scholarly journals Water inside β-cyclodextrin cavity: amount, stability and mechanism of binding

2019 ◽  
Vol 15 ◽  
pp. 1592-1600 ◽  
Author(s):  
Stiliyana Pereva ◽  
Valya Nikolova ◽  
Silvia Angelova ◽  
Tony Spassov ◽  
Todor Dudev
Keyword(s):  
Inclusion Complexes ◽  
Water Clusters ◽  
Bound Water ◽  
Thermodynamic Characteristics ◽  
Water Molecules ◽  
Native State ◽  
Hydrophobic Substances ◽  
Cyclodextrin Cavity ◽  
Stabilizing Factors ◽  
Native Host

Cyclodextrins (CDs) are native host systems with inherent ability to form inclusion complexes with various molecular entities, mostly hydrophobic substances. Host cyclodextrins are accommodative to water molecules as well and contain water in the native state. For β-cyclodextrin (β-CD), there is no consensus regarding the number of bound water molecules and the location of their coordination. A number of intriguing questions remain: (1) Which localities of the host’s macrocycle are the strongest attractors for the guest water molecules? (2) What are the stabilizing factors for the water clusters in the interior of β-CD and what type of interactions between water molecules and cavity walls or between the water molecules themselves are dominating the energetics of the β-CD hydration? (3) What is the maximum number of water molecules inside the cavity of β-CD? (4) How do the thermodynamic characteristics of β-CD hydration compare with those of its smaller α-cyclodextrin (α-CD) counterpart? In this study, we address these questions by employing a combination of experimental (DSC/TG) and theoretical (DFT) approaches.

scholarly journals SANS quantification of bound water in water-soluble polymers across multiple concentration regimes

Soft Matter ◽  
2021 ◽  
Author(s):  
Helen Yao ◽  
Bradley D. Olsen
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Bound Water ◽  
Water Soluble ◽  
Wide Concentration Range ◽  
Water Molecules ◽  
Water Soluble Polymers ◽  
Soluble Polymers

Small-angle neutron scattering is used to measure the number of bound water molecules associating with three polymers over a wide concentration range. Different fitting workflows are evaluated and recommended depending on the concentration regime.

Substrate specificity and affinity of a protein modulated by bound water molecules

Nature ◽  
1989 ◽  
Vol 340 (6232) ◽  
pp. 404-407 ◽  
Author(s):  
F. A. Quiocho ◽  
D. K. Wilson ◽  
N. K. Vyas
Keyword(s):  
Substrate Specificity ◽  
Bound Water ◽  
Water Molecules

scholarly journals Structure and hydrogen bonding of the hydrated selenite and selenate ions in aqueous solution

2014 ◽  
Vol 43 (17) ◽  
pp. 6315-6321 ◽  
Author(s):  
Lars Eklund ◽  
Ingmar Persson
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonding ◽  
Free Electron ◽  
Electron Pair ◽  
Bound Water ◽  
Water Molecules ◽  
Hydration Sphere ◽  
Free Electron Pair

The selenite ion has an asymmetric hydration sphere with loosely electrostatically bound water molecules outside the free electron pair.

Extrem asymmetrisch gebundene Wassermoleküle-Kristallstrukturen von Sr(OH)Cl · 4 H2O, Sr(OH)Br · 4 H2O und Ba(OH)I·4 H2O / Extremely Asymmetrically Bound Water Molecules-Crystal Structures of Sr(OH)Cl · 4 H2O, Sr(OH)Br · 4 H2O, and Ba(OH)I·4 H2O

1991 ◽  
Vol 46 (10) ◽  
pp. 1279-1286 ◽  
Author(s):  
Thomas Kellersohn ◽  
Konrad Beckenkamp ◽  
Heinz Dieter Lutz
Keyword(s):  
Crystal Structures ◽  
Bound Water ◽  
Structure Type ◽  
Water Molecules ◽  
Halide Ions ◽  
Weak Hydrogen Bond ◽  
Scanning Calorimetry ◽  
Unknown Structure ◽  
Stretching Vibrations ◽  
Strong Distortion

