Why do water molecules around small hydrophobic solutes form stronger hydrogen bonds than in the bulk?

2020 ◽  
Vol 1864 (4) ◽  
pp. 129537 ◽  
Author(s):  
Franci Merzel ◽  
Franc Avbelj
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecules ◽  
Hydrophobic Solutes ◽  
Small Hydrophobic

scholarly journals Origin of hydrophobicity and enhanced water hydrogen bond strength near purely hydrophobic solutes

2016 ◽  
Vol 114 (2) ◽  
pp. 322-327 ◽  
Author(s):  
Joze Grdadolnik ◽  
Franci Merzel ◽  
Franc Avbelj
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Hydrophobic Hydration ◽  
Bulk Water ◽  
Water Molecules ◽  
Classical View ◽  
Fundamental Level ◽  
Hydrophobic Solute ◽  
Hydrophobic Solutes ◽  
Water Hydrogen

Hydrophobicity plays an important role in numerous physicochemical processes from the process of dissolution in water to protein folding, but its origin at the fundamental level is still unclear. The classical view of hydrophobic hydration is that, in the presence of a hydrophobic solute, water forms transient microscopic “icebergs” arising from strengthened water hydrogen bonding, but there is no experimental evidence for enhanced hydrogen bonding and/or icebergs in such solutions. Here, we have used the redshifts and line shapes of the isotopically decoupled IR oxygen–deuterium (O-D) stretching mode of HDO water near small purely hydrophobic solutes (methane, ethane, krypton, and xenon) to study hydrophobicity at the most fundamental level. We present unequivocal and model-free experimental proof for the presence of strengthened water hydrogen bonds near four hydrophobic solutes, matching those in ice and clathrates. The water molecules involved in the enhanced hydrogen bonds display extensive structural ordering resembling that in clathrates. The number of ice-like hydrogen bonds is 10–15 per methane molecule. Ab initio molecular dynamics simulations have confirmed that water molecules in the vicinity of methane form stronger, more numerous, and more tetrahedrally oriented hydrogen bonds than those in bulk water and that their mobility is restricted. We show the absence of intercalating water molecules that cause the electrostatic screening (shielding) of hydrogen bonds in bulk water as the critical element for the enhanced hydrogen bonding around a hydrophobic solute. Our results confirm the classical view of hydrophobic hydration.

scholarly journals Hydration of Biological Macromolecules: From Small Solutes to Proteins and Nucleic Acids

1996 ◽  
Vol 463 ◽  
Author(s):  
Shekhar Garde ◽  
Gerhard Hummer ◽  
Michael E. Paulaitis ◽  
Angel E. Garcia
Keyword(s):  
Potential Of Mean Force ◽  
Water Molecules ◽  
Biological Macromolecules ◽  
Particle Correlation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Catabolite Activator Protein ◽  
Hydrophobic Solutes ◽  
Small Hydrophobic ◽  
Good Agreement

We present a method that uses two- and three-particle correlation functions between solute atoms and water molecules to approximate the density profile of water surrounding biomolecules. The method is based on a potential of mean force expansion and uses X-ray crystallography, NMR, or modeling structural input information on the biomolecule. For small hydrophobic solutes, we have calculated entropies of hydration using the predicted water densities that are in good agreement with experimental results. We have also predicted the hydration of thecatabolite activator protein-DNAcomplex. The method is extremely efficient and makes possible the study of hydration of large biomolecules within CPU minutes.

The effect of partial methylation of the glycine amino group on crystal structure inN,N-dimethylglycine and its hemihydrate

2012 ◽  
Vol 68 (8) ◽  
pp. o283-o287 ◽  
Author(s):  
Vasily S. Minkov ◽  
Elena V. Boldyreva
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Water Molecules ◽  
Amino Group ◽  
Asymmetric Unit ◽  
Partial Methylation ◽  
Space Groups ◽  
Carboxylate Groups ◽  
Anhydrous Compound ◽  
Additional Hydrogen

N,N-Dimethylglycine, C4H9NO2, and its hemihydrate, C4H9NO2·0.5H2O, are discussed in order to follow the effect of the methylation of the glycine amino group (and thus its ability to form several hydrogen bonds) on crystal structure, in particular on the possibility of the formation of hydrogen-bonded `head-to-tail' chains, which are typical for the crystal structures of amino acids and essential for considering amino acid crystals as mimics of peptide chains. Both compounds crystallize in centrosymmetric space groups (PbcaandC2/c, respectively) and have twoN,N-dimethylglycine zwitterions in the asymmetric unit. In the anhydrous compound, there are no head-to-tail chains but the zwitterions formR44(20) ring motifs, which are not bonded to each other by any hydrogen bonds. In contrast, in the crystal structure ofN,N-dimethylglycinium hemihydrate, the zwitterions are linked to each other by N—H...O hydrogen bonds into infiniteC22(10) head-to-tail chains, while the water molecules outside the chains provide additional hydrogen bonds to the carboxylate groups.

