A TRLFS study on the complexation of Cm(iii) and Eu(iii) with 4-t-butyl-6,6′-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2′-bipyridine in a water/2-propanol mixture

Abstract

The complexation of Cm(III) and Eu(III) with 4-t-butyl-6,6'-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine (t-Bu-C2-BTBP) in water/2-propanol solution is studied. With increasing ligand concentration, 1 : 2 complexes [M(t-Bu-C2-BTBP)(2)(H(2)O)](3+) form from the solvated metal ions. The stability constants are log K(Cm(III)) = 11.1 and log K(Eu(III)) = 9.0. For both Cm(III) and Eu(III), the complexation reaction is both enthalpy and entropy driven. DeltaH(Cm(III)) is 11.7 kJ mol(-1) more negative than DeltaH(Eu(III)), whereas the entropy difference is negligible. This is in good agreement with t-Bu-C2-BTBP's selectivity in liquid-liquid extraction.

A TRLFS Study on the Complexation of CmIII and EuIII with 2,6‐Bis(5,6‐dipropyl‐1,2,4‐triazin‐3‐yl)pyridine in Water/Methanol Mixture

“…Thus we conclude the complex to be of the same composition as the complex which forms in 1-octanol. [16,17] As was shown for BTBP ligands, [23] the number of coordinated quenching molecules for Cm III cannot be calculated according to Equation (4) since additional quenching processes by intramolecular energy transfer between the Cm III ion and the organic ligand occur. The same applies to the BTP ligands.…”

“…[22] A similar study on BTBP proved that BTBP's selectivity is not confined to the organic phase only. [23] …”

Solvent Extraction and Fluorescence Spectroscopic Investigation of the Selective Am(III) Complexation with TS-BTPhen

“…The observed bathochromic shifts of the emission bands of the complex species are characteristic of the formation of a 1:1 and a 1:2 complex with a strong tetradentate N-donor ligand like TS-BTPhen [20,27,29] . Peak deconvolution was carried out, providing the spectra of the pure components shown in Figure 6.…”

Influence of diluent alkyl substitution on the extraction of Am(III) and Eu(III) by a 6,6´-bis(1,2,4-triazin-3-yl)-2,2´-bipyridine ligand dissolved in alkylated cyclohexanone diluents

“…A large number of ligands have been synthesized and tested in recent years as potential candidates in such a process [7][8][9][10][11]. Currently, the quadridentate nitrogen heterocyclic 6,6'-bis-(1,2,4-triazin-3-yl)-2,2'-bipyridine ligands (BTBPs) [12][13][14][15] show the most promising results. An important feature of these ligands is the pronounced effect of the type of diluent on the extraction properties of the solvent.…”