An infrared study of water–ion interactions in perfluorosulfonate (Nafion) membranes

1984 ◽  
Vol 62 (5) ◽  
pp. 958-966 ◽  
Author(s):  
Sylvio Quezado ◽  
Jan C. T. Kwak ◽  
Michael Falk
Keyword(s):  
Ion Pairs ◽  
Acid Strength ◽  
Lewis Base ◽  
Water Molecules ◽  
Infrared Study ◽  
Nafion Membranes ◽  
Base Strength ◽  
Mode Of Attachment ◽  
Water Contents ◽  
Hydrogen Bonded

We have studied the infrared spectra of Nafion membranes in twenty different cationic forms, in order to characterize the water–anion–cation interactions at low water contents. Spectra in the OH stretching region and in the H—O—H bending region allow the distinction between hydrogen-bonded and non-hydrogen-bonded water molecules, and yield information on the mode of attachment of water molecules to the anion–cation pairs. When there is a good match between the Lewis acid strength of the cation and the Lewis base strength of the anion, ion pairs are relatively stable and water molecules tend to attach on the outside. When the acid strength of the cation and the base strength of the anion are mismatched, as is the case for small cations of high charge or for large cations of low charge, water molecules tend to be inserted between the ion pairs even at the lowest water contents.

An infrared study of water in perfluorosulfonate (Nafion) membranes

1980 ◽  
Vol 58 (14) ◽  
pp. 1495-1501 ◽  
Author(s):  
Michael Falk
Keyword(s):  
Water Molecules ◽  
Salt Solutions ◽  
Absorption Bands ◽  
Infrared Study ◽  
Oh Groups ◽  
Ion Clusters ◽  
Aqueous Salt Solutions ◽  
Nafion Membranes ◽  
Phase Water ◽  
Sodium Form

We have studied the infrared spectra of H2O, D2O, and HDO in hydrated Nafion membranes in the sodium form. The spectrum of isotopically isolated HDO exhibits two distinct absorption bands in the OH stretching region and similarly in the OD stretching region. These bands have been taken to correspond to two distinct environments of the OH groups in Nafion, identified as [Formula: see text] and[Formula: see text]. It appears that a substantial proportion of water molecules have an OH group (or occasionally both OH groups) exposed to the fluorocarbon environment. This implies that the hydrated ion clusters are either much smaller than previously estimated or, more likely, are non-spherical in shape with frequent local intrusions of the fluorocarbon phase. Water in Nafion is much less strongly hydrogen-bonded than water in aqueous salt solutions at the same temperature and may be expected to have distinct physical properties.

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.

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.

Empirical Lewis acid strengths for 135 cations bonded to oxygen

2017 ◽  
Vol 73 (5) ◽  
pp. 956-961 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Lewis Acid ◽  
Strong Correlation ◽  
Ionization Energy ◽  
Acid Strength ◽  
Lewis Base

New and updated Lewis acid strengths are listed for 135 cations bonded to oxygen for use with published Lewis base strengths. A strong correlation between Lewis acid strength and ionization energy is shown, and correlation with electronegativity is confirmed.

scholarly journals 2-Amino-4-methylpyridinium 4-methoxybenzoate dihydrate

IUCrData ◽  
2017 ◽  
Vol 2 (5) ◽  
Author(s):  
P. Sivakumar ◽  
G. Ezhamani ◽  
S. Israel ◽  
G. Chakkaravarthi
Keyword(s):  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Ion Pairs ◽  
Three Dimensional ◽  
Water Molecules ◽  
Π Stacking ◽  
Dimensional Network ◽  
Centroid Distance ◽  
Molecular Salt

In the title hydrated molecular salt, C6H9N2+·C8H7O3−·2H2O, the cation is protonated at the pyridine N atom. The cation and anion are linked by a pair of N—H...O hydrogen bonds, which generates anR22(8) loop, and the dihedral angle between their ring planes is 16.07 (14)°. The ion pairs are linked by O—H...O hydrogen bonds involving the water molecules, generating a three-dimensional network. Weak C—H...O and aromatic π–π stacking [centroid-to-centroid distance = 3.5874 (17) Å] interactions are also observed.

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.

2,2′-[m-Phenylenebis(methyleneimino)]dipyridinium dichloridobis(4-formylbenzoato-κ2 O,O′)cadmate(II) dihydrate

2007 ◽  
Vol 63 (11) ◽  
pp. m2834-m2834
Author(s):  
Zhao-Peng Deng ◽  
Shan Gao ◽  
Li-Hua Huo ◽  
Hui Zhao
Keyword(s):  
Rotation Axis ◽  
Chain Structure ◽  
Octahedral Geometry ◽  
Water Molecules ◽  
Carboxylate Group ◽  
Cl Atoms ◽  
Hydrogen Bonded

The CdII atom in the title salt, (C18H20N4)[CdCl2(C8H5O3)2]·2H2O, lies on a twofold rotation axis. It is chelated by the carboxylate group and exists in an octahedral geometry, with the Cl atoms cis to each other. The dication also lies on a twofold rotation axis. The cation and anion interact through one of the uncoordinated water molecules, forming a hydrogen-bonded chain structure that runs along the a axis.

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