Application of the relaxation reagent Gd(FOD)3 (1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionate)gadolinium(III) in 1H NMR spectroscopy of adamantoid compounds

1979 ◽  
Vol 44 (2) ◽  
pp. 533-541
Author(s):  
Jiří Karhan ◽  
Milan Hájek ◽  
Zbyněk Ksandr ◽  
Luděk Vodička
Keyword(s):  
Nmr Spectroscopy ◽  
Structure Analysis ◽  
1H Nmr Spectroscopy ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Shift Reagent ◽  
Spin Lattice Relaxation ◽  
Reagent Concentration ◽  
Relaxation Rates ◽  
Spin Lattice

This spin-lattice relaxation times T1 of protons in the presence of the shift reagent Eu(FOD)3-D27 and the relaxation reagent Gd(FOD)3 were employed for the structure analysis of 1-adamantanol, 4-diamantanol, adamantanone, and 2,2-dioxy-2-thiaadamantane. The structure models of the complex adducts of the substrates with Gd(FOD)3 are discussed. The dependence of the corrected spin-lattice relaxation rates on the relaxation reagent concentration is linear only in the region of low concentration.

scholarly journals Methyl Group Rotation and Tunnellingin Crystals of 5-Membered Ring Molecules

1988 ◽  
Vol 43 (1) ◽  
pp. 35-42 ◽  
Author(s):  
A.-S. Montjoie ◽  
W. Müller-Warmuth ◽  
Hildegard Stiller ◽  
J. Stanislawski
Keyword(s):  
Elevated Temperatures ◽  
Inelastic Neutron Scattering ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Inelastic Neutron ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Quantum Tunnelling ◽  
Spin Lattice

Abstract1H NMR spin-lattice relaxation times T1 and -if accessible -level-crossing peaks and inelastic neutron scattering spectra have been measured for solid 2-and 3-methylfuran, 2-and 3-methylthiophene, 3-and 4-methylpyrazole, 1-methylimidazole, and 5-methylisoxazole. From the tunnel splittings, the torsional excitations and the NMR relaxation rates, the molecular dynamics of the methyl rotators has been evaluated between the limits of quantum tunnelling at low temperatures and thermally activated random reorientation at elevated temperatures.

Ionic mobility in Nasicon-type LiMIV2(PO4)3 materials followed by 7Li NMR spectroscopy.

2011 ◽  
Vol 1313 ◽  
Author(s):  
K. Arbi ◽  
I. Sobrados ◽  
M. Hoelzel ◽  
A. Kuhn ◽  
F. Garcia-Alvarado ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Impedance Spectroscopy ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Ionic Mobility ◽  
Spin Lattice Relaxation ◽  
Pulse Field ◽  
Relaxation Rates ◽  
Arrhenius Behavior ◽  
Spin Lattice

AbstractLithium mobility in LiM2(PO4)3 compounds, with M= Ge, Ti, Sn, Zr and Hf, has been investigated by 7Li Nuclear Magnetic Resonance (NMR) spectroscopy in the temperature range 100-500 K. From the analysis of 7Li NMR quadrupole interactions (CQ and η parameters), Li sites occupancy and exchange processes between structural sites have been studied. Below 250K, Li ions are preferentially located at M1 sites in rhombohedral phases, but occupy M12 sites in triclinic ones. At increasing temperatures, Li mobility has been deduced from spin-spin () and spin-lattice relaxation () rates. In this analysis, the presence of two relaxation mechanisms in plots has been associated with departures of conductivity from the Arrhenius behavior. At high temperatures, residence times at M12−T11−T11−T1 and M12 sites become similar and conductivity significantly increase. This superionic state can be achieved by enlarged order-disorder transformations in rhombohedral phases, or by sharp first order transitions in triclinic ones. Results described in the LiTi2(PO4)3 sample have been compared with those obtained in rhombohedral Li1+xTi2-xAlx(PO4)3 and LiTi2-xZrx(PO4)3 series showing respectively higher and lower conductivities. In the case of Li1.2Ti1.8Al0.2(PO4)3, displaying the highest reported conductivity, NMR results are discussed in relation with those obtained by Neutron Diffraction (ND) and Impedance Spectroscopy (IS). Diffusion coefficients determined by NMR Pulse Field Gradient (PFG) technique are similar to those deduced from Impedance Spectroscopy and NMR relaxation data.

