alberto Ríos- Reyes ◽  
Luz Yolanda Vargas- Fiallo
Keyword(s):  
Contaminated Soil ◽  
Contaminated Soils ◽  
Oil Spills ◽  
Magic Angle Spinning ◽  
Absorption Capacity ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Experimental Conditions ◽  
X Ray ◽  
Modified Zeolites

Oil spills have been one of the greatest environmental problems worldwide. The contamination of soils due to oil spills generates an oil migration down the soil until reaching groundwater. The research focused on remediation of oil-contaminated soils by Ecuadorian natural and acid-surfactant modified zeolites of the Cayo Formation. The natural and modified zeolites were characterized by wavelength dispersive X-ray fluorescence, X-ray powder diffraction, environmental scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and solid-state magic-angle spinning nuclear magnetic resonance spectroscopy. The natural and modified zeolites were added to an artificially oil-contaminated soil to immobilize and limit the uptake of contaminants by rape through changing soil physical and chemical properties in the pot experiment under greenhouse conditions. Several oil contaminated soil-zeolite mixes were tested in replicated laboratory analyses in terms of their ability to absorb oil. Results indicated that the addition of natural and modified zeolites could increase or decrease soil pH and absorption capacity, with high potential in removing oil from soil. Statistical analysis of the experimental data was performed by the variance test analysis. The absorption process had an efficiency of 46% under well-optimized experimental conditions, with an absorbent dose of 30-M, pH = 3.8 and 15 days of contact time.

scholarly journals Single-crystal X-ray diffraction and NMR crystallography of a 1:1 cocrystal of dithianon and pyrimethanil

2017 ◽  
Vol 73 (3) ◽  
pp. 149-156 ◽  
Author(s):  
Ann-Christin Pöppler ◽  
Emily K. Corlett ◽  
Harriet Pearce ◽  
Mark P. Seymour ◽  
Matthew Reid ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Chemical Shifts ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Double Quantum ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Crystallography

A single-crystal X-ray diffraction structure of a 1:1 cocrystal of two fungicides, namely dithianon (DI) and pyrimethanil (PM), is reported [systematic name: 5,10-dioxo-5H,10H-naphtho[2,3-b][1,4]dithiine-2,3-dicarbonitrile–4,6-dimethyl-N-phenylpyrimidin-2-amine (1/1), C14H4N2O2S2·C12H13N2]. Following an NMR crystallography approach, experimental solid-state magic angle spinning (MAS) NMR spectra are presented together with GIPAW (gauge-including projector augmented wave) calculations of NMR chemical shieldings. Specifically, experimental 1H and 13C chemical shifts are determined from two-dimensional 1H–13C MAS NMR correlation spectra recorded with short and longer contact times so as to probe one-bond C—H connectivities and longer-range C...H proximities, whereas H...H proximities are identified in a 1H double-quantum (DQ) MAS NMR spectrum. The performing of separate GIPAW calculations for the full periodic crystal structure and for isolated molecules allows the determination of the change in chemical shift upon going from an isolated molecule to the full crystal structure. For the 1H NMR chemical shifts, changes of 3.6 and 2.0 ppm correspond to intermolecular N—H...O and C—H...O hydrogen bonding, while changes of −2.7 and −1.5 ppm are due to ring current effects associated with C—H...π interactions. Even though there is a close intermolecular S...O distance of 3.10 Å, it is of note that the molecule-to-crystal chemical shifts for the involved sulfur or oxygen nuclei are small.

Sol-gel synthesis of a nanoparticulate aluminosilicate precursor for homogeneous mullite ceramics

2006 ◽  
Vol 21 (5) ◽  
pp. 1279-1285 ◽  
Author(s):  
Jarkko Leivo ◽  
Mika Lindén ◽  
Cilâine V. Teixeira ◽  
Janne Puputti ◽  
Jessica Rosenholm ◽  
...  
Keyword(s):  
Spinel Phase ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Density ◽  
Angle Spinning ◽  
Sol Gel Synthesis

An amorphous nanoparticulate aluminosilicate 3/2-mullite precursor has been synthesized and carefully characterized. The sol contained 2-nm particles of Q3(3Al) silica species together with six-coordinated alumina, which suggested an allophane-like structure of the nanoparticles. The sol remained stable for years, and formed an easily redispersible physical gel upon solvent evaporation. The gel crystallized to mullite at temperatures below 1000 °C, without going through any intermediate spinel phase. Thus, the nanoparticulate precursor is regarded as a homogeneous high-purity mullite precursor with a high Si–O–Al bond density, which is useful in the preparation of various nanostructured Al-rich aluminosilicate materials. The sols and gels were characterized by small-angle x-ray scattering, dynamic light scattering, x-ray diffraction, 27Al and 29Si magic-angle spinning (MAS) nuclear magnetic resonance spectroscopy, and differential thermal analysis.

scholarly journals Structure of a Luminescent MOF-2 Derivative with a Core of Zn(II)-Terephthalate-Isoquinoline and Its Application in Sensing of Xylenes

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 344 ◽  
Author(s):  
Luis D. Rosales-Vázquez ◽  
Iván J. Bazany Rodríguez ◽  
Simón Hernández-Ortega ◽  
Víctor Sánchez-Mendieta ◽  
Alfredo R. Vilchis-Nestor ◽  
...  
Keyword(s):  
Crystal Structure ◽  
13C Nmr ◽  
Metal Organic Framework ◽  
Fluorescence Emission ◽  
Magic Angle Spinning ◽  
High Yield ◽  
Magic Angle ◽  
X Ray ◽  
Metal Organic ◽  
Angle Spinning

A new blue photoluminescent 2D metal–organic framework, 1, with formula {[Zn2(μ2-BDC)2(iQ)2]}∞ has been synthesized in a high yield under solvothermal conditions by reacting Zn(II) ions with 1,4-benzenedicarboxylic acid (H2BDC) and isoquinoline (iQ) in DMF. Compound 1 was thoroughly characterized by single-crystal X-ray diffraction, solid-state cross-polarization magic-angle spinning 13C NMR, X-ray powder diffraction, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), and thermoanalysis. The crystal structure of 1 showed interpenetrated 2D frameworks consisting of dinuclear paddle-wheel cores Zn2; moreover, this material possessed thermostability up to 310 °C. The CPMAS 13C-NMR spectrum of 1 is consistent with the symmetry of the crystal structure. Luminescence studies showed that 1 strongly enhances its fluorescence emission in the presence of xylene isomers with a pronounced selectivity to p-xylene.

Analytical chemical applications of high-resolution nuclear magnetic resonance spectroscopy of solids

1982 ◽  
Vol 305 (1491) ◽  
pp. 591-607 ◽  
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Structural Data ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
General Applicability ◽  
Phenolic Resins ◽  
X Ray ◽  
Angle Spinning

The basis of the combined cross-polarization-magic-angle spinning (c.p.-m.a.s.) experiment, which yields high-resolution n.m.r. spectra of solid materials, is described and the general applicability of the technique, including its quantitative reliability, discussed. Solid-state n.m.r. is in many ways complementary to X-ray diffraction, as shown by its application to amorphous systems in which diffraction methods cannot be used (for example resins, coals, glasses and surface-immobilized catalysts) and also by its application to crystalline materials where X-ray structural data are available but where, for various reasons, a fuller description of the structure may be obtained by n.m.r. Examples include zeolites and chemically exchanging solid systems. The technique also provides a bridge between the solid-state structures of conformationally mobile and charged species as determined by diffraction techniques and the structures of these species in solution. Quantitative reliability of the c.p.-m.a.s. technique has been evaluated for phenolic resins and coals.

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