Polarizable acid–water hydrogen bonds with aqueous solutions of carboxylic acids

1980 ◽  
Vol 76 (0) ◽  
pp. 14-25 ◽  
Author(s):  
Martin Leuchs ◽  
Georg Zundel
Keyword(s):  
Hydrogen Bonds ◽  
Aqueous Solutions ◽  
Carboxylic Acids ◽  
Acid Water ◽  
Water Hydrogen

Formation of acid–water hydrogen bonds with large proton polarizability and molecular processes with dissociation of acids in the pKa range 0–4

1982 ◽  
Vol 60 (16) ◽  
pp. 2118-2131 ◽  
Author(s):  
Martin Leuchs ◽  
Georg Zundel
Keyword(s):  
Hydrogen Bonds ◽  
Acid Water ◽  
Wave Number ◽  
Molecular Processes ◽  
Number Range ◽  
Degree Of Dissociation ◽  
Proton Potential ◽  
Entropy Effects ◽  
Water Hydrogen ◽  
The Continuum

Aqueous solutions of fourteen acids in the pKa region 0–4 were studied by ir spectroscopy as a function of concentration. All data are summarized in a table. The degree of dissociation was determined from bands of the anions. The removal of the protons from the anions decreases in the following series of the acids CF3COOH, H2CrO4, (HIO3), CF2HCOOH, HPO(OH)2, HSO4−, (HSeO4−), H2POOH, PO(OH)3, AsO(OH)3 (Table 1, columns 3 and 4). Continua indicate the formation of hydrogen bonds with large proton polarizabilities. In the case of H3PO3, H3PO4, and H3AsO4, the acid–acid hydrogen bonds are still polarizable although they have relatively asymmetrical proton potentials. The acid–water hydrogen bonds (I) [Formula: see text] (II) may show considerable proton polarizability, as indicated by strong continuous absorptions. The proton potential, and thus the proton polarizability of the acid–water hydrogen bonds, are discussed taking into consideration the intensity and the wave number range of the continuum (column 7), as well as the line width of the vibration with δ OH character (column 9). With increasing asymmetry of the hydrogen bonds, the continuum changes to the bands observed with asymmetrical hydrogen bonds. The sequence of acids in the series arranged according to the degree of dissociation is not the same as the sequence according to the intensity of the continuum and proton polarizability. This is explained by the fact that the proton polarizability is mainly determined by the shape of the proton potential, whereas the dissociation equilibrium is also influenced by entropy effects associated with hydrate structure formation.It is shown that the following molecular processes are of significance for the dissociation of the acids: the formation of acid–water hydrogen bonds with proton polarizability, whereby the weight of the polar proton-limiting structure [Formula: see text] increases with increasing addition of water molecules. Besides the shape of the proton potential, the entropy effects mentioned influence the degree of dissociation, too. Finally, the positive charge transfers from the acid–water into water–water hydrogen bonds, i.e., H5O2+ is formed.

Polarizable acid–acid and acid–water hydrogen bonds with H3PO2, H3PO3, H3PO4, and H3AsO4

1979 ◽  
Vol 57 (5) ◽  
pp. 487-493 ◽  
Author(s):  
Martin Leuchs ◽  
Georg Zundel
Keyword(s):  
Hydrogen Bonds ◽  
Acid Water ◽  
Boundary Structure ◽  
Water Proton ◽  
Pure Liquid ◽  
Strongly Correlated ◽  
Hypophosphorous Acid ◽  
Acid Acid ◽  
Energy Surfaces ◽  
Water Hydrogen

Hypophosphorous, phosphorous, phosphoric, and arsenic acids, pure and their aqueous solutions were studied by ir spectroscopy. Strong continuous absorptions observed with the pure liquid acids and with solutions containing less than one water molecule per acid molecule demonstrate that acid–acid hydrogen bonds in these systems are easily polarizable. The discussion of the PO and AsO bands as well as the discussion of the structure of the continuum demonstrates, however, that the degree of asymmetry of the energy surfaces in these hydrogen bonds is relatively large. It is shown that extended networks of such bonds exist. Due to the polarizability of these bonds, the proton motion in these bonds is strongly correlated. With addition of water, easily polarizable acid–water hydrogen bonds (I) [Formula: see text] (II) are formed. The energy surfaces in these hydrogen bonds are similar to those in the acid–acid hydrogen bonds. With further addition of water, proton boundary structure II receives noticeable weight, i.e., the degree of asymmetry of the energy surfaces in these bonds decreases due to addition of water molecules. The degree of symmetry of the energy surfaces in the acid–water hydrogen bonds increases in the series arsenic, phosphoric, phosphorous, and hypophosphorous acid.