scholarly journals Effect of permanent magnetic field on scale inhibition property of circulating water

2017 ◽  
Vol 76 (8) ◽  
pp. 1981-1991 ◽  
Author(s):  
Lili Jiang ◽  
Xiayan Yao ◽  
Haitao Yu ◽  
Xingang Hou ◽  
Zongshu Zou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hydrogen Bonds ◽  
Flow Velocity ◽  
Magnetic Field Intensity ◽  
Water Molecules ◽  
Relative Variation ◽  
Initial Concentration ◽  
Circulating Water ◽  
Scale Inhibition ◽  
Inhibition Property

Effect of a permanent magnet field on the scale inhibition property of circulating water was investigated. Orthogonal experiments of L16(45) were performed and analyzed using the range analysis method. The operating parameters included magnetic field intensity, initial concentration of Ca2+ and Mg2+, magnetic treatment time, temperature, and flow velocity. Scale inhibition rate, hardness, relative variation in the proportion of free water molecules, electrical conductivity, and relative variation of molecular energy were chosen as the objectives. In addition, the morphology and the composition of CaCO3 and MgCO3 scale were studied by X-ray diffraction analysis. The optimal conditions were initial concentration of 900 mg/L, magnetic field intensity of 0.5 T, temperature of 303 K, time of 54 h and flow velocity of 0.17 m/s. The nuclear magnetic resonance results demonstrated that the number of hydrogen bonds increased between water molecules and hydrated ions. The magnetic field can promote the increase in the number of hydrogen bonds, which can inhibit the formation of calcium and magnesium carbonate precipitation. Moreover, the ratio of calcite, aragonite and vaterite will be changed at different magnetic field intensities, and the aragonite ratio will reach the peak at the optimum conditions.

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.

scholarly journals Piperazinium hydrogenarsenate monohydrate

2007 ◽  
Vol 63 (3) ◽  
pp. m905-m907 ◽  
Author(s):  
Hazel S. Wilkinson ◽  
William T. A. Harrison
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecule ◽  
Title Compound ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Compound C

In the title compound, C4H12N2 2+·HAsO4 2−·H2O, the component species interact by way of N—H...O and O—H...O hydrogen bonds, the latter leading to infinite sheets of HAsO4 2− anions and water molecules containing R 6 6(18) loops. The asymmetric unit contains one anion, one water molecule and half each of two centrosymmetric cations.

scholarly journals Crystal structures of {[Cu(Lpn)2][Fe(CN)5(NO)]·H2O}nand {[Cu(Lpn)2]3[Cr(CN)6]2·5H2O}n[where Lpn = (R)-propane-1,2-diamine]: two heterometallic chiral cyanide-bridged coordination polymers

2015 ◽  
Vol 71 (4) ◽  
pp. 392-397
Author(s):  
Olha Sereda ◽  
Helen Stoeckli-Evans
Keyword(s):  
Hydrogen Bonds ◽  
Coordination Polymers ◽  
Three Dimensional ◽  
Water Molecules ◽  
Two Dimensional ◽  
Asymmetric Unit ◽  
Compound I ◽  
Distorted Octahedral ◽  
Coordination Spheres ◽  
Compound Ii

The title compounds,catena-poly[[[bis[(R)-propane-1,2-diamine-κ2N,N′]copper(II)]-μ-cyanido-κ2N:C-[tris(cyanido-κC)(nitroso-κN)iron(III)]-μ-cyanido-κ2C:N] monohydrate], {[Cu(Lpn)2][Fe(CN)5(NO)]·H2O}n, (I), and poly[[hexa-μ-cyanido-κ12C:N-hexacyanido-κ6C-hexakis[(R)-propane-1,2-diamine-κ2N,N′]dichromium(III)tricopper(II)] pentahydrate], {[Cu(Lpn)2]3[Cr(CN)6]2·5H2O}n, (II) [where Lpn = (R)-propane-1,2-diamine, C3H10N2], are new chiral cyanide-bridged bimetallic coordination polymers. The asymmetric unit of compound (I) is composed of two independent cation–anion units of {[Cu(Lpn)2][Fe(CN)5)(NO)]} and two water molecules. The FeIIIatoms have distorted octahedral geometries, while the CuIIatoms can be considered to be pentacoordinate. In the crystal, however, the units align to form zigzag cyanide-bridged chains propagating along [101]. Hence, the CuIIatoms have distorted octahedral coordination spheres with extremely long semicoordination Cu—N(cyanido) bridging bonds. The chains are linked by O—H...N and N—H...N hydrogen bonds, forming two-dimensional networks parallel to (010), and the networks are linkedviaN—H...O and N—H...N hydrogen bonds, forming a three-dimensional framework. Compound (II) is a two-dimensional cyanide-bridged coordination polymer. The asymmetric unit is composed of two chiral {[Cu(Lpn)2][Cr(CN)6]}−anions bridged by a chiral [Cu(Lpn)2]2+cation and five water molecules of crystallization. Both the CrIIIatoms and the central CuIIatom have distorted octahedral geometries. The coordination spheres of the outer CuIIatoms of the asymmetric unit can be considered to be pentacoordinate. In the crystal, these units are bridged by long semicoordination Cu—N(cyanide) bridging bonds forming a two-dimensional network, hence these CuIIatoms now have distorted octahedral geometries. The networks, which lie parallel to (10-1), are linkedviaO—H...O, O—H...N, N—H...O and N—H...N hydrogen bonds involving all five non-coordinating water molecules, the cyanide N atoms and the NH2groups of the Lpn ligands, forming a three-dimensional framework.

