Ein Wasserstoffisotopieeffekt im CuSO4 * 5H2O

Abstract There are two kinds of water in CuSO4·5H2O differing by their binding in the crystal. The oxygen of four water molecules is bonded to the copper ion, that of the fifth molecule is hydrogen bonded. It is shown that the D/H ratios of these two kinds of water differ by 5.7%, the light isotope being enriched in the water molecules coordinated with the copper ion. The results show that there is no exchange of the hydrogen isotopes during the time needed for dehydration at room temperature which takes several days. The assumption has been confirmed that the water coordinated with the copper ion leaves the crystal first on dehydration at temperatures below 50 °C. Additional measurements of the separation factor for the hydrogen isotopes between water vapor and copper sulfate solutions allow conclusions on the fractionation of the hydrogen isotopes between bulk water and hydration water in aqueous solutions.

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Isotopieeffekte in den Hydratstrukturen von festem und gelöstem Kupfersulfat / Isotope effects in the hydrated structure of solid and aqueous copper sulphate

Zeitschrift für Naturforschung A ◽

10.1515/zna-1972-0518 ◽

1972 ◽

Vol 27 (5) ◽

pp. 819-826 ◽

Cited By ~ 12

Author(s):

B Maiwald ◽

K Heinzinger

Keyword(s):

Copper Sulphate ◽

Isotope Effects ◽

Copper Ion ◽

Hydrogen Isotopes ◽

Bulk Water ◽

Water Molecules ◽

Hydrogen Atoms ◽

Copper Sulphate Solution ◽

Crystal Water ◽

Lone Pairs

The fractionation of the oxygen isotopes of the water molecules in CuS04-5 H20 and in aqueous solutions of copper sulphate has been measured at 25 °C. In the total crystal water (G) three kinds of water can be distinguished by their binding: 1) The bisector of the two lone pairs directed towards the copper ion (Kj), 2) One of the lone pairs directed towards the copper ion (K2), 3) The two lone pairs directed towards two hydrogen atoms of water molecules coordinated with the copper ion (L). The water molecules in the copper sulphate solution are considered either hydration water (HW) or bulk water (FW). Defining a.\-B= (180/160)a/(180/180)b the following results have been obtained:There remains some doubt if the values attributed to ctKi-G and aK2-G have to be interchanged. The elementary cell of CuS04*5 H20 consists of two molecules. Four molecules of Kj-water are coordinated with one copper ion and four molecules of K2-water are coordinated with the second copper ion. The remaining two water molecules are of L-type. It is concluded from the results that on dehydration at temperatures below 50 °C first one copper ion loses it’s water and then the other. There is some doubt as to which group breaks up first. In addition, the results show that the L-type water becomes quantitatively the water of the monohydrate in agreement with the conclusions drawn from the results of the fractionation of the hydrogen isotopes in CuS04-5 H20. It is demonstrated that, by considering only the overall fractionation of the oxygen or hydrogen isotopes between total crystal water and the saturated solution, wrong conclusions about the crystallization process could be drawn. In the case of CuCl2 solutions, it has been shown that the separation factor aHW-FW is sensitive towards changes in the structure of the solution.

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Oxygen and Hydrogen Isotopic Preference in Hydration Spheres of Magnesium and Calcium Ions

Zeitschrift für Naturforschung A ◽

10.5560/zna.2012-0122 ◽

2013 ◽

Vol 68 (5) ◽

pp. 362-370 ◽

Cited By ~ 7

Author(s):

Takao Oi ◽

Kunihiko Sato ◽

Kazuki Umemoto

Keyword(s):

Partition Function ◽

Aqueous Solutions ◽

Molecular Orbital ◽

Oxygen Isotopes ◽

Calcium Ions ◽

Hydrogen Isotopes ◽

Bulk Water ◽

Water Molecules ◽

Molecular Orbital Calculations ◽

Hydration Sphere

Molecular orbital calculations were performed to estimate the 18O/16O and D/H isotopic reduced partition function ratios (rpfrs) of water molecules around magnesium and calcium ions. As model for water molecules in the ith hydration sphere of the cation in aqueous solutions containing that cation, we considered water molecules in the ith hydration sphere that were surrounded by water molecules in the (i+1)th hydration sphere in clusters, M2+(H2O)n (M = Mg or Ca; n up to 100). The calculations indicated that the decreasing order of the 18O preference over 16O in the primary hydration sphere is Mg2+ > Ca2+ > bulk water. That is, water molecules in the primary hydration spheres of the Mg2+ and Ca2+ ions are expected to be enriched in the heavier isotope of oxygen relative to water molecules in bulk, and the degree of the enrichment is larger for the Mg2+ ion than for the Ca2+ ion. No such preference was observed for hydrogen isotopes in any hydration sphere or for oxygen isotopes in the secondary and outer hydration spheres.

