scholarly journals Anesthetic Gases and Water Structure

1968 ◽  
Vol 52 (6) ◽  
pp. 876-886 ◽  
Author(s):  
Eugene Y. Berger ◽  
F. Rene Pecikyan ◽  
Grace Kanzaki
Keyword(s):  
Tritiated Water ◽  
Water Flux ◽  
Water Structure ◽  
Water Molecules ◽  
Crystal Formation ◽  
Self Diffusion ◽  
Average Water ◽  
Anesthetic Gases ◽  
Hydrate Crystal ◽  
Hydrogen Bonded

Pauling and Miller have independently proposed that the presence of an anesthetic gas in tissue induces a cage-like arrangement of hydrogen-bonded water molecules. The theories recognize that most gas-hydrate crystals would not form at the temperature and pressure that exist during anesthesia and propose that other components of tissue such as protein should have a stabilizing effect. Measurements of the behavior of water, rather than the anesthetic agent, would provide alternative information about the likelihood of hydrate crystal formation and this information could be such as to be applicable to body temperature and to pressures used for anesthesia. If the number of hydrogen-bonded water molecules in tissue is increased, then the movement of an average water molecule should be hindered. Movement of water through the tissue may be measured by tagging it with tritium and the anesthetic gas should then slow the movement of tritiated water through the tissue. The flux of tritiated water through rat cecum is indeed slowed when the cecum is exposed to the anesthetic gas, xenon, which can participate biochemically only by virtue of its van der Waals interaction. The decrement in water flux is in reasonable agreement with what could be expected theoretically from calculations based on the activation energy for the self-diffusion of water and the degree of hypothermia necessary to produce narcosis.

scholarly journals Microscopic Structural Features of Water in Aqueous-Reline Mixture of Varying Composition

2020 ◽  
Author(s):  
Soham Sarkar ◽  
Atanu Maity ◽  
Rajarshi Chakrabarti
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Choline Chloride ◽  
Bond Formation ◽  
Orientational Order ◽  
Water Structure ◽  
Structural Features ◽  
Water Molecules ◽  
Hydrogen Bond Formation ◽  
Hydrogen Bonded

Reline, a mixture of urea and choline chloride in 2:1 molar ratio, is one of the most frequently used deep eutectic solvents. Pure reline and its aqueous solution have large scale industrial use. Owing to the presence of active hydrogen bond formation sites, urea and choline cation can disrupt the hydrogen-bonded network in water. However, a quantitative understanding of the microscopic structural features of water in the presence of reline is still lacking. We use extensive all-atom molecular dynamics simulations to elucidate the effect of the gradual addition of co-solvents on microscopic arrangements of water molecules. We consider four aqueous solutions of reline, between the wt% 26.3 to 91.4. A disruption of the local hydrogen-bonded water structure is observed on inclusion of urea and choline chloride. The extent of deviation of water structure from tetrahedrality is quantified using the orientational order parameter. Our analyses show a monotonic increase in structural disorder as the co-solvents are added. Increment in the values are observed when highly electro-negative hetero-atoms like Nitrogen, Oxygen of urea and choline cations are counted as the partners of the central water molecules. Further insights are drawn from the characterization of the hydrogen-bonded network of the water and we observe gradual rupturing of water-water hydrogen bonds and its subsequent replacement by the water-urea hydrogen bonds. A negligible contribution from the hydrogen bonds between water and bulky choline cation has also been found. Considering all the constituents as the hydrogen bond partner we calculate the possibility of successful hydrogen bond formation with a central water molecule. This gives a clear picture of the underlying mechanism of water replacement by urea.

scholarly journals Microscopic Structural Features of Water in Aqueous-Reline Mixture of Varying Composition

2020 ◽  
Author(s):  
Soham Sarkar ◽  
Atanu Maity ◽  
Rajarshi Chakrabarti
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Choline Chloride ◽  
Bond Formation ◽  
Orientational Order ◽  
Water Structure ◽  
Structural Features ◽  
Water Molecules ◽  
Hydrogen Bond Formation ◽  
Hydrogen Bonded

