Coordination abilities of Good's buffer ionic liquids toward europium(III) ion in aqueous solution. (March 2016)

• Record Type: Journal Article
• Authors: Taha, Mohamed; Khan, Imran; Coutinho, João A.P.
• Is Part Of: Journal of chemical thermodynamics. Volume 94(2016:Mar.)
• Page Start: 152
• Page End: 159
• Publication Date: 2016-03
• Subjects: Good's buffers ionic liquids -- Eu(III) complexes -- Tricine -- Protonation constants -- Stability constants; Thermodynamics -- Periodicals; Thermochemistry -- Periodicals; Thermodynamique -- Périodiques; Thermochimie -- Périodiques; Thermochemistry; Thermodynamics; Periodicals; 541.369
• DOI: 10.1016/j.jct.2015.11.003
• Languages: English
• ISSNs: 0021-9614

Abstract

Graphical abstract: Highlights: The protonation constants of tricine-based GB-ILs were determined. The stability constants of tricine-based GB-ILs with Eu(III) were determined. The studied GB-ILs have formed strong complexes with Eu(III) ion. The species distribution diagrams of these complexes were computed. The geometries of Eu-tricine complexes were characterized by DFT. Abstract: Good's buffer ionic liquids (GB-ILs) are new class of ILs with self-buffering capacity at the physiological pH range for biological research. GB-ILs are formed by the combination of Good's buffers as anions and various organic bases as counter ions. In this work, the complexation of europium(III) ion with tricine and tricine-based GB-ILs, tetramethylammonium tricinate, tetraethylammonium tricinate, tetrabutylammonium tricinate, cholinium tricinate, and 1-ethyl-3-methylimidazolium tricinate in aqueous solution were determined potentiometrically at T = 298.2 K and ionic strength I = 0.1 mol · dm −3 NaNO3 . The protonation constants of the studied ligands (L) and their overall stability constants ( lg β ) with Eu(III) were determined. The best model that fit the potentiometric data was consisted of six main species, EuL 2 +, EuL 2 +, EuL 3, EuH - 1 L +, EuH - 2 L 2 -, and EuH - 3 L 3 3 - . The lg β Eu ( tricine ), lg β Eu ( tricine ) 2, and lg β Eu ( tricine ) 3 are 5.75, 9.51, and 12.79, respectively. The overall stability constants ( lg β ) of tricine-based GB-ILs were found to be greater than those of tricine. The species distribution diagrams of these complexes were calculated and discussed in terms of percent Eu(III) and pH. We present a density functional theory (DFT) study to understand tricine chelating to Eu(III).