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Molecular Dynamics Study of a KCl Aqueous Solution: Dynamical Results

Zeitschrift für Naturforschung A ◽

10.1515/zna-1987-0302 ◽

1987 ◽

Vol 42 (3) ◽

pp. 227-230 ◽

Cited By ~ 5

Author(s):

M. Migliore ◽

S. L. Fornili ◽

E. Spohr ◽

K. Heinzinger

Keyword(s):

Diffusion Coefficients ◽

Md Simulation ◽

Bulk Water ◽

Water Molecules ◽

Hydration Water ◽

Self Diffusion ◽

Average Temperature ◽

Velocity Autocorrelation ◽

Dynamical Properties ◽

Velocity Autocorrelation Functions

In this paper we report on dynamical properties of a 2.2 molal aqueous KCl solution as obtained from an 8.7 ps MD simulation at an average temperature of 289 K. Velocity autocorrelation functions, self-diffusion coefficients and spectral densities of the hindered translational and librational motions of the ions and the water molecules assigned to three subsystems - hydration water of the cations, hydration water of the anions and bulk water - are discussed.

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Oxygen isotope separation factor at equilibrium of water vapor with basic aqueous solutions

Soviet Atomic Energy ◽

10.1007/bf01235492 ◽

1970 ◽

Vol 28 (1) ◽

pp. 56-56

Author(s):

L. B. Preobrazhenskaya ◽

E. S. Nedumova ◽

Ya. D. Zel'venskii

Keyword(s):

Water Vapor ◽

Aqueous Solutions ◽

Oxygen Isotope ◽

Separation Factor ◽

Isotope Separation

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Brillouin Neutron Spectroscopy as a Probe to Investigate Collective Density Fluctuations in Biomolecules Hydration Water

Spectroscopy An International Journal ◽

10.1155/2012/671265 ◽

2012 ◽

Vol 27 ◽

pp. 293-305 ◽

Cited By ~ 7

Author(s):

D. Russo ◽

A. Orecchini ◽

A. De Francesco ◽

F. Formisano ◽

A. Laloni ◽

...

Keyword(s):

Diffusion Processes ◽

Terahertz Spectroscopy ◽

Bulk Water ◽

Density Fluctuations ◽

Water Molecules ◽

Relaxation Processes ◽

Hydration Water ◽

Solvent Interaction ◽

Biological Functionality

The role of water in the behaviour of biomolecules is well recognized. The coupling of motions between water and biomolecules has been studied in a wide time scale for theselfpart whilecollectivedynamics is still quite unexplored.Self-dynamics provides information about the diffusion processes of water molecules and relaxation processes of the protein structure.Collectivedensity fluctuations might provide important insight on the transmission of information possibly correlated to biological functionality. The idea that hydration water layers surrounding a biological molecule show aself-dynamical signature that differs appreciably from that of bulk water, in analogy with glass-former systems, is quite accepted. In the same picture Brillouin terahertz spectroscopy has been used to directly probecollectivedynamics of hydration water molecules around biosystems, showing a weaker coupling and a more bulklike behaviour. We will discuss results of collective modes of hydration water, arising from neutron Brillouin spectroscopy, in the context of biomolecules-solvent interaction.

