Importance of an intramolecular 1,5-CH…O interaction and intermolecular interactions as factors determining conformational equilibria in 1,2-dimethoxyethane: a matrix-isolation infrared spectroscopic study

A molecular dynamics model of the amorphous regions of polyethylene oxide

“…27 was made using a model which did not include explicit coulomb interactions. This is discussed in more detail below.͒ The helical structure of the chains in the crystalline form of polyethylene oxide 28 and the fact that the lowest energy conformer of the dimer is tgt in normal gases, solutions, melts and crystals [29][30][31][32] may suggest that the torsional forces are such that the tgt conformer is preferred. On the other hand, there has been considerable recent debate about the origin of this preference for twisted structures, and several authors 16,33 have suggested that the preference for gauche configurations in the crystal and for the dimer in polar environments may be a result of the effects of the polar environment.…”

Terahertz time-domain and Raman spectroscopy of the sulfur-containing peptide dimers: Low-frequency markers of disulfide bridges

“…Both theoretical and experimental works are devoted to the disulfide bridges in proteins and model compounds [11][12][13][14]. The potential energy profiles are calculated in terms of the valence angles in the bridges [15,16]. The distributions of the protein molecules with respect to the corresponding angles are presented in reference [17].…”

A molecular dynamics simulation study with a combined quantum mechanical and molecular mechanical potential energy function: Solvation effects on the conformational equilibrium of dimethoxyethane

“…4 There exists ample evidence, both theoretical and experimental, that in the gas phase the ttt ͑all-trans͒ conformer of DME is the most stable form. 1,5,6 The energy difference between the tgt ͑trans-gauche-trans͒ and the ttt conformers in the gas phase has been calculated at different levels of theory to be 2-3 kJ/mol favoring ttt ͑in this report, all relative energy and free energy values are with respect to those of the ttt conformer, which are taken to be zero͒. Once DME is in aqueous solution or surrounded by a polarizable medium, its central dihedral angle prefers the gauche conformation.…”

“…[1][2][3] Similarly, polyethyleneoxide, of which DME is the simplest analog, and other compounds which contain the O-CH 2 -CH 2 -O motif, prefer a gauche conformation around the CH 2 -CH 2 bond in the crystal, in the melt, and in solution. 4 There exists ample evidence, both theoretical and experimental, that in the gas phase the ttt ͑all-trans͒ conformer of DME is the most stable form.…”