A study of OH···O hydrogen bonds along various isolines in 2-ethyl-1-hexanol. Temperature or pressure - which parameter controls their behavior?

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 283
• Main Authors: Hachuła, Barbara, Kamińska, Ewa, Koperwas, Kajetan, Wrzalik, Roman, Jurkiewicz, Karolina, Tarnacka, Magdalena, Scelta, Demetrio, Fanetti, Samuele, Pawlus, Sebastian, Paluch, Marian, Kamiński, Kamil
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2022
• Subjects: Hydrogen bond; Intramolecular dynamics; Isolines; Pressure; Temperature; Intramolecular dynamics; Temperature; Isolines; Pressure; Hydrogen bond
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2022.121726

[Display omitted] •The unique high-pressure infrared, dielectric, and volumetric data were analyzed.•T and p dependence of H-bonding energy along various isolines was studied.•A phase diagram of 2E1H, identifying isolines in the T-p plane, was constructed.•T controls the intramolecular dynamics of OH units in 2E1H.•The impact of density fluctuation grows with increasing T and weakening of HBs. The nature of H-bonding interactions is still far from being understood despite intense experimental and theoretical studies on this subject carried out by the leading research centers. In this paper, by a combination of unique high-pressure infrared, dielectric and volumetric data, the intramolecular dynamics of hydroxyl moieties (which provides direct information about H-bonds) was studied along various isolines, i.e., isotherms, isobars, isochrones, and isochores, in a simple monohydroxy alcohol (2-ethyl-1-hexanol). This allowed us to discover that the temperature controls the intermolecular hydrogen bonds, which then affect the intramolecular dynamics of OH units. Although the role of density fluctuations gets stronger as temperature rises. We also demonstrated a clear connection between the intra- and intermolecular dynamics of the associating liquid at high pressure. The data reported herein open a new perspective to explore this important aspect of the glass transition phenomenon and understand H-bonding interactions at varying thermodynamic conditions.