Imim-DEHP reverse micelles investigated with two molecular probes reveals how are the interfacial properties and the coordination behavior of the surfactant

DIB, NAHIR; SILBER, JUANA J.; CORREA, N. MARIANO; FALCONE, R. DARIO

JOURNAL OF MOLECULAR LIQUIDS

ELSEVIER SCIENCE BV

Año: 2020

0167-7322

Aqueous reverse micelles (RMs) generated with the ionic liquid (IL)-surfactant1-methylimidazolium bis-(2-ethylhexyl)phosphate (imim-DEHP) and the biocompatiblesolvents methyl laurate (ML) and isopropyl myristate (IPM) were studied through the use oftwo molecular probes: the IL 3,6-bis(dimethylamino) acridinium bis-(2-ethylhexyl) phosphate(AOBH-DEHP) and the complex N,N,N`,N`-tetramethylethylenediaminecopper(II)acetylacetonate tetraphenylborate ([Cu(acac)(tmen)][B(C6H5)4]). The techniquesused were absorption and emission spectroscopy. Specifically, we explore how the chemicalnature of the surfactant alters RMs properties such as micropolarity, specific interactions, andrestricted motion environment. Furthermore, we analyzed how the imim-DEHP assemblyaffects the coordination behavior of the surfactant. The results show that the interfacialproperties of the imim-DEHP RMs are dominated by the chemical nature of the surfactant asa consequence of a strong interaction of the imim+cation with water molecules. Because ofthis strong interaction imim+-water, the anion DEHP-hasan enhanced capacity to coordinateion Cu+2 in comparison when the surfactant is in a homogeneous medium. Also, our resultsdemonstrate that the strength of the anion DEHP-as a ligand in imim-DEHP RMs can bemodulated both through the choice of the external solvent and the water content. In summary,the obtained results are very interesting for the potential use of the imim-DEHP RMs asnanoreactors and in metals extraction.