نتایج جستجو برای: non hydrogen bonded interaction
تعداد نتایج: 1958437 فیلتر نتایج به سال:
Although it is widely accepted that the local structure of liquid water has tetrahedral arrangements of molecules ordered by hydrogen bonds, the mechanism by which water molecules switch hydrogen-bonded partners remains unclear. In this mechanism, the role of nonhydrogen-bonded configurations (NHBs) between adjacent molecules is of particular importance. A molecule may switch hydrogen-bonding p...
Hydrogen-bonded and stacked structures of adenine-thymine and guanine-cytosine nucleotide base pairs, along with their methylated analogues, are examined with the ab inito based general effective fragment potential (EFP2) method. A comparison of coupled cluster with single, double, and perturbative triple (CCSD(T)) energies is presented, along with an EFP2 energy decomposition to illustrate the...
The bonding between two neutral aromatic compounds, especially small ones, has been controversially debated in the last decades, and terms like “π-stacking” had to be revised. Surprisingly, despite of many experimental computational work, there is still no clear consensus about structure pyridine dimer. In this for different isomeric forms dimer, structures were elucidated by combining high-res...
The title compound, C(7)H(6)BrN(3)O, was obtained from the reaction of 6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one with methyl iodide. All non-H atoms lie in a common plane [r.m.s deviation = 0.017 (1) Å]. The amino group is a hydrogen-bond donor to the carbonyl group of an inversion-related mol-ecule, the pair of hydrogen bonds giving rise to a hydrogen-bonded dimer.
We develop a phenomenological vector model of polar liquids capable to describe aqueous interactions of macroscopic bodies. It is shown that a strong, long-range and orientationally dependent interaction between macroscopic objects appears as a result of competition between short-range (hydrogen bonding) and the long-range dipole-dipole interactions of the solvent molecules. Spontaneous polariz...
Oxidation of methionine disrupts the structure and function of a range of proteins, but little is understood about the chemistry that underlies these perturbations. Using quantum mechanical calculations, we found that oxidation increased the strength of the methionine-aromatic interaction motif, a driving force for protein folding and protein-protein interaction, by 0.5-1.4 kcal/mol. We found t...
A new bulky pyrene-derived elongated cross-shaped organic scaffold was successfully incorporated into a highly porous, noninterpenetrated square-grid copper(II)-organic framework material with the unprecedentedly huge dimensions of 25.5 x 25.5 A(2), while the layer-to-layer NH...N interaction leads to a unique hydrogen-bonded 6(4).8(2)-nbo net.
The empirical rules for estimating molar rotations of carbohydrate structures proposed by Whiffen and elaborated by Brewster provided interpretations of solvent effects on optical rotation with changes in conformational equilibria which in certain cases were confirmed by n.m.r. Conversely, it was found that only slight changes in rotation occur on changing the solvent for conformationally rigid...
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