Does High Pressure Induce Structural Reorganization in Linear Alcohols? A Computational Answer

Abstract

We present an exhaustive computational study on the effect of high pressure on normal alcohols with alkyl chains with lengths of three-to-eight carbon atoms. 1-Propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol were studied by using classical molecular dynamics simulations and applying pressures in the range of 1 to 10 bar. The results of our calculations show that high-pressure values affect the structure significantly. In particular, we have observed a marked difference in behavior for alcohols with chain lengths below six and those with more than six or seven carbon atoms, with hexanol and heptanol being boundary cases. We have named the model with the most shrunk alkyl chains as the Asclepius form inspired by the Rod of Asclepius, the universally known symbol of medicine, in which a snake is coiled around a rod.

Relationship between Nanoscale Supramolecular Structure, Effectiveness of Hydrogen Bonds, and Appearance of Debye Process

“…Such a scenario, together with the explanation of contributions of the different molecular interactions to the diffraction prepeak in nalcohols, was described in the literature. 43 The main diffraction peak position, Q mp , estimated at 1.36 Å −1 for 2E1HOH, is caused by a correlation between the nearest-neighbor molecules, and the associated first intermolecular distance, d mp = 2π/Q mp , is 4.62 Å. The diffraction pattern of 2E1HNH 2 shows the main diffraction peak at Q mp ≈ 1.34 Å −1 and also a prepeak at Q pp ≈ 0.35 Å −1 (Figure 3b).…”

Enhanced Li+ Transport in Ionic Liquid‐Based Electrolytes Aided by Fluorinated Ethers for Highly Efficient Lithium Metal Batteries with Improved Rate Capability

“…More interesting is the behavior of the pre-peak. This feature is usually not observed for isotropic liquids, that is, BTFE, with the exception of some strongly amphiphilic molecular liquids [40,41] and some ILs. [42,43] This peak is due to supramolecular interactions with specific characteristic lengths in the order of a few nanometers.…”

On the X-ray Scattering Pre-peak of Linear Mono-ols and the Related Microstructure from Computer Simulations

“…There have been several investigations of the origin of the pre-peak, which is now generally interpreted as corresponding to the existence of short chain-like or ring-like clusters of hydrogen-bonded hydroxyl groups. Interestingly, this conclusion was reached by several different routes: the direct reconstruction of the pre-peak as a diffraction pattern from assumed cluster shapes, , the thermodynamic route of matching the internal energy with H-bond associations, a hard-sphere model for the spherical cluster aggregates, and, more recently, various computer simulation analyses. − All these descriptions emphasize a causal link between the existence of clusters formed by the hydroxyl groups and the pre-peak in I ( k ). This is directly inspired from the fact that radiation is scattered-off objects, usually atoms or molecules; hence, specific features in I ( k ), such as the pre-peak, should refer to the existence of corresponding meta-objects, such as clusters, aggregates, or self-assembled structures .…”