Boron-11, boron-10, and nitrogen-14 NMR relaxation rates and quadrupole coupling constants in BH3NH3

1992 ◽  
Vol 70 (9) ◽  
pp. 2420-2423 ◽  
Author(s):  
Glenn H. Penner ◽  
Stephen I. Daleman ◽  
Angela R. Custodio
Keyword(s):  
Relaxation Times ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Coupling Constants ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Orbital Theory ◽  
Spin Lattice ◽  
Quadrupolar Coupling ◽  
Field Gradients

The 11B, 10B, and 14N spin–lattice relaxation times (T1) for aqueous solutions of BH3NH3 were measured by NMR spectroscopy. The results of this investigation are consistent with the nuclear quadrupolar coupling constants reported in previous nuclear quadrupolar resonance and microwave studies. The activation energy associated with rotational reorientation of BH3NH3 in aqueous solution is 11.7 ± 0.6 kJ/mol. Electric field gradients were calculated at various levels of abinitio molecular orbital theory, in order to obtain theoretical 14N and 11B quadrupolar coupling constants. At the highest level of calculation (CI(SD)/6-31G**//MP2/6-31G**), these are in agreement with recently reported microwave results but not with previously reported NQR experiments.

scholarly journals Uncovering Halide Mixing and Octahedral Dynamics in Vacancy-Ordered Double Perovskites by Multinuclear Magnetic Resonance Spectroscopy

2021 ◽  
Author(s):  
Abhoy Karmakar ◽  
Srija Mukhopadhyay ◽  
Pierre Gachod ◽  
Arturo Gomez ◽  
Guy Bernard ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Density Functional ◽  
Variable Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Double Perovskites ◽  
Axially Symmetric ◽  
Spin Lattice

Vacancy-ordered double perovskites Cs<sub>2</sub>SnX<sub>6</sub> (X = Cl, Br, I) have emerged as promising lead-free and ambient-stable materials for photovoltaic and optoelectronic applications. To advance these promising materials, it is crucial to determine the correlations between physical properties and their local structure and dynamics. Solid-state NMR spectroscopy of multiple NMR-active nuclei (<sup>133</sup>Cs, <sup>119</sup>Sn and <sup>35</sup>Cl) in these cesium tin(IV) halides has been used to decode the structure, which plays a key role in the materials’ optical properties. The <sup>119</sup>Sn NMR chemical shifts span approximately 4000 ppm and the <sup>119</sup>Sn spin-lattice relaxation times span three orders of magnitude when the halogen goes from chlorine to iodine in these diamagnetic compounds. Moreover, ultrawideline <sup>35</sup>Cl NMR spectroscopy for Cs<sub>2</sub>SnCl<sub>6</sub> indicates an axially symmetric chlorine electric field gradient tensor with a large quadrupolar coupling constant of <i>ca.</i> 32 MHz, suggesting a chlorine that is directly attached to Sn(IV) ions. Variable temperature <sup>119</sup>Sn spin lattice relaxation time measurements uncover the presence of hidden dynamics of octahedral SnI<sub>6</sub> units in Cs<sub>2</sub>SnI<sub>6</sub> with a low activation energy barrier of 12.45 kJ/mol (0.129 eV). We further show that complete mixed-halide solid solutions of Cs<sub>2</sub>SnCl<sub>x</sub>Br<sub>6−x</sub> and Cs<sub>2</sub>SnBr<sub>x</sub>I<sub>6−x</sub> (0 ≤ x ≤ 6) form at any halogen compositional ratio. <sup>119</sup>Sn and <sup>133</sup>Cs NMR spectroscopy resolve the unique local SnCl<i><sub>n</sub></i>Br<sub>6−<i>n</i></sub>and SnBr<i><sub>n</sub></i>I<sub>6−<i>n</i></sub> (<i>n</i> = 0−6) octahedral and CsBr<i><sub>m</sub></i>I<sub>12−<i>m</i></sub> (<i>m</i> = 0−12) cuboctahedral environments in the mixed-halide samples. The experimentally observed <sup>119</sup>Sn NMR results are consistent with magnetic shielding parameters obtained by density functional theory computations to verify random halogen distribution in mixed-halide analogues. Finally, we demonstrate the difference in the local structures and optical absorption properties of Cs<sub>2</sub>SnI<sub>6</sub> samples prepared by solvent-assisted and solvent-free synthesis routes.