scholarly journals Crystal structure of the new hybrid material bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate

2015 ◽  
Vol 71 (11) ◽  
pp. 1384-1387
Author(s):  
Marwen Chouri ◽  
Habib Boughzala
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Molar Ratio ◽  
Water Molecules ◽  
Site Symmetry ◽  
Two Dimensional ◽  
Slow Evaporation ◽  
Solution Ph

The title compound bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was obtained by slow evaporation at room temperature of a hydrochloric aqueous solution (pH = 1) containing bismuth(III) nitrate and 1,4-diazabicyclo[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10]4−bioctahedra (site symmetry -1) separated by layers of organic 1,4-diazoniabicyclo[2.2.2]octane dications [(DABCOH2)2+] and water molecules. O—H...Cl, N—H...O and N—H...Cl hydrogen bonds lead to additional cohesion of the structure.

Hydrate von Li3VO4: Synthese und Strukturchemie / Hydrates of Li3VO4: Synthesis and Structural Chemistry

2007 ◽  
Vol 62 (10) ◽  
pp. 1235-1245 ◽  
Author(s):  
Simone Schnabel ◽  
Caroline Röhr
Keyword(s):  
Hydrogen Bonds ◽  
Building Blocks ◽  
Water Molecules ◽  
Space Group ◽  
Space Groups ◽  
Monoclinic Form ◽  
Lithium Sulfide ◽  
3D Network ◽  
Coordination Spheres ◽  
A Chain

Stoichiometric hydrates of Li3VO4, the hexahydrate and two polymorphs of the octahydrate, were prepared by evaporation of alkaline aqueous solutions 1 molar in LiOH and 0.5 molar in the metavanadate LiVO3 at r. t. with or without the addition of Lithium sulfide, i. e. at different pH values. Their crystal structures have been determined and refined using single crystal X-ray data; all lithium and hydrogen atom positions were localised and refined without contraints. All three title compounds crystallise in non-centrosymmetric space groups. The water molecules belong to the tetrahedral coordination spheres of the Li cations, i. e. they are embedded as water of coordination exclusively. The tetrahedral orthovanadate(V) anions VO3−4 and the LiO4 tetrahedra are connected via common O corners to form building units which are further held together by strong, nearly linear hydrogen bonds. The hexahydrate Li3VO4 ・ 6H2O (space group R3, a = 962.9(2), c = 869.2(2) pm, Z = 3, R1 = 0.0260) contains isolated orthovanadate(V) anions VO3−4 surrounded by a 3D network of cornersharing Li(H2O)4 tetrahedra forming rings of three, seven and eight units. The water molecules are ‘isolated’ in the sense that no hydrogen bonds are formed between water molecules. The octahydrate is dimorphous: The triclinic polymorph of Li3VO4 ・ 8H2O (space group P1, a = 592.6(2), b = 651.3(2), c = 730.2(4) pm, α = 89.09(2), β = 89.43(2), γ = 88.968(12)°, Z = 1, R1 = 0.0325) contains two types of chains of tetrahedra: One consists of corner-sharing Li(H2O)4 tetrahedra only, the second one is formed by alternating LiO4 and VO4 tetrahedra, also sharing oxygen corners. Only one water molecule is ‘isolated’, the other seven form a branched fragment of a chain with hydrogen bonds between them. In the monoclinic form of Li3VO4・8H2O (space group Pc, a = 732.6(1), b = 653.7(1), c = 1292.9(3) pm, β = 112.21(1)°, Z = 2, R1 = 0.0289) a fragment of a chain of three LiO4 tetrahedra, two of which share a common edge, and one VO4 tetrahedron represent the formular unit. These building blocks are connected via hydrogen bonds formed by three ‘isolated’ water molecules and a chain fragment of five connected water molecules.

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