The crystal structures of isotypic Sr(OH)Cl ·4 H2O, Sr(OH)Br·4 H2O, and Ba(OH)I·4 H2O are reported. The title compounds crystallize in a hitherto unknown structure type, space group PĪ, Z = 2. The final R values obtained are 0.0261, 0.069, and 0.062, respectively. The coordination of the metal ions is monocapped square antiprismatic with 7 H2O, 1 OH- and 1 halide ion. The halide ions separate metal/water/hydroxide layers. Each of the four crystallographically different water molecules serves as donor for one very strong and one very weak hydrogen bond and, hence, is extremely asymmetrically bound. Owing to this strong distortion, the largest one known so far, the OH stretching vibrations of the H2O molecules are intramolecularly decoupled as shown from vibrational spectra. The enthalpies of dehydration obtained from differential scanning calorimetry are reported.

scholarly journals Self-Organization of Water Molecules Over 11-Year Solar Cycle

2021 ◽  
Author(s):  
Igor Shevchenko
Keyword(s):  
Solar Activity ◽  
Water Clusters ◽  
The Self ◽  
Self Organization ◽  
Water Molecules ◽  
Annual Variations ◽  
The Earth ◽  
Rate Of Hydrolysis ◽  
Rotation Of The Earth ◽  
Northern And Southern Hemispheres

Abstract The variations of solar activity and distribution of solar energy due to the rotation of the Earth around its axis and around the Sun exert a strong influence on the self-organization of water molecules. As a result, the rate of hydrolytic processes with the participation of water clusters displays diurnal, very large annual variations, and is also modulated by the 11-year cycles of solar activity. It also depends on the geographic latitude and can be different at the same time in the Northern and Southern Hemispheres. This phenomenon is well accounted for by the influence of muons on the self-organization of water molecules. Muons are constantly generated in the upper atmosphere by the solar wind. They reach the surface of the Earth and can penetrate to some depth underground. Buildings also absorb muons. For this reason, the rate of hydrolysis outside and inside buildings, as well as underground, can differ significantly from each other.

scholarly journals Crystal structures of four dimeric manganese(II) bromide coordination complexes with various derivatives of pyridine N-oxide

2019 ◽  
Vol 75 (8) ◽  
pp. 1284-1290
Author(s):  
Sheridan Lynch ◽  
Genevieve Lynch ◽  
Will E. Lynch ◽  
Clifford W. Padgett
Keyword(s):  
Hydrogen Bonding ◽  
Solvent Molecule ◽  
Bound Water ◽  
Manganese Atom ◽  
Coordination Complexes ◽  
Water Molecules ◽  
Inversion Center ◽  
Dimeric Complex ◽  
Bromide Ions ◽  
Derivatives Of

Four manganese(II) bromide coordination complexes have been prepared with four pyridine N-oxides, viz. pyridine N-oxide (PNO), 2-methylpyridine N-oxide (2MePNO), 3-methylpyridine N-oxide (3MePNO), and 4-methylpyridine N-oxide (4MePNO). The compounds are bis(μ-pyridine N-oxide)bis[aquadibromido(pyridine N-oxide)manganese(II)], [Mn2Br4(C5H5NO)4(H2O)2] (I), bis(μ-2-methylpyridine N-oxide)bis[diaquadibromidomanganese(II)]–2-methylpyridine N-oxide (1/2), [Mn2Br4(C6H7NO)2(H2O)4]·2C6H7NO (II), bis(μ-3-methylpyridine N-oxide)bis[aquadibromido(3-methylpyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(H2O)2] (III), and bis(μ-4-methylpyridine N-oxide)bis[dibromidomethanol(4-methylpyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(CH3OH)2] (IV). All the compounds have one unique MnII atom and form a dimeric complex that contains two MnII atoms related by a crystallographic inversion center. Pseudo-octahedral six-coordinate manganese(II) centers are found in all four compounds. All four compounds form dimers of Mn atoms bridged by the oxygen atom of the PNO ligand. Compounds I, II and III exhibit a bound water of solvation, whereas compound IV contains a bound methanol molecule of solvation. Compounds I, III and IV exhibit the same arrangement of molecules around each manganese atom, ligated by two bromide ions, oxygen atoms of two PNO ligands and one solvent molecule, whereas in compound II each manganese atom is ligated by two bromide ions, one O atom of a PNO ligand and two water molecules with a second PNO molecule interacting with the complex via hydrogen bonding through the bound water molecules. All of the compounds form extended hydrogen-bonding networks, and compounds I, II, and IV exhibit offset π-stacking between PNO ligands of neighboring dimers.

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