Nuclear spin-lattice relaxation times from continuous wave nmr spectroscopy

1979 ◽  
Vol 56 (5) ◽  
pp. 304 ◽  
Author(s):  
Jan B. Wooten ◽  
John Jacobus ◽  
J. E. Gurst ◽  
William Egan ◽  
W. G. Rhodes ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Nuclear Spin ◽  
Continuous Wave ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nuclear Spin Lattice Relaxation

scholarly journals Uncovering Halide Mixing and Octahedral Dynamics in Vacancy-Ordered Double Perovskites by Multinuclear Magnetic Resonance Spectroscopy

2021 ◽  
Author(s):  
Abhoy Karmakar ◽  
Srija Mukhopadhyay ◽  
Pierre Gachod ◽  
Arturo Gomez ◽  
Guy Bernard ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Density Functional ◽  
Variable Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Double Perovskites ◽  
Axially Symmetric ◽  
Spin Lattice

Vacancy-ordered double perovskites Cs<sub>2</sub>SnX<sub>6</sub> (X = Cl, Br, I) have emerged as promising lead-free and ambient-stable materials for photovoltaic and optoelectronic applications. To advance these promising materials, it is crucial to determine the correlations between physical properties and their local structure and dynamics. Solid-state NMR spectroscopy of multiple NMR-active nuclei (<sup>133</sup>Cs, <sup>119</sup>Sn and <sup>35</sup>Cl) in these cesium tin(IV) halides has been used to decode the structure, which plays a key role in the materials’ optical properties. The <sup>119</sup>Sn NMR chemical shifts span approximately 4000 ppm and the <sup>119</sup>Sn spin-lattice relaxation times span three orders of magnitude when the halogen goes from chlorine to iodine in these diamagnetic compounds. Moreover, ultrawideline <sup>35</sup>Cl NMR spectroscopy for Cs<sub>2</sub>SnCl<sub>6</sub> indicates an axially symmetric chlorine electric field gradient tensor with a large quadrupolar coupling constant of <i>ca.</i> 32 MHz, suggesting a chlorine that is directly attached to Sn(IV) ions. Variable temperature <sup>119</sup>Sn spin lattice relaxation time measurements uncover the presence of hidden dynamics of octahedral SnI<sub>6</sub> units in Cs<sub>2</sub>SnI<sub>6</sub> with a low activation energy barrier of 12.45 kJ/mol (0.129 eV). We further show that complete mixed-halide solid solutions of Cs<sub>2</sub>SnCl<sub>x</sub>Br<sub>6−x</sub> and Cs<sub>2</sub>SnBr<sub>x</sub>I<sub>6−x</sub> (0 ≤ x ≤ 6) form at any halogen compositional ratio. <sup>119</sup>Sn and <sup>133</sup>Cs NMR spectroscopy resolve the unique local SnCl<i><sub>n</sub></i>Br<sub>6−<i>n</i></sub>and SnBr<i><sub>n</sub></i>I<sub>6−<i>n</i></sub> (<i>n</i> = 0−6) octahedral and CsBr<i><sub>m</sub></i>I<sub>12−<i>m</i></sub> (<i>m</i> = 0−12) cuboctahedral environments in the mixed-halide samples. The experimentally observed <sup>119</sup>Sn NMR results are consistent with magnetic shielding parameters obtained by density functional theory computations to verify random halogen distribution in mixed-halide analogues. Finally, we demonstrate the difference in the local structures and optical absorption properties of Cs<sub>2</sub>SnI<sub>6</sub> samples prepared by solvent-assisted and solvent-free synthesis routes.

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