Reline, a mixture of urea and choline chloride in 2:1 molar ratio, is one of the most frequently used deep eutectic solvents. Pure reline and its aqueous solution have large scale industrial use. Owing to the presence of active hydrogen bond formation sites, urea and choline cation can disrupt the hydrogen-bonded network in water. However, a quantitative understanding of the microscopic structural features of water in the presence of reline is still lacking. We use extensive all-atom molecular dynamics simulations to elucidate the effect of the gradual addition of co-solvents on microscopic arrangements of water molecules. We consider four aqueous solutions of reline, between the wt% 26.3 to 91.4. A disruption of the local hydrogen-bonded water structure is observed on inclusion of urea and choline chloride. The extent of deviation of water structure from tetrahedrality is quantified using the orientational order parameter. Our analyses show a monotonic increase in structural disorder as the co-solvents are added. Increment in the values are observed when highly electro-negative hetero-atoms like Nitrogen, Oxygen of urea and choline cations are counted as the partners of the central water molecules. Further insights are drawn from the characterization of the hydrogen-bonded network of the water and we observe gradual rupturing of water-water hydrogen bonds and its subsequent replacement by the water-urea hydrogen bonds. A negligible contribution from the hydrogen bonds between water and bulky choline cation has also been found. Considering all the constituents as the hydrogen bond partner we calculate the possibility of successful hydrogen bond formation with a central water molecule. This gives a clear picture of the underlying mechanism of water replacement by urea.

Understanding water structure from Raman spectra of isotopic substitution H2O/D2O up to 573 K

2017 ◽  
Vol 19 (32) ◽  
pp. 21540-21547 ◽  
Author(s):  
Qingcheng Hu ◽  
Haiwen Zhao ◽  
Shunli Ouyang
Keyword(s):  
Hydrogen Bonding ◽  
Raman Spectra ◽  
Water Structure ◽  
Free Water ◽  
Isotopic Substitution ◽  
Structure Model ◽  
Single Donor ◽  
Hydrogen Bonded

The OH/OD stretch band features on Raman spectra of isotopic substitution H2O/D2O at temperatures up to 573 K are correlated with a multi-structure model that water has five dominant hydrogen bonding configurations: tetrahedral, deformed tetrahedral, single donor, single hydrogen bonded water and free water.

scholarly journals Cyclooctanaminium hydrogen succinate monohydrate

2012 ◽  
Vol 68 (4) ◽  
pp. o1204-o1204 ◽  
Author(s):  
Sanaz Khorasani ◽  
Manuel A. Fernandes
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecule ◽  
Ammonium Cation ◽  
Water Molecules ◽  
Hydrated Salt ◽  
A Chain ◽  
Hydrogen Bonded

In the title hydrated salt, C8H18N+·C4H5O4−·H2O, the cyclooctyl ring of the cation is disordered over two positions in a 0.833 (3):0.167 (3) ratio. The structure contains various O—H.·O and N—H...O interactions, forming a hydrogen-bonded layer of molecules perpendicular to thecaxis. In each layer, the ammonium cation hydrogen bonds to two hydrogen succinate anions and one water molecule. Each hydrogen succinate anion hydrogen bonds to neighbouring anions, forming a chain of molecules along thebaxis. In addition, each hydrogen succinate anion hydrogen bonds to two water molecules and the ammonium cation.

Motions of water molecules in dilute aqueous solutions of tertiary butyl alcohol; a neutron scattering study of hydrophobic hydration

1970 ◽  
Vol 319 (1537) ◽  
pp. 189-208 ◽  
Keyword(s):  
Aqueous Solutions ◽  
Water Structure ◽  
Hydrophobic Hydration ◽  
Step Length ◽  
Solute Concentration ◽  
Butyl Alcohol ◽  
Tertiary Butyl ◽  
Self Diffusion ◽  
Dilute Aqueous Solutions ◽  
Neutron Scattering Study

Cold neutron inelastic scattering experiments have been performed on dilute aqueous solutions of (CD 3 ) 3 COH and of solutions of (CH 3 ) 3 COH in D 2 O at 21 °C. From the broadening of the quasi-elastic peak and independently determined self-diffusion coefficients ( D ), diffusive lifetimes ( c ) of H 2 O molecules have been calculated as functions of solute concentration. The product Dc is insensitive to concentration, giving a mean diffusion step length of 0.14 nm. The inelastic portion of the spectrum, reflecting lattice-like hydrogen bonding modes indicates that the solute enhances the water ‘structure’ but that such structure bears no resemblance to ice.

scholarly journals Molecular Dynamics Study on the Reverse Osmosis Using Multilayer Porous Graphene Membranes

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 805 ◽  
Author(s):  
Zhongqiang Zhang ◽  
Fujian Zhang ◽  
Zhen Liu ◽  
Guanggui Cheng ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Salt Solution ◽  
Energy Barrier ◽  
Water Flux ◽  
Solution Concentration ◽  
Water Molecules ◽  
Porous Graphene ◽  
Salt Rejection ◽  
Layer Separation ◽  
Graphene Membrane ◽  
Graphene Membranes

