Structural and dynamical studies of the hydrate, exchangeable hydrogens, and included molecules in .beta.- and .gamma.-cyclodextrins by powder and single-crystal deuterium magnetic resonance

Highly Hydrated Cations: Deficiency, Mobility, and Coordination of Water in Crystalline Nonahydrated Scandium(III), Yttrium(III), and Lanthanoid(III) Trifluoromethanesulfonates

“…[41] Eventually, when the temperature is sufficiently high, the rate of this motion becomes fast (@ 10 5 s À1 ) on the 2 H NMR timescale and the relatively narrow powder pattern (feature c) emerges. In accordance with the assignments in previous investigations of hydrated solids, [42] we associate this feature with positional exchange of the water molecules.…”

Dipole relaxation and proton transport in polycrystalline γ-cyclodextrin hydrate: A dielectric spectroscopy study

“…The absolute values of τ vary between 6.1 μs and 7.7 μs in contrast to the case of β-CD hydrate in our previous investigation [23] where the values of τ were found to vary between 8.0 μs and 11.5 μs. This difference indicates that the water network presents a higher degree of disorder in γ-CD hydrate than in β-CD hydrate something that has already been proven by the detailed deuterium NMR study of both materials [50]. This work has further demonstrated reorientational rates that are comparable to those obtained from our dielectric data.…”

“…Moreover, it should be noted that according to the quasielastic neutron scattering study of β-CD·11H 2 O, the rates of both the rotational jumps and positional fluctuations in the crystal lattice range between 10 10 and 10 11 s − 1 [57]. The fact that in the current research the respective rates range between 10 5 and 10 6 s − 1 (correlating well with NMR experiments [50]) may be attributed to a coupling of fast local motions to slower collective ones [58].…”

“…As the authors report this means that a particular water molecule "experiences" many H-(or D)-transfer processes as it "travels" between adjacent asymmetric units. In relation to this, the in-depth solid state NMR investigations of β-CD hydrate by Ripmeester [35] as well as of β-and γ-CD hydrates by Usha and Wittebort [50] have proven that water diffuses through the crystal lattice by exchanging among symmetry related crystallographic positions. Therefore, in our case it appears to be explicit that by the initiation of the dehydration process (~301.0 K) the concomitant diffusional jumps of the water molecules between adjacent asymmetric units are highly correlated.…”

The Influence of Water Content on the 23Na and 31P NMR Spectral Parameters in Solid Na-DNA

“…Given the hydrophobic nature of DNA, in order to ensure the exact water content of the sample inside the NMR probehead, we monitored the spectral width of the 1 H line over a 12 h period. Constant linewidth indicates unchanged water content of the sample [21].…”