Assessing the hydrotropic effect in the presence of electrolytes: competition between solute salting-out and salt-induced hydrotrope aggregation.

Autor: Martins AC; CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal. nicolas.schaeffer@ua.pt., Benfica J; CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal. nicolas.schaeffer@ua.pt., Peréz-Sanchéz G; CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal. nicolas.schaeffer@ua.pt., Shimizu S; York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, UK., Sintra TE; CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal. nicolas.schaeffer@ua.pt., Schaeffer N; CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal. nicolas.schaeffer@ua.pt., Coutinho JAP; CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal. nicolas.schaeffer@ua.pt.
Jazyk: angličtina
Zdroj: Physical chemistry chemical physics : PCCP [Phys Chem Chem Phys] 2022 Sep 21; Vol. 24 (36), pp. 21645-21654. Date of Electronic Publication: 2022 Sep 21.
DOI: 10.1039/d2cp00749e
Abstrakt: Water solubility enhancement is a long-standing challenge in a multitude of chemistry-related fields. Hydrotropy is a simple and efficient method to improve the solubility of hydrophobic molecules in aqueous media. However, the mechanism behind this phenomenon remains controversial. Herein the impact of salt doping on the hydrotropy phenomenon is determined experimentally using the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([C 4 mim]Cl) as a hydrotope and vanillin as a solute. Hydrophobic interactions were found to be central to the aggregation of the hydrotrope around the solute, and seem to drive hydrotropy. Furthermore, 1 H-NMR analysis indicates that hydrotrope-solute interactions present a degree of site-specificity. The addition of chloride salts in the presence of higher IL concentrations promotes a greater relative decrease of the vanillin solubility than in the corresponding system without the IL. This was assigned to the negative impact of increased hydrotrope pre-aggregation in the presence of inorganic salts. The results were rationalised using statistical thermodynamics through which hydrotrope aggregation prior to solute addition is shown to be detrimental to the hydrotropic effect, seemingly confirming solute-induced clustering of the hydrotrope to be the predominant mechanism of hydrotropy.
Databáze: MEDLINE
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