Electrostatic manifestation of micro-heterogeneous solvation structures in deep-eutectic solvents: a spectroscopic approach

TitleElectrostatic manifestation of micro-heterogeneous solvation structures in deep-eutectic solvents: a spectroscopic approach
Publication TypeJournal Article
Year of Publication2020
AuthorsChatterjee, S, Haldar, T, Ghosh, D, Bagchi, S
JournalJournal of Physical Chemistry B
Volume124
Issue18
Pagination3709-3715
Date PublishedMAY
Type of ArticleArticle
ISSN1520-6106
Abstract

Deep eutectic solvents have emerged as inexpensive green alternatives to conventional solvents for diverse applications in chemistry and biology. Despite their importance as useful media in various applications, little is known about the microscopic solvation structures of deep eutectic solvents around solutes. Herein, we show that the electrostatic field, which can be estimated both from infrared experiments and theory, can act as a unified concept to report on the microscopic heterogeneous solvation of deep eutectic solvents. Using a fluorophore containing the carbonyl moiety as the solute and the electrostatic field as a descriptor of the solvation structure of the deep eutectic solvents, we report the residue-specific distribution, orientation, and hydrogen bonding in deep eutectic solvents constituting of choline chloride and alcohols of varying chain-lengths. We observe that an increase in alcohol chain-length not only affects the alcohol's propensity to form hydrogen bond to the solute but also alters the spatial arrangement of choline cations around the solute, thereby leading to a microheterogeneity in the solvation structure. Moreover, to extend our electrostatic field based strategy to other deep eutectic solvents, we report an emission spectroscopy based method. We show that this method can be applied, in general, to all deep eutectic solvents, irrespective of their constituents. Overall, this work integrates experiments with molecular dynamics simulations to provide insights into the heterogeneous DES solvation.

DOI10.1021/acs.jpcb.9b11352
Type of Journal (Indian or Foreign)

Foreign

Impact Factor (IF)

2.857

Divison category: 
Physical and Materials Chemistry

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