Complexation of Cm(III) and Eu(III) with a hydrophilic 2,6-bis(1,2,4-triazin-3-yl)-pyridine studied by time-resolved laser fluorescence spectroscopy

Christian M Ruff; Udo Müllich; Andreas Geist; Petra J Panak

doi:10.1039/c2dt31748f

Complexation of Cm(III) and Eu(III) with a hydrophilic 2,6-bis(1,2,4-triazin-3-yl)-pyridine studied by time-resolved laser fluorescence spectroscopy

Dalton Trans. 2012 Dec 28;41(48):14594-602. doi: 10.1039/c2dt31748f.

Authors

Christian M Ruff¹, Udo Müllich, Andreas Geist, Petra J Panak

Affiliation

¹ Karlsruher Institut für Technologie, Institut für Nukleare Entsorgung, P. O. Box 3640, 76021 Karlsruhe, Germany. Christian.ruff@kit.edu

PMID: 23018544
DOI: 10.1039/c2dt31748f

Abstract

The complexation of Cm(III) and Eu(III) with 2,6-bis(5,6-di(sulfophenyl)-1,2,4-triazin-3-yl)pyridine (aq-BTP) is studied in water at pH 3.0 applying time-resolved laser fluorescence spectroscopy. With increasing ligand concentration [M(H(2)O)(9-3n)(aq-BTP)(n)] (M = Cm(III)/Eu(III), n = 1, 2, 3) complex species are spectroscopically identified. The conditional stability constants of the M(III) 1 : 3 complex species with aq-BTP are log β(03) = 12.2 for Cm(III) and log β(03) = 10.2 for Eu(III). The complexation reaction is enthalpy- and entropy-driven for both metal ions, while the enthalpy change ΔH(03) is 9.7 kJ mol(-1) more negative for Cm(III); changes in ΔS(03) are marginal. The difference in ΔG(03) of -12.7 kJ mol(-1) between the formation of the [M(aq-BTP)(3)] complexes agrees with aq-BTP's selectivity in liquid-liquid extraction studies.