In this study, the reverse osmosis (RO) of a salt solution was investigated using a molecular dynamics method to explore the performance of a multilayer porous graphene membrane. The effects of the salt solution concentration, pressure, layer separation and pore offset on the RO performance of the membrane were investigated and the influences of the number of layers and the gradient structure were determined. The results show that as the salt solution concentration increases, the energy barrier of the water molecules passing through the bilayer porous graphene membranes changes slightly, indicating that the effect of the water flux on the membrane can be ignored. The salt rejection performance of the membrane improves with an increase in the concentration of the salt solution. When the pressure is increased, the energy barrier decreases, the water flux increases and the salt rejection decreases. When the layer separation of the bilayer porous graphene membrane is the same as the equilibrium spacing of the graphene membrane, the energy barrier is the lowest and the membrane water flux is the largest. The energy barrier of the bilayer porous graphene membrane increases with increasing layer separation, resulting in a decrease in the water flux of the membrane. The salt rejection increases with increasing layer separation. The water flux of the membrane decreases as the energy barrier increases with increasing pore offset and the salt rejection increases. The energy barrier effect is more pronounced for a larger number of graphene layers and the water flux of the membrane decreases because it is more difficult for the water molecules to pass through the porous graphene membrane. However, the salt rejection performance improves with the increase in the number of layers. The gradient pore structure enhances the energy barrier effect of the water molecules permeating through the membrane and the water flux of the membrane decreases. The salt rejection performance is improved by the gradient pore structure. The research results provide theoretical guidance for research on the RO performance of porous graphene membranes and the design of porous graphene membranes.

Syntheses and crystal structures of two magnesium–tetrazole compounds in salt and polymeric forms

2015 ◽  
Vol 71 (3) ◽  
pp. 222-228 ◽  
Author(s):  
Mohamed Abdellatif Bensegueni ◽  
Aouatef Cherouana ◽  
Slimane Dahaoui
Keyword(s):  
Alkaline Earth ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Magnesium Ion ◽  
Water Molecules ◽  
Compound I ◽  
Hydrothermal Conditions ◽  
One Dimensional ◽  
Polymeric Chains ◽  
Hydrogen Bonded

Two alkaline earth–tetrazole compounds, namelycatena-poly[[[triaquamagnesium(II)]-μ-5,5′-(azanediyl)ditetrazolato-κ3N1,N1′:N5] hemi{bis[μ-5,5′-(azanediyl)ditetrazolato-κ3N1,N1′:N2]bis[triaquamagnesium(II)]} monohydrate], {[Mg(C2HN9)(H2O)3][Mg2(C2HN9)2(H2O)6]0.5·H2O}n, (I), and bis[5-(pyrazin-2-yl)tetrazolate] hexaaquamagnesium(II), (C5H3N6)[Mg(H2O)6], (II), have been prepared under hydrothermal conditions. Compound (I) is a mixed dimer–polymer based on magnesium ion centres and can be regarded as the first example of a magnesium–tetrazolate polymer in the crystalline form. The structure shows a complex three-dimensional hydrogen-bonded network that involves magnesium–tetrazolate dimers, solvent water molecules and one-dimensional magnesium–tetrazolate polymeric chains. The intrinsic cohesion in the polymer chains is ensured by N—H...N hydrogen bonds, which formR22(7) rings, thus reinforcing the propagation of the polymer chain along theaaxis. The crystal structure of magnesium tetrazole salt (II) reveals a mixed ribbon of hydrogen-bonded rings, of typesR22(7),R22(9) andR24(10), running along thecaxis, which are linked byR24(16) rings, generating a 4,8-cflunet.

scholarly journals ELECTRO-OSMOTIC FRACTIONATION OF HYDROGEN ISOTOPES IN ELECTROLYTIC SOLUTIONS USING COMPOSITE PROTON-PERMEABLE MEMBRANES

2021 ◽  
pp. 11-16
Author(s):  
O. Pushkar'ov ◽  
A. Zubko ◽  
I. Sevruk ◽  
V. Dolin
Keyword(s):  
Hydrogen Bonds ◽  
Proton Conductivity ◽  
Tritiated Water ◽  
High Mobility ◽  
Hydrogen Isotopes ◽  
Water Molecules ◽  
Proton Conducting ◽  
Partial Dissociation ◽  
Surface Modified ◽  
Conducting Membranes

