Anion reorientations and cation diffusion in a carbon-substituted sodium nido-borate Na-7,9-C2B9H12: 1H and 23Na NMR studies

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alexander V. Skripov ◽  
Olga A. Babanova ◽  
Roman V. Skoryunov ◽  
Alexei V. Soloninin ◽  
Terrence J. Udovic
Keyword(s):  
Lattice Relaxation ◽  
Activation Energies ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Cation Diffusion ◽  
Relaxation Data ◽  
Nmr Studies ◽  
Spin Lattice ◽  
Jump Rate ◽  
Disordered Phase

Abstract Polyhydroborate-based salts of lithium and sodium have attracted much recent interest as promising solid-state electrolytes for energy-related applications. A member of this family, sodium dicarba-nido-undecahydroborate Na-7,9-C2B9H12 exhibits superionic conductivity above its order-disorder phase transition temperature, ∼360 K. To investigate the dynamics of the anions and cations in this compound at the microscopic level, we have measured the 1H and 23Na nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation rates over the temperature range of 148–384 K. It has been found that the transition from the low-T ordered to the high-T disordered phase is accompanied by an abrupt, several-orders-of-magnitude acceleration of both the reorientational jump rate of the complex anions and the diffusive jump rate of Na+ cations. These results support the idea that reorientations of large [C2B9H12]− anions can facilitate cation diffusion and, thus, the ionic conductivity. The apparent activation energies for anion reorientations obtained from the 1H spin-lattice relaxation data are 314 meV for the ordered phase and 272 meV for the disordered phase. The activation energies for Na+ diffusive jumps derived from the 23Na spin-lattice relaxation data are 350 and 268 meV for the ordered and disordered phases, respectively.

An experimental evaluation of nonselective proton spin–lattice relaxation rates: analyses of data for the eight isomeric 2,3,4-tri-O-acetyl-1,6-anhydro-β-D-hexopyranoses

1980 ◽  
Vol 58 (18) ◽  
pp. 1916-1922 ◽  
Author(s):  
Klaus Bock ◽  
Laurance D. Hall ◽  
Christian Pedersen
Keyword(s):  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Pyranose Ring ◽  
Solvent Concentration ◽  
Relaxation Data ◽  
Spin Lattice ◽  
Single Set

The nonselective spin–lattice relaxation rates (R1-values) have been determined for all of the ring protons of the eight isomers of 2,3,4-tri-O-acetyl-1,6-anhydro-(β-D-hexopyranose as 0.1 molar solutions in benzene-d6. The effects on the proton R1-values of changes in solvent, concentration, temperature, and proton impurities are documented and 13C R1-values are given to show that the first two sets of variations are due to changes in motional correlation times of the molecules. The proton relaxation data can be fitted by regressional analyses to a single set of interproton relaxation contributions, the numerical values of which accord with a 1C4 conformation for the pyranose ring somewhat distorted by the 1,6-anhydro bridge.

NMR Studies on Intercalation Compounds of Layered Chalcogenides with Methylamines and Ammonia

1983 ◽  
Vol 38 (2) ◽  
pp. 237-246 ◽  
Author(s):  
M. Molitor ◽  
W. Müller-Warmuth ◽  
H. W. Spieß ◽  
R. Schöllhorn
Keyword(s):  
Lattice Relaxation ◽  
Intercalation Compounds ◽  
Spin Lattice Relaxation ◽  
Specific Information ◽  
Relaxation Rates ◽  
Nmr Studies ◽  
Layered Chalcogenides ◽  
Spin Lattice ◽  
Study Orientation ◽  
Niobium Disulfide

Abstract NMR wideline and pulse techniques have been used to study orientation and molecular motions of the intercalation compounds of niobium disulfide with monolayers of mono-, di-, and trimethylamine, tetramethylammonium and ammonia. Specific information has been obtained from the 1H and 2D spectra and from spin-lattice relaxation measurements of the selectively deuterated monomethylamines. Models for the arrangement of the various molecules within the layers and for the motions have been derived. One-dimensional rotation of CH3 and NH3 groups, rapid intermolecular exchange of NH, NH2 and NH3 protons, as well as translational and reorientational motions of whole molecules are of importance. Interpretation of spin-lattice relaxation rates at various temperatures and frequencies yields details of some of these motion and numerical values for the activation energies.

