Deuteron Spin -Lattice Relaxation Times in Undercooled Aqueous Potassium - and Cesium Halide Solutions

Fink, William H.; Radkowitsch, H.; Lang, Elmar

doi:10.1515/zna-1988-0604

Cited by 14 publications

(3 citation statements)

References 16 publications

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“…This is fairly well demonstrated in Fig. 1 which compares the pressure and concentration dependence of a low temperature 2 H-r, isotherm of NaCl and KC1 dissolved in D 2 0 [14,15].…”

Section: Orientational Fluctuations Of Water Molecules In the Hydrogesupporting

confidence: 61%

Multi-Nuclear Relaxation Time Studies in Undercooled Aqueous Electrolytes

Lang

Fink

Radkowitsch

et al. 1991

Hydrogen-Bonded Liquids

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“…This is fairly well demonstrated in Fig. 1 which compares the pressure and concentration dependence of a low temperature 2 H-r, isotherm of NaCl and KC1 dissolved in D 2 0 [14,15].…”

Section: Orientational Fluctuations Of Water Molecules In the Hydrogesupporting

confidence: 61%

Multi-Nuclear Relaxation Time Studies in Undercooled Aqueous Electrolytes

Lang

Fink

Radkowitsch

et al. 1991

Hydrogen-Bonded Liquids

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“…Though the effect is similar to dissolved Li+ ions, it is not due to strong ion-dipole interactions as in the latter case.33 •34 It has been shown earlier1 that the average mobility of water molecules becomes less hindered with decreasing charge density of dissolved atomic ions and finally is facilitated by large monovalent atomic ions like K+ and Cs+. 37 Though the charge density is further reduced in ß4 + ions, they hinder rotational and translational motions of water molecules rather than facilitate them. This slowing down must therefore be a consequence of a reduction in phase space of the coordinated water molecules caused by interactions with the apolar surface of the organic ions as has been correctly stated already by Zeidler and Hertz,45 who gave the term "hydration of the second kind" to these phenomena.…”

Section: Discussionmentioning

confidence: 99%

Hydration water dynamics in undercooled aqueous solutions of hydrophobic ions

Bradl¹,

Lang²

1993

J. Phys. Chem.

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Deuterium spin-lattice relaxation times (zH T I ) are reported for the first time as a function of temperature (180-300 K), pressure (p I 225 MPa), and composition (c I 5 m) in undercooled aqueous solutions of tetraalkylammonium ions (R4N+). A comparison with related investigations of undercooled alkali-metal halide solutions allows the competing influence of coulombic, hydrophobic, and H-bond interactions upon the dynamic structure of the random, transient H-bond network to be studied. Solvent dynamics are seen to be closely related to the glass-forming tendency of undercooled tetramethylammonium (Me4N+) and tetrapropylammonium (Pr4N+) bromide solutions and to the clathrate-forming tendency of undercooled tetrabutylammonium (Bu4N+) bromide solutions.

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“…4 we draw the following conclusions. K+ (radius, 1.38 A), which is a chaotrope (water-structure breaker) as judged by thermodynamic (10,11,14), transport (12,13), viscosity (25), NMR (26), infrared spectroscopy (27), and neutron diffraction (16) (10,11,14), transport (12,13), viscosity (25), infrared spectroscopy (27), and x-ray diffraction (16) data, when chromatographed as the Cl-salt is eluted in the position expected for Cl-(which adsorbs weakly to the nonpolar surface of Sephadex G-10), thus confirming that the effect of Na+ on water structure is small and demonstrating that the anion dominates the chromatographic behavior of the neutral salt. Li+ (radius, 0.74 A), in contrast, which is a polar kosmotrope as judged by thermodynamic (10,11,14), transport (12,13), viscosity (25), infrared spectroscopy (27), and neutron diffraction (16) data and has a substantial effect on water structure for a monovalent cation, does not adsorb to the nonpolar surface of Sephadex G-10.…”

Section: Methodsmentioning

confidence: 99%

Sticky ions in biological systems.

Collins

1995

Proc. Natl. Acad. Sci. U.S.A.

337

284

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Continuum electrostatics utilizes a macroscopic dielectric constant to characterize the ability of a medium to attenuate an electric field and has been developed to a level of great sophistication in application to biological systems (1-3). But even apart from its neglect of microscopic detail and the incorporation of a number of questionable assumptions-for example, that the free energy of solvation will be the same for anions and cations of the same size and absolute charge (2)-there is a realization that continuum electrostatics gives an incomplete accounting of the forces acting on ions in aqueous solution. As a result, in calculating the free energy of processes in aqueous solution, terms must be added which reflect the cohesive force of water resulting from the strong interactions between water molecules (1, 4). This cohesive force of water may be expressed by using the macroscopic concept of a surface tension, which tends to minimize the water-exposed surface area of dissolved species or interfacial surfaces. This opposes the repulsive "image force" between an ion in a region of high dielectric constant and the surface of a nearby region of lower dielectric constant which results from the preference of the electric field of the ion to remain in the region of high dielectric constant (5-9). The image repulsion of a partially hydrated monovalent ion of radius 1.6 A in direct contact with a nonpolar surface is about kT relative to the bulk solution (5) and decreases with increasing ion size. The surfaceThe publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. tension "pushing" a nonpolar sphere of this size onto a nonpolar surface is of comparable magnitude, and the surface tension effect inereases with increasing sphere size (1, 4). These considerations suggest that monovalent ions of about 1.6 A and larger should adsorb to nonpolar surfaces independent of any attractive forces between the ion and the nonpolar surface, whereas those smaller than about 1.6 A should be repelled from nonpolar surfaces. Similar predictions can be made from a microscopic perspective by comparing the entropy of water molecules near monovalent ions to that of water molecules in bulk solution as determined by thermodynamic (10,11,14) and transport (12, 13) data or dynamic measures such as NMR (15). Fig. 1 plots the entropy of water near monovalent ions as calculated from the entropy of hydration of the ion (from dissolving the ion in water) versus the ionic radius of the ion (11). A negative AS,, (upper portion of Fig. 1) indicates tightly bound water that is less mobile than bulk water, whereas a positive AS,, (lower portion of Fig. 1) indicates loosely held water that is more mobile than bulk water. Increasing ion size (decreasing ion charge density) is associated with increasing mobility of nearby water molecules. If this mobile, loosely held water is immediately adjacent...

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Deuteron Spin -Lattice Relaxation Times in Undercooled Aqueous Potassium - and Cesium Halide Solutions

Cited by 14 publications

References 16 publications

Multi-Nuclear Relaxation Time Studies in Undercooled Aqueous Electrolytes

Multi-Nuclear Relaxation Time Studies in Undercooled Aqueous Electrolytes

Hydration water dynamics in undercooled aqueous solutions of hydrophobic ions

Sticky ions in biological systems.

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