Hydrogen Bonding in the Liquid State of Linear Alcohols: Molecular Dynamics and Thermodynamics

Jindal, A and Vasudevan, S (2020) Hydrogen Bonding in the Liquid State of Linear Alcohols: Molecular Dynamics and Thermodynamics. In: Journal of Physical Chemistry B, 124 (17). pp. 3548-3555.

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Abstract

Linear monohydroxy alcohols are strongly hydrogen-bonded liquids that are considered to be homologues of water. Here, we report ab initio molecular dynamics simulations of the liquid alcohols, methanol to pentanol, and from the combined radial-angular probability distribution of the intermolecular O···O distances and HO···O angles determine the geometrical parameters that define the hydrogen bonds in these systems. The key feature of hydrogen bonds in the liquid alcohols, irrespective of the size of the alkyl group, is the strong orientation dependence with the donor-acceptor HO···O angle being close to zero, similar to that observed in liquid water. Hydrogen bond formation is consequently considered to be the passage from a state where donor-acceptor pairs show no preferred orientation to one where they are almost linear. The potential of mean force, the reversible work associated with this process, is computed from the pair probability density distributions obtained from the simulations and that for a hypothetical state where donor-acceptor pairs are randomly oriented. We find that the magnitude of the free energy for hydrogen bond formation is maximum for ethanol and show that this arises from a larger electrostatic contribution to hydrogen bond formation in ethanol as compared to the other alcohols.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry B
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society.
Keywords:	Angular distribution; Ethanol; Free energy; Geometry; Liquids; Molecular dynamics, Ab initio molecular dynamics simulation; Donor-acceptor pairs; Electrostatic contributions; Hydrogen bonded liquids; Hydrogen-bond formation; Potential of mean force; Preferred orientations; Probability density distribution, Hydrogen bonds
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	06 Feb 2023 09:33
Last Modified:	06 Feb 2023 09:33
URI:	https://eprints.iisc.ac.in/id/eprint/79920

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