Relaxation and related 1H nmr studies on "asperlin." Configuration and conformation of the epoxypropyl side-chain

1985 ◽  
Vol 63 (5) ◽  
pp. 1009-1012 ◽  
Author(s):  
Photis Dais ◽  
Arthur S. Perlin
Keyword(s):  
1H Nmr ◽  
Benzene Solution ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Oxirane Ring ◽  
Side Chain ◽  
Relaxation Rates ◽  
Nmr Studies ◽  
Spin Lattice ◽  
Configuration And Conformation

Monoselective and biselective spin-lattice relaxation rates, together with nOe experiments, have been used to examine the configuration and conformation of the epoxypropyl side-chain of "asperlin" (1) in benzene solution. The data confirm earlier evidence that the oxirane ring is trans, and indicate that 1 is the 6R, 7S diastereomer. Moreover, it is shown that in the most probable conformation of the side-chain about the C-5, C-6 bond, H-5 and H-6 are anti.

2H and 14N NMR Studies of the Dynamics in the Incommensurate Phases of Betaine Calciumchloride Dihydrate

1995 ◽  
Vol 50 (4-5) ◽  
pp. 368-372 ◽  
Author(s):  
U. Häcker ◽  
D. Michel ◽  
K.-P. Hölzer ◽  
J. Petersson
Keyword(s):  
Low Frequency ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Nmr Studies ◽  
Spin Lattice ◽  
Modulated Phases ◽  
Soliton Lattice ◽  
Higher Spin ◽  
Incommensurate Phases

Abstract2H and 14N NMR spin-lattice relaxation rates were measured in the structurally incommensurately (IC) modulated phases of deuterated and undeuterated betaine calciumchloride dihydrate, respectively. The results are related to the elementary excitations of these phases. The presence of low-frequency phase fluctuations of the modulation wave leads to higher spin-lattice relaxation rates compared with the high-temperature normal phase and the commensurate (C) phases. The corresponding "phason" contributions are found to be nearly constant in the whole IC phases. In the IC phases near the transitions to the C phases the relaxation rates decrease due to the formation of the soliton lattice. This interpretation is in agreement with the results of previous dielectric measurements

NMR studies of alkali intercalted carbon nanotubes

2003 ◽  
Vol 772 ◽  
Author(s):  
M. Schmid ◽  
C. Goze-Bac ◽  
M. Mehring ◽  
S. Roth ◽  
P. Bernier
Keyword(s):  
Carbon Nanotubes ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Energy Storage Devices ◽  
Nmr Studies ◽  
Storage Devices ◽  
Spin Lattice ◽  
Relaxation Measurements ◽  
Resonance Spin ◽  
Walled Carbon Nanotubes

AbstractLithium intercalted carbon nanotubes have attracted considerable interest as perspective components for energy storage devices. We performed 13C Nuclear Magnetic Resonance spin lattice relaxation measurements in a temperature range from 4 K up to 300 on alkali intercalated Single Walled Carbon Nanotubes in order to investigate the modifications of the electronic properties. The density of states at the Fermi level were determined for pristine, lithium and cesium intercalated carbon nanotubes and are discussed in terms of intercalation and charge transfer effects.

Analysis of Spin Polarisation Transients in Periodically Photo-excited Triplet States

1975 ◽  
Vol 30 (5) ◽  
pp. 571-582 ◽  
Author(s):  
C. J. Winscom
Keyword(s):  
Lattice Relaxation ◽  
Rectangular Pulse ◽  
Decay Rates ◽  
Spin Lattice Relaxation ◽  
Pulse Excitation ◽  
Triplet States ◽  
Relaxation Rates ◽  
Spin Sublevel ◽  
Spin Lattice ◽  
The Individual

Abstract The behaviour of spin sublevel populations with time following periodic photo-excitation is ex-amined. The treatment is limited to conditions of magnetic field strength and temperature for which the spin lattice relaxation rates dominate the individual spin sublevel decay rates. The response of the system to three modes of excitation is considered: (i) continuous excitation using a time-independent intensity (ii) periodic rectangular pulse excitation and (iii) periodic waveform excitation. A convenient correspondence between the various forms of solutions is pointed out. The requirements of an experiment to determine spin-lattice relaxation rates in organic triplets at 77 K are discussed.

An experimental evaluation of simplified procedures for determining the proton spin–lattice relaxation rates of natural products

1980 ◽  
Vol 58 (19) ◽  
pp. 2016-2023 ◽  
Author(s):  
Lawrence D. Colebrook ◽  
Laurance D. Hall
Keyword(s):  
Natural Products ◽  
Lattice Relaxation ◽  
Null Point ◽  
Proton Spin ◽  
Computational Method ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Spin Lattice ◽  
Simplified Procedures

A general discussion is given of the determination of the proton spin–lattice relaxation rates of natural products, with particular emphasis on use of the null-point method which, for the systems studied here, gives identical results with those obtained via the conventional (and relatively time consuming) computational method.

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