Based on the analysis of the features of electroosmotic processes that are implemented in proton-conducting membranes, the possibility of fractioning hydrogen isotopes in electrolytes formed using tritiated water (HTO) is estimated. The interaction of the solution with the membranes in their channels leads to polarization and partial dissociation of the electrolyte molecules. In water molecules, when protium is replaced by a heavy isotope of hydrogen, the energy of breaking of hydrogen bonds increases and the process of their dissociation proceeds predominantly according to the scheme: HTO ↔ H+ + TO—. A part of the released protons can join water molecules to form the H3O+ ion. H3O+ and TO— ions are more mobile than other singly charged ions. The main characteristic that determines the suitability of electroosmotic membranes to the fractionation of hydrogen isotopes is proton conductivity. The released protons have anomalously high mobility due to their small size, tunnel and relay movement through hydrogen bonds between adjacent polar groups in the channels of the proton-conducting membranes. To ensure high proton conductivity in the pores and channels of the membranes, modifying substances are fixed, which contain the groups: –ОН- , –NH2, –NH, –SH, –COOH, –SO3H, acid salts and oxides, containing surface proton-conducting groups. To create proton-conducting membranes, it is possible to use surface-modified β-alumina (β-Al2O3(H3O+)) and protonated (H3O+) montmorillonite with ionic conductivity (5х103 – 4х104 Ohm х cm–1). The most effective are surface modifiers with negatively charged sulfonic groups. The imposition of an external electric field leads to the movement of ions in the electrolyte, which leads to a redistribution of the isotope ratio in the near-anode and cathode spaces.

scholarly journals Synthesis and crystal structure of a 6-chloronicotinate salt of a one-dimensional cationic nickel(II) coordination polymer with 4,4′-bipyridine

2020 ◽  
Vol 76 (5) ◽  
pp. 599-604
Author(s):  
Nives Politeo ◽  
Mateja Pisačić ◽  
Marijana Đaković ◽  
Vesna Sokol ◽  
Boris-Marko Kukovec
Keyword(s):  
Molecular Structure ◽  
Coordination Polymer ◽  
Three Dimensional ◽  
Polymeric Chain ◽  
Water Molecules ◽  
Sulfate Heptahydrate ◽  
Synthesis And Crystal Structure ◽  
One Dimensional ◽  
Polymeric Chains ◽  
Hydrogen Bonded

A 6-chloronicotinate (6-Clnic) salt of a one-dimensional cationic nickel(II) coordination polymer with 4,4′-bipyridine (4,4′-bpy), namely, catena-poly[[[tetraaquanickel(II)]-μ-4,4′-bipyridine-κ2 N:N′] bis(6-chloronicotinate) tetrahydrate], {[Ni(C10H8N2)(H2O)4](C6H3ClNO2)2·4H2O} n or {[Ni(4,4′-bpy)(H2O)4](6-Clnic)2·4H2O} n , (1), was prepared by the reaction of nickel(II) sulfate heptahydrate, 6-chloronicotinic acid and 4,4′-bipyridine in a mixture of water and ethanol. The molecular structure of 1 comprises a one-dimensional polymeric {[Ni(4,4′-bpy)(H2O)4]2+} n cation, two 6-chloronicotinate anions and four water molecules of crystallization per repeating polymeric unit. The nickel(II) ion in the polymeric cation is octahedrally coordinated by four water molecule O atoms and by two 4,4′-bipyridine N atoms in the trans position. The 4,4′-bipyridine ligands act as bridges and, thus, connect the symmetry-related nickel(II) ions into an infinite one-dimensional polymeric chain extending along the b-axis direction. In the extended structure of 1, the polymeric chains of {[Ni(4,4′-bpy)(H2O)4]2+} n , the 6-chloronicotinate anions and the water molecules of crystallization are assembled into an infinite three-dimensional hydrogen-bonded network via strong O—H...O and O—H...N hydrogen bonds, leading to the formation of the representative hydrogen-bonded ring motifs: tetrameric R 2 4(8) and R 4 4(10) loops, a dimeric R 2 2(8) loop and a pentameric R 4 5(16) loop.

scholarly journals Diosgenin hemihydrate

2012 ◽  
Vol 68 (8) ◽  
pp. o2357-o2357 ◽  
Author(s):  
María-Guadalupe Hernández Linares ◽  
Sylvain Bernès ◽  
Marcos Flores-Alamo ◽  
Gabriel Guerrero-Luna ◽  
Anselmo A. Martínez-Gallegos
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Dimethyl Sulfoxide ◽  
Starting Material ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
X Ray ◽  
Hydroxy Groups ◽  
Hydrogen Bonded

Diosgenin [or (22R,25R)-spirost-5-en-3β-ol] is the starting material of the Marker degradation, a cheap semi-synthesis of progesterone, which has been designated as an International Historic Chemical Landmark. Thus far, a single X-ray structure for diosgenin is known, namely its dimethyl sulfoxide solvate [Zhanget al.(2005).Acta Cryst.E61, o2324–o2325]. We have now determined the structure of the hemihydrate, C27H42O3·0.5H2O. The asymmetric unit contains two diosgenin molecules, with quite similar conformations, and one water molecule. Hydroxy groups in steroids and water molecules form O—H...O hydrogen-bondedR54(10) ring motifs. Fused edge-sharingR(10) rings form a backbone oriented along [100], which aggregates the diosgenin molecules in the crystal structure.

Sign in / Sign up

Export Citation Format

Share Document