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Struktur und Schwingungsspektrum des Tetraguanidiniumditellurats, [C(NH2)3]4Te2O6(0H)4 / Structure and Vibrational Spectrum of Guanidiniumditellurate, [C(NH2)3]4Te2O6(0H)4

Zeitschrift für Naturforschung B ◽

10.1515/znb-1982-0511 ◽

1982 ◽

Vol 37 (5) ◽

pp. 587-593 ◽

Cited By ~ 7

Author(s):

Joachim Fuchs ◽

Reinhard Loederich ◽

Joachim Pickardt

Keyword(s):

Aqueous Solution ◽

Raman Spectrum ◽

Vibrational Spectrum ◽

Aqueous Solutions ◽

Potassium Salt ◽

Room Temperature ◽

Unit Cell ◽

Water Molecules ◽

Guanidinium Salt ◽

Oxygen Atoms

Guanidiniumditellurate obtained from aqueous solution at room temperature forms triclinic crystals of space group P1̄ with lattice parameters a = 17.486(4) Å, b = 8.459(7) Å, c = 7.134(8) Å; a = 107.42(2)°, β = 83.95(2)° and y = 103.14(2)°. The unit cell contains two crystallographically independent anions with symmetry centers at 0, 0, 0 and 1/2, 0, 1/2. They consist of two octahedral TeO4(OH)2 units which share two common oxygen atoms. The guanidinium ions are connected over an irregular network of bridging hydrogens and terminal oxygen atoms of the anions, in similar manner as ditellurate ions are joined by water molecules in aqueous solutions: the Raman spectrum of the guanidinium salt is nearly identical with the solution spectrum of a ditellurate, but exhibits pronounced differences regarding the spectrum of the solid potassium salt K4Te2O6(OH)2 • 7 H2O

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Local Dynamics of the Hydration Water and Poly(Methyl Methacrylate) Chains in PMMA Networks

Frontiers in Chemistry ◽

10.3389/fchem.2021.728738 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yoshihisa Fujii ◽

Taiki Tominaga ◽

Daiki Murakami ◽

Masaru Tanaka ◽

Hideki Seto

Keyword(s):

Methyl Methacrylate ◽

Bulk Water ◽

Polymer Chains ◽

Water Molecules ◽

Hydration Water ◽

Segmental Motion ◽

Local Motion ◽

Deuterium Labeling ◽

Elastic Neutron ◽

Poly Methyl Methacrylate

The dynamic behavior of water molecules and polymer chains in a hydrated poly(methyl methacrylate) (PMMA) matrix containing a small amount of water molecules was investigated. Water molecules have been widely recognized as plasticizers for activating the segmental motion of polymer chains owing to their ability to reduce the glass transition temperature. In this study, combined with judicious hydrogen/deuterium labeling, we conducted quasi-elastic neutron scattering (QENS) experiments on PMMA for its dry and hydrated states. Our results clearly indicate that the dynamics of hydrated polymer chains are accelerated, and that individual water molecules are slower than bulk water. It is therefore suggested that the hydration water affects the local motion of PMMA and activates the local relaxation process known as restricted rotation, which is widely accepted to be generally insensitive to changes in the microenvironment.

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Hydration Chamber for Jeolco 200 Kv Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069703 ◽

1970 ◽

Vol 28 ◽

pp. 542-543

Author(s):

V. R. Matricardi ◽

G. G. Hausner ◽

D. F. Parsons

Keyword(s):

Electron Microscope ◽

Water Vapor ◽

Vapor Pressure ◽

Pressure Gradient ◽

Room Temperature ◽

List Type ◽

Type Number ◽

Equilibrium Vapor Pressure

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied: The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.

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Warm and freeze-fracture of cotton seed radicles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129206 ◽

1987 ◽

Vol 45 ◽

pp. 984-985

Author(s):

E. L. Vigil ◽

E. F. Erbe

Keyword(s):

Thin Film ◽

Water Vapor ◽

Fracture Surface ◽

Membrane Structure ◽

Room Temperature ◽

Freeze Fracture ◽

Longitudinal Axis ◽

Fracture Plane ◽

Cotton Seeds ◽

Condensed Water

In cotton seeds the radicle has 12% moisture content which makes it possible to prepare freeze-fracture replicas without fixation or cryoprotection. For this study we have examined replicas of unfixed radicle tissue fractured at room temperature to obtain data on organelle and membrane structure.Excised radicles from seeds of cotton (Gossyplum hirsutum L. M-8) were fractured at room temperature along the longitudinal axis. The fracture was initiated by spliting the basal end of the excised radicle with a razor. This procedure produced a fracture through the tissue along an unknown fracture plane. The warm fractured radicle halves were placed on a thin film of 100% glycerol on a flat brass cap with fracture surface up. The cap was rapidly plunged into liquid nitrogen and transferred to a freeze- etch unit. The sample was etched for 3 min at -95°C to remove any condensed water vapor and then cooled to -150°C for platinum/carbon evaporation.

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