On the determination of the orientational probability distribution of water in heterogeneous systems from 2H and 17O quadrupolar splittings

Wong, Tuck C.; Hakala, Marja-Riitta

doi:10.1016/0009-2614(85)85425-7

Cited by 5 publications

(5 citation statements)

References 19 publications

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“…The quadrupolar splitting (Δ) of any given deuteron in the medium of a liquid crystalline phase can be related to the degree of orientation of its X-D bond (where X = C or O) with respect to the applied magnetic field direction, S XD , by eq (in which ( e 2 qQ/h ) is the deuteron quadrupolar coupling constant along the X-D bond, eQ is the electric quadrupole moment of a deuteron, and eq is the electric field gradient experienced by the deuteron) . The quadrupolar coupling constants of deuterons are 223 KHz for water, and 155 KHz for the methyl group of methanol (31 °C), 183 KHz for the methyl group and 177 KHz for the methylene group of ethanol (20−41 °C), and 170 KHz for the α-methylene groups of 1-propanol and 1-butanol . These constants vary slightly with temperature and are assumed to be constant throughout the temperature ranges explored here.…”

Section: Resultsmentioning

confidence: 99%

Room-Temperature and Low-Ordered, Amphotropic-Lyotropic Ionic Liquid Crystal Phases Induced by Alcohols in Phosphonium Halides

Shahkhatuni

Somashekhar

et al. 2008

Langmuir

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Tri- n-decylmethylphosphonium chloride and bromide ( 1P10X) salts are not liquid crystalline. However, mesophases are induced by adding very small amounts of an alcohol or water. The temperature ranges of the induced smectic A 2 (SmA 2) liquid-crystalline phases can be very broad and the onset temperatures can be below room temperature depending upon the concentration of the alcohol or water and the structure of the alcohol. At least one molar equivalent of hydroxyl groups is necessary to convert the 1P10X completely into a liquid crystal. Strong association between the hydroxyl groups of an alcohol or water and the head groups of the 1P10X is indicated by spectroscopic, diffraction, and thermochemical data. Unlike many other smectic phases, those of the 1P10X/alcohol complexes are easily aligned in strong magnetic fields and the order parameters of selectively deuterated alcohols as measured by (2)H NMR spectroscopy, approximately 10 (-2), are much lower than the values found when the host is a commonly employed thermotropic liquid crystal. The dependence of the specific values of the order parameters on temperature, the nature of the halide anion, and the structure and concentration of the alcohol are reported. In sum, a detailed picture is presented to explain how and why an alcohol or water induces liquid crystallinity in the 1P10X salts. The data also provide a blueprint for designing media with even lower order parameters that can be hosts to determine the conformations and shapes of guest molecules.

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Section: Resultsmentioning

confidence: 99%

Room-Temperature and Low-Ordered, Amphotropic-Lyotropic Ionic Liquid Crystal Phases Induced by Alcohols in Phosphonium Halides

Shahkhatuni

Somashekhar

et al. 2008

Langmuir

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“…Nuclear magnetic resonance is a powerful tool to analyze the ordering of suspensions of anisotropic particles, such as liquid crystals [1][2][3], colloids [4,5], polymers [6], polyelectrolytes [7], and bilayers [8,9], if a sensitive nuclear probe is embedded within the particle or strongly linked to its surface [5,8,10]. In this article, we suggest the measurement of the solvent self-diffusion tensor anisotropy to quantify the ordering of nematic dispersions of anisotropic particles when such sensitive magnetic nuclei is lacking.…”

mentioning

confidence: 99%

“…By contrast to the classical detection of nematic ordering by the splitting of the resonance line of some nucleus either included in the particle [1,3] or strongly coupled to its surface [5,8,10], this procedure simply requires a solvent with an easily detected isotope ( 1 H, 2 H, . .…”

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confidence: 99%

Anisotropy of the Solvent Self-Diffusion Tensor as a Probe of Nematic Ordering within Dispersions of Nanocomposites

et al. 2001

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“…The ratio of the 170 to the 2H quadrupolar splitting (Table 3) changed from a high orS.0 to a low ofzero--a remarkable finding. In earlier investigations of water ordering by liquid crystalline solutes (Wong and Hakala, 1985;Hakala and Wong, 1986), this ratio was invariant at about 6. In a recent paper (Guo and Wong, 1987) values as low as 2.1 were reported.…”

Section: H Splittings Are Listed Inmentioning

confidence: 86%

“…A rotating dipole, such as that of a water molecule, may be expected to point its positive end towards the negatively changed aluminosilicate sheet. To monitor such local orderings quadrupolar splittings of the deuterium (2H) nuclear magnetic resonance may be measured for deuterons in water molecules (Wong and Hakala, 1985;Hakala and Wong, 1986). Such splittings can be detected, if water molecules reside in non-isotropic environments.…”

Section: Introductionmentioning

confidence: 99%

Deuterium Nuclear Magnetic Resonance Studies of Water Molecules Restrained by Their Proximity to a Clay Surface

Grandjean

1989

Clays and clay miner.

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Abstract--Observation of quadrupolar splittings for 2H and 170 nuclei from D20 solvent molecules in suspensions of the Ecca Gum BP bentonite points unambiguously to the ordering of water molecules with respect to a static magnetic field. The application of the magnetic field apparently orients the clay platelets as tactoids. Some water molecules adhere to the platelets and are oriented. The magnitude of the quadrupolar splitting depends strongly on the nature of the interstitial cations. The sign of the splitting changes as the ratio of divalent to monovalent cation increases, reflecting a switch in the microdynamics of water molecules next to the plates. With the entry of divalent cations, the clay becomes more cohesive due to the vertical electrostatic attraction of the counterions to the charged plates. More of these hydrated divalent ions compared with monovalent ions condense onto the charged sheet, thereby increasing metal coordination to those water molecules in contact with the clay surface. The dominant reorientation mode of the water molecules switches from rotation of water molecules around hydrogen bonds to the charged sheets to rotation around the electrostatic bond to the divalent metal cation. The effect is spectacular and important in understanding the chemical properties of cation-exchanged montmorillonites.

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On the determination of the orientational probability distribution of water in heterogeneous systems from 2H and 17O quadrupolar splittings

Cited by 5 publications

References 19 publications

Room-Temperature and Low-Ordered, Amphotropic-Lyotropic Ionic Liquid Crystal Phases Induced by Alcohols in Phosphonium Halides

Room-Temperature and Low-Ordered, Amphotropic-Lyotropic Ionic Liquid Crystal Phases Induced by Alcohols in Phosphonium Halides

Anisotropy of the Solvent Self-Diffusion Tensor as a Probe of Nematic Ordering within Dispersions of Nanocomposites

Deuterium Nuclear Magnetic Resonance Studies of Water Molecules Restrained by Their Proximity to a Clay Surface

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