(17)O NMR Investigation of Water Structure and Dynamics (original) (raw)
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Chemistry of Materials, 2015
A structural characterization of the hydrated form of the brownmilleritetype phase Ba 2 In 2 O 5 , Ba 2 In 2 O 4 (OH) 2 , is reported using experimental multinuclear NMR spectroscopy and density functional theory (DFT) energy and GIPAW NMR calculations. When the oxygen ions from H 2 O fill the inherent O vacancies of the brownmillerite structure, one of the water protons remains in the same layer (O3) while the second proton is located in the neighboring layer (O2) in sites with partial occupancies, as previously demonstrated by Jayaraman et al. (Solid State Ionics 2004, 170, 25−32) using Xray and neutron studies. Calculations of possible proton arrangements within the partially occupied layer of Ba 2 In 2 O 4 (OH) 2 yield a set of low energy structures; GIPAW NMR calculations on these configurations yield 1 H and 17 O chemical shifts and peak intensity ratios, which are then used to help assign the experimental MAS NMR spectra. Three distinct 1 H resonances in a 2:1:1 ratio are obtained experimentally, the most intense resonance being assigned to the proton in the O3 layer. The two weaker signals are due to O2 layer protons, one set hydrogen bonding to the O3 layer and the other hydrogen bonding alternately toward the O3 and O1 layers. 1 H magnetization exchange experiments reveal that all three resonances originate from protons in the same crystallographic phase, the protons exchanging with each other above approximately 150°C. Three distinct types of oxygen atoms are evident from the DFT GIPAW calculations bare oxygens (O), oxygens directly bonded to a proton (H-donor O), and oxygen ions that are hydrogen bonded to a proton (H-acceptor O). The 17 O calculated shifts and quadrupolar parameters are used to assign the experimental spectra, the assignments being confirmed by 1 H− 17 O double resonance experiments.
17O NMR of water in ordered environments
Biophysical Chemistry, 1998
Two NMR experiments are designed for selective excitation of spin I s 5r2 nuclei that exhibit residual quadrupolar splittings. The I s 5r2 Jeener᎐Broekaert experiment is preferred to the four-quantum filtration experiment as it is shown to be a more sensitive technique in experimental practice. Both techniques are applied to 17 O-enriched water in biological systems. The occurrence of water which displays a residual 17 O quadrupolar splitting is demonstrated for the first time in a model biological system and an excised tissue sample. The resulting 17 O NMR spectra are shown to have the characteristics predicted in computer-simulated I s 5r2 NMR spectra. ᮊ 1998 Elsevier Science B.V. All rights reserved.
Nuclear magnetic resonance parameters in water dimer
Theoretical Chemistry Accounts, 2011
The changes in the computed nuclear magnetic resonance (NMR) parameters of the water dimer with respect to their monomer values were monitored as the geometry of the dimer was systematically varied. Nuclear magnetic shielding constants, shielding tensor anisotropies, nuclear quadrupole coupling constants and spin-spin coupling constants for the hydrogen bond donor and acceptor molecules were calculated at hybrid density-functional theory level. The dimer geometry was specified through the intermolecular oxygen-oxygen distance R OO and the hydrogen bond angle a. A grid of 120 geometries was selected by systematically varying these two parameters. The other geometrical parameters of the dimer were allowed to relax, keeping the two parameters fixed. As the dimer geometry was varied, all NMR parameters were observed to be smoothly behaving. Characteristic changes as a function of the intermolecular geometry were observed. These include, besides the well-known deshielding of the donor hydrogen shielding constant, also influences on the donor deuterium quadrupole coupling constant, as well as the shielding anisotropy of the donor and acceptor oxygens. We discuss the contributions to the total dimerisation effect from, on the one hand, the dominant direct interaction effect at a fixed geometry and, on the other hand, from the quantitatively relevant indirect, geometric effect. A fundamental ambiguity of this partitioning is demonstrated. By forging the general, smooth trends in all the studied NMR parameters into a specific geometric definition, we find our data to be in agreement with the widely used distance criterion for hydrogen bonding in water, R OO B 3.5 Å .
