Jump to main content
Jump to site search


Complexation thermodynamics of tetraalkyl diglycolamides with trivalent f-elements in ionic liquids: spectroscopic, microcalorimetric and computational studies

Author affiliations

Abstract

The thermodynamics of lanthanide complexation with a series of diglycolamides (DGAs) containing varying alkyl chain lengths (methyl, ethyl, n-butyl and n-hexyl) was studied in [C4mim][Tf2N], a room temperature ionic liquid. The stability constants, enthalpies and entropies of complexation were determined by spectrophotometry and calorimetry. All the DGA ligands formed a 1 : 3 (Nd3+/DGA) complex as the limiting species, and their stability constants increased linearly with increasing alkyl chain length. The stability constants of the Nd3+/DGA complexes are orders of magnitude higher in [C4mim][Tf2N] as compared to those observed in aqueous medium. For all the complexes, the enthalpy of complexation was negative with a positive entropy change, indicating that the complexation was driven by both enthalpy and entropy. The enthalpy changes observed in [C4mim][Tf2N] medium were more exothermic than those in the aqueous medium. Fluorescence lifetime data indicated that the complexation proceeded via the replacement of water molecules from the primary coordination sphere of the metal ion. DFT calculations were performed on the structures of the different Nd3+/tetramethyl DGA (TMDGA) complexes, and the corresponding free energies in both gas and solution phases were calculated. Insights into the structural features by DFT studies confirmed that the nature of Ln3+/DGA complexes formed in [C4mim][Tf2N], n-dodecane, and aqueous medium and that in the crystalline state is identical.

Graphical abstract: Complexation thermodynamics of tetraalkyl diglycolamides with trivalent f-elements in ionic liquids: spectroscopic, microcalorimetric and computational studies

Back to tab navigation

Supplementary files

Publication details

The article was received on 19 Oct 2017, accepted on 29 Nov 2017 and first published on 29 Nov 2017


Article type: Paper
DOI: 10.1039/C7NJ03925E
Citation: New J. Chem., 2018, Advance Article
  •   Request permissions

    Complexation thermodynamics of tetraalkyl diglycolamides with trivalent f-elements in ionic liquids: spectroscopic, microcalorimetric and computational studies

    S. A. Ansari, P. K. Mohapatra, Sk. Musharaf Ali, N. Rawat, B. S. Tomar, A. Leoncini, J. Huskens and W. Verboom, New J. Chem., 2018, Advance Article , DOI: 10.1039/C7NJ03925E

Search articles by author

Spotlight

Advertisements