Computer simulation of structure and mobility of water hydrogen bonds net in aqueous solutions of some chemical compounds

2005 ◽  
Author(s):  
Pavel E. Kuznetsov ◽  
Svetlana M. Rogacheva ◽  
Era B. Popyhova ◽  
Zoya A. Simonova ◽  
Timophey E. Pylaev
Keyword(s):  
Computer Simulation ◽  
Hydrogen Bonds ◽  
Aqueous Solutions ◽  
Chemical Compounds ◽  
Water Hydrogen

Adducts of meso and racemic 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane with trigonally trisubstituted benzene carboxylic acids: supramolecular structures in one and two dimensions

2000 ◽  
Vol 56 (6) ◽  
pp. 1054-1062 ◽  
Author(s):  
Colin J. Burchell ◽  
George Ferguson ◽  
Alan J. Lough ◽  
Christopher Glidewell
Keyword(s):  
Hydrogen Bonds ◽  
Carboxylic Acids ◽  
Supramolecular Structure ◽  
Two Dimensions ◽  
Supramolecular Structures ◽  
Acid Water ◽  
Water Molecules ◽  
One Dimensional ◽  
Space Groups

The meso and racemic forms of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, C16H36N4 (tet-a and tet-b, respectively), form adducts with trigonally trisubstituted benzene carboxylic acids; tet-a–3,5-dinitrobenzoic acid (1/2) (1), tet-a–5-hydroxyisophthalic acid–water (1/1/1) (3) and tet-b–5-hydroxyisophthalic acid–water (1/1/1) (4) are all salts, [C16H38N4]2+·2[C7H3N2O6]− (1) and [C16H38N4]2+·[C8H4O5]2−·H2O (3) and (4). The conformations of the [(tet-a)H2]2+ and [(tet-b)H2]2+ cations are entirely different: [(tet-a)H2]2+ is precisely centrosymmetric in (1) and approximately so in (3), while [(tet-b)H2]2+ has approximate C 2 symmetry in (4). In each salt the cation forms two intramolecular N—H...N and four intermolecular N—H...O hydrogen bonds. In (1) the supramolecular structure is one-dimensional, a C 2 2(13)[R 2 4(16)] chain of rings. Compounds (3) and (4) crystallize in space groups P212121 and P21/c, respectively, but the supramolecular structures are very similar: in each, the anions and the water molecules form a C(7)[R 3 3(13)] chain of rings, generated in (3) by a 21 axis and in (4) by a glide plane. These chains are linked, in both (3) and (4), by cations to form sheets. Adjacent meso cations in (3) are related by a 21 axis and adjacent chiral cations in (4) are related by a glide plane.

Carboxylic acids in aqueous solutions: Hydrogen bonds, hydrophobic effects, concentration fluctuations, ionization, and catalysis

2018 ◽  
Vol 149 (24) ◽  
pp. 244503 ◽  
Author(s):  
Torsten Gailus ◽  
Holger Krah ◽  
Volker Kühnel ◽  
Andreas Rupprecht ◽  
Udo Kaatze
Keyword(s):  
Hydrogen Bonds ◽  
Aqueous Solutions ◽  
Carboxylic Acids ◽  
Concentration Fluctuations ◽  
Hydrophobic Effects

Ab initio QM/MM dynamics of anion–water hydrogen bonds in aqueous solution

2005 ◽  
Vol 403 (4-6) ◽  
pp. 314-319 ◽  
Author(s):  
Anan Tongraar ◽  
Bernd Michael Rode
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Ab Initio ◽  
Water Hydrogen
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