Structural analysis of natural deep eutectic solvents. Theoretical and experimental study

PISANO, PABLO L.; ESPINO, MAGDALENA; FERNÁNDEZ, MARÍA DE LOS ÁNGELES; SILVA, MARÍA F.; OLIVIERI, ALEJANDRO C.

MICROCHEMICAL JOURNAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 143 p. 252 - 258

0026-265X

A theoretical and experimental study was performed on natural deep eutectic solvents (NADES) formed by lacticacid-glucose (LGH), citric acid-fructose (CFH) and citric acid-glucose (CGH). The presence of nuclear Overhausereffect (NOE) in the proton nuclear magnetic resonance (1H NMR) spectra of the NADES was studied. The spatialproximity between the NADES components was experimentally confirmed by the detection of multiple NOEeffects in the dilutions analyzed. LGH showed the best outcome by partially maintaining its supramolecularstructure throughout the dilutions. In order to rationalize the intermolecular interactions generated among thecomponents, a theoretical study was performed using a density functional theory (DFT) computational method.A simplified dimeric model of the NADES was selected in order to achieve a rapid screening of the systemsearching for interactions between their constituents. In agreement with the experimental evidence, the calculationsallowed to confirm the spatial proximity, by finding at least two hydrogen bonds between the componentsof every NADES.