Halogen bonding (XB) non-covalent interactions can be observed in compounds containing chlorine, bromine, or iodine which can form directed close contacts of the type R1-XY-R2, where the halogen X acts as a Lewis acid and Y can be any electron donor moiety including electron lone pairs on hetero atoms such as O and N, or π electrons in olefin double bonds and aromatic conjugated systems. In thi...

Dynamical properties of F –water and Cl –water hydrogen bond molecular dynamics simulations, in which the whole first hydration D95V+, 6-31+G and D95V++ basis sets for F , Cl and water, respe and shifts in the corresponding bending and stretching frequencies as ing the ions, F clearly acts as a structure-maker , while Cl solvat ments of the hydrogen bonds. 2005 Elsevier B.V. All rights reserved.

BACKGROUND The formation of intramolecular hydrogen bonds (IHBs) may induce the remarkable changes in molecular physicochemical properties. Within the framework of the extended solvent-contact model, we investigate the effect of implementing the IHB interactions on the accuracy in estimating the molecular hydration free energies. RESULTS The performances of hydration free energy functions inc...

The hydration numbers of typical aprotic polar substances bearing dipole moments larger than 3 D, such as nitro compounds and nitriles, were precisely determined in aqueous solution using high frequency dielectric relaxation techniques up to a frequency of 50 GHz at 25 °C. The hydration number is one of the most quantitative parameters for determining the hydrophilicity or hydrophobicity of a c...

The thermal folding of hydrated lysozyme has been investigated by means of the high resolution nuclear magnetic resonance (NMR) technique. The proton NMR signal belonging to the biomolecule hydration water (hydration level h = 0.3) was analyzed with the aim to explore the protein structural changes as well as to verify if water plays a role in this biological basic phenomenon. In such a way, we...

Hydration of gaseous guanidinium (Gdm+) with up to 100 water molecules attached was investigated using infrared photodissociation spectroscopy in the hydrogen stretch region between 2900 and 3800 cm-1. Comparisons to IR spectra of low-energy computed structures indicate that at small cluster size, water interacts strongly with Gdm+ with three inner shell water molecules each accepting two hydro...

Kosmotropic (order-making) and chaotropic (order-breaking) co-solvents influence stability and biochemical equilibrium in aqueous solutions of proteins, acting indirectly through the structure and dynamics of the hydration water that surrounds the protein molecules. We have investigated the influence of kosmotropic and chaotropic co-solvents on the hydrogen bonding network dynamics of both bulk...

Introduction: Pyroclastic deposits on the Moon represent early lunar volcanic processes [1], and models of explosive volcanism indicate that the range of pyroclastic deposits is proportional to volatile content [2]. Therefore, the distribution of lunar pyroclastic deposits and their estimated water content can provide indirect information on the distribution of volatiles in magma source regions...

Since the pioneering works of Pethig, Grant, and Wüthrich on a protein hydration layer, many studies have been devoted to find out if there are any "general and universal" characteristic features that can distinguish water molecules inside the protein hydration layer from bulk. Given that the surface itself varies from protein to protein, and that each surface facing the water is heterogeneous,...

In DNA, base pairs are involved in two reciprocal interactions: interbase hydrogen bonds and stacking. Furthermore, base pairs also undergo the effects of the external entities present in the biological environment, such as water molecules and cations. In this contribution, the double spontaneous mutation has been studied with hybrid theoretical tools in a DNA-embedded guanine-cytosine model ac...