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Liquid structure and dynamics in the choline acetate:urea 1:2 deep eutectic solvent

DOI: 10.1063/5.0054048 DOI Help

Authors: Alessandro Triolo (Consiglio Nazionale delle Ricerche, (ISM-CNR)) , Maria Enrica Di Pietro (Politecnico di Milano) , Andrea Mele (Politecnico di Milano) , Fabrizio Lo Celso (Nazionale delle Ricerche (ISM-CNR); Università di Palermo) , Martin Brehm (Martin-Luther-Universität Halle–Wittenberg) , Valerio Di Lisio (University of Rome Sapienza) , Andrea Martinelli (University of Rome Sapienza) , Philip Chater (Diamond Light Source) , Olga Russina (Consiglio Nazionale delle Ricerche (ISM-CNR); University of Rome Sapienza)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Chemical Physics , VOL 154

State: Published (Approved)
Published: June 2021
Diamond Proposal Number(s): 27222

Open Access Open Access

Abstract: We report on the thermodynamic, structural, and dynamic properties of a recently proposed deep eutectic solvent, formed by choline acetate (ChAc) and urea (U) at the stoichiometric ratio 1:2, hereinafter indicated as ChAc:U. Although the crystalline phase melts at 36–38 °C depending on the heating rate, ChAc:U can be easily supercooled at sub-ambient conditions, thus maintaining at the liquid state, with a glass–liquid transition at about −50 °C. Synchrotron high energy x-ray scattering experiments provide the experimental data for supporting a reverse Monte Carlo analysis to extract structural information at the atomistic level. This exploration of the liquid structure of ChAc:U reveals the major role played by hydrogen bonding in determining interspecies correlations: both acetate and urea are strong hydrogen bond acceptor sites, while both choline hydroxyl and urea act as HB donors. All ChAc:U moieties are involved in mutual interactions, with acetate and urea strongly interacting through hydrogen bonding, while choline being mostly involved in van der Waals mediated interactions. Such a structural situation is mirrored by the dynamic evidences obtained by means of 1H nuclear magnetic resonance techniques, which show how urea and acetate species experience higher translational activation energy than choline, fingerprinting their stronger commitments into the extended hydrogen bonding network established in ChAc:U.

Journal Keywords: Monte Carlo methods; Chemical bonding; High-energy X rays; Synchrotrons; Nuclear magnetic resonance spectroscopy; Glass transitions; Deep eutectic solvents

Subject Areas: Chemistry

Instruments: I15-1-X-ray Pair Distribution Function (XPDF)

Added On: 30/06/2021 08:37


Discipline Tags:

Physical Chemistry Chemistry Organic Chemistry

Technical Tags:

Scattering Total Scattering