Physical review. E, Statistical, nonlinear, and soft matter physics, 2002
A nuclear magnetic resonance study of protons and deuterons in the mesomorphic phases of the micellar lyotropic mixture potassium laurate/1-decanol/heavy water is reported. The slow dynamical behavior of water molecules has been investigated with deuterons spin-lattice relaxation dispersion in the Larmor frequency range 10(3)<nu(L)<4.2x10(7) Hz. In order to compare relative behaviors additional T1 dispersion of micellar protons has been measured in the same compound, temperature, and Larmor frequency range. From the experimental behaviors, we conclude that in the nematic phases the water slow reorientational dynamics is closely related to the slow reorientation of the micellar aggregates. In addition, conventional deuterium nuclear magnetic resonance at nu(L)=4.2x10(7) Hz spectra has been measured at different places in the phase diagram. The line shapes show a quadrupolar splitting in nematic phases, meanwhile in the isotropic phase the spectral structure collapses in a singl...
Journal of the American Chemical Society, 2012
We report a comprehensive variable-temperature solid-state 17 O NMR study of three 17 O-labeled crystalline sulfonic acids: 2-aminoethane-1-sulfonic acid (taurine, T), 3aminopropane-1-sulfonic acid (homotaurine, HT), and 4-aminobutane-1-sulfonic acid (ABSA). In the solid state, all three compounds exist as zwitterionic structures, NH 3 + −R−SO 3 − ,i n which the SO 3 − group is involved in various degrees of O•••H−N hydrogen bonding. High-quality 17 O NMR spectra have been obtained for all three compounds under both static and magic angle spinning (MAS) conditions at 21.1 T, allowing the complete set of 17 O NMR tensor parameters to be measured. Assignment of the observed 17 O NMR parameters to the correct oxygen sites in the crystal lattice was achieved with the aid of DFT calculations. By modeling the temperature dependence of 17 O NMR powder line shapes, we have not only confirmed that the SO 3 − groups in these compounds undergo a 3-fold rotational jump mechanism but also extracted the corresponding jump rates (10 2 −10 5 s −1) and the associated activation energies (E a) for this process (E a =4 8± 7, 42 ± 3, and 45 ± 1 kJ mol −1 for T, HT, and ABSA, respectively). This is the first time that SO 3 − rotational dynamics have been directly probed by solid-state 17 O NMR. Using the experimental activation energies for SO 3 − rotation, we were able to evaluate quantitatively the total hydrogen bond energy that each SO 3 − group is involved in within the crystal lattice. The activation energies also correlate with calculated rotational energy barriers. This work provides a clear illustration of the utility of solid-state 17 O NMR in quantifying dynamic processes occurring in organic solids. Similar studies applied to selectively 17 O-labeled biomolecules would appear to be very feasible.
Chemistry of materials : a publication of the American Chemical Society, 2015
A structural characterization of the hydrated form of the brownmillerite-type phase Ba2In2O5, Ba2In2O4(OH)2, is reported using experimental multinuclear NMR spectroscopy and density functional theory (DFT) energy and GIPAW NMR calculations. When the oxygen ions from H2O fill the inherent O vacancies of the brownmillerite structure, one of the water protons remains in the same layer (O3) while the second proton is located in the neighboring layer (O2) in sites with partial occupancies, as previously demonstrated by Jayaraman et al. (Solid State Ionics2004, 170, 25-32) using X-ray and neutron studies. Calculations of possible proton arrangements within the partially occupied layer of Ba2In2O4(OH)2 yield a set of low energy structures; GIPAW NMR calculations on these configurations yield (1)H and (17)O chemical shifts and peak intensity ratios, which are then used to help assign the experimental MAS NMR spectra. Three distinct (1)H resonances in a 2:1:1 ratio are obtained experimentall...
Vibrationally averaged magnetizabilities and rotational g tensors of the water molecule
1998
Using large basis sets, London atomic orbitals and large multiconfigurational self-consistent field wavefunctions, we have calculated the molecular magnetizability and rotational g tensors of the water molecule, including zero-point vibrational corrections. Whereas the vibrational corrections are found to be negligible for the magnetizability, the inclusion of Ž . vibrational effects being of the order of 2% makes our calculated rotational g tensor agree well with experimental observations for D O. For H O we show that earlier agreement between theory and experiment is fortuitous and arises from 2 2 the neglect of zero-point vibrational contributions in both approaches. We suggest that the rotational g tensor of H O and 2 HDO be remeasured. q 1998 Elsevier Science B.V. All rights reserved.