A TRLFS study on the complexation of novel BTP type ligands with Cm(iii)

Beele, Björn B.; Rüdiger, Elias C.; Schwörer, Felicitas; Müllich, Udo; Geist, Andreas; Panak, Petra J.

doi:10.1039/c3dt50536g

Cited by 23 publications

(39 citation statements)

References 39 publications

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“…As the solvent mixture contains a significant amount of acetonitrile, proton concentrations are noted as conditional pH values (pH C ). In contrast to the results of [Cm( n Pr-BTP) 3 ] 32 Liquid−Liquid Extraction. A high selectivity of BTTP for actinides(III) over lanthanides(III) when used as extracting agents was expected from the difference in Cm(III) and Eu(III) log β′ 3 values of 2.7 log units.…”

Section: ■ Results and Discussioncontrasting

confidence: 74%

A Complexation Study of 2,6-Bis(1-(p-tolyl)-1H-1,2,3-triazol-4-yl)pyridine Using Single-Crystal X-ray Diffraction and TRLFS

et al. 2015

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To develop a selective ligand for the separation of lanthanides(III) and actinides(III) the coordination chemistry of the chelating N-donor ligand 2,6-bis(1-(p-tolyl)-1H-1,2,3-triazol-4-yl)pyridine (BTTP) was investigated. The two isostructural lanthanide compounds [Ln(BTTP)3(OTf)3] (Ln = Eu (1), Sm (2); OTf = trifluoromethanesulfonate) were synthesized and fully characterized. The solid-state structures of both compounds were established by single-crystal X-ray diffraction. The complexation of Cm(III) and Eu(III) with BTTP in acetonitrile was studied using time-resolved laser fluorescence spectroscopy. With increasing BTTP concentration Cm(III) 1:2 and 1:3 complexes and Eu(III) 1:1 and 1:3 complexes are identified. The conditional stability constants of the 1:3 complex species with BTTP are log β3 = 14.0 for Cm(III) and log β3 = 10.3 for Eu(III). Both M(III) 1:3 complexes are prone to decomplexation with increasing acidity.

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Section: ■ Results and Discussioncontrasting

confidence: 74%

A Complexation Study of 2,6-Bis(1-(p-tolyl)-1H-1,2,3-triazol-4-yl)pyridine Using Single-Crystal X-ray Diffraction and TRLFS

et al. 2015

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“…The observed fluorescence lifetime of the [Cm(N 4 bipy) 3 ] complex is shorter than the fluorescence lifetime of the 1:3 Cm III -n Pr-BTP complexes 13 but longer than, for example, the lifetime values determined for Cm( n Pr-Tetrazine) 3 (τ = 164 μs) or Cm(Et-BDP) 3 (τ = 144 μs). 24 Moreover, the obtained curium(III) fluorescence lifetime values are significantly shorter than the calculated fluorescence lifetime of 1.3 ms expected for curium(III) with 9-fold coordination, in which all nine coordinating solvent molecules are replaced by three tridentate ligands. 53 The observed shorter fluorescence lifetime originates from a quenching process via intramolecular energy transfer from the metal ion excited state to a low-lying triplet state of the organic ligand.…”

Section: As Shown Inmentioning

confidence: 80%

6-(Tetrazol-5-yl)-2,2′-bipyridine: A Highly Selective Ligand for the Separation of Lanthanides(III) and Actinides(III)

et al. 2014

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The coordination structure in the solid state and solution complexation behavior of 6-(tetrazol-5-yl)-2,2'-bipyridine (HN4bipy) with samarium(III) was investigated as a model system for actinide(III)/lanthanide(III) separations. Two different solid 1:2 complexes, [Sm(N4bipy)2(OH)(H2O)2] (1) and [Sm(N4bipy)2(HCOO)(H2O)2] (2), were obtained from the reaction of samarium(III) nitrate with HN4bipy in isopropyl alcohol, resuspension in N,N-dimethylformamide (DMF), and slow crystallization. The formate anion coordinated to samarium in 2 is formed by decomposition of DMF to formic acid and dimethylamine. Time-resolved laser fluorescence spectroscopy (TRLFS) studies were performed with curium(III) and europium(III) by using HN4bipy as the ligand. Curium(III) is observed to form 1:2 and 1:3 complexes with increasing HN4bipy concentration; for europium(III), formation of 1:1 and 1:3 complexes is observed. Although the solid-state samarium complexes were confirmed as 1:2 species the 1:2 europium(III) solution complex in ethanol was not identified with TRLFS. The determined conditional stability constant for the 1:3 fully coordinated curium(III) complex species is more than 2 orders of magnitude higher than that for europium(III) (log β3[Cm(N4bipy)3] = 13.8 and log β3[Eu(N4bipy)3] = 11.1). The presence of added 2-bromodecanoic acid as a lipophilic anion source reduces the stability constant for formation of the 1:2 and 1:3 curium(III) complexes, but no ternary complexes were observed. The stability constants for the 1:3 metal ion-N4bipy complexes equate to a theoretical separation factor, SF(Cm(III)/Eu(III)) ≈ 500. However, the low solubility of the HN4bipy ligand in nonpolar solvents typically used in actinide-lanthanide liquid-liquid extractions prevents its use as a partitioning extractant until a more lipophilic HN4bipy-type ligand is developed.

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“…Quantum-chemical calculations have been used alongside analytical methods to investigate the differences in structure between selected Ln(III) and An(III) complexes. A combined effort of electrospray mass spectroscopy 8,9 , time-resolved laser-induced fluorescence spectroscopy (TRLFS) [10][11][12][13][14][15][16] , X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS) [15][16][17][18][19][20][21] with complementary density functional theory (DFT) studies 16,18 have probed the structure of [Ln/An(BTP) n ] 3+ (n = 1-3), with a general focus on the complexes of Ln = Eu,…”

Section: Introductionmentioning

confidence: 99%

Topological Study of Bonding in Aquo and Bis(triazinyl)pyridine Complexes of Trivalent Lanthanides and Actinides: Does Covalency Imply Stability?

2016

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The geometrical and electronic structures of Ln[(HO)] and [Ln(BTP)], where Ln = Ce-Lu, have been evaluated at the density functional level of theory using three related exchange-correlation (xc-)functionals. The BHLYP xc-functional was found to be most accurate, and this, along with the B3LYP functional, was used as the basis for topological studies of the electron density via the quantum theory of atoms in molecules (QTAIM). This analysis revealed that, for both sets of complexes, bonding was almost identical across the Ln series and was dominated by ionic interactions. Geometrical and electronic structures of actinide (An = Am, Cm) analogues were evaluated, and [An(HO)] + [Ln(BTP)] → [Ln(HO)] + [An(BTP)] exchange reaction energies were evaluated, revealing Eu ↔ Am and Gd ↔ Cm reactions to favor the An species. Detailed QTAIM analysis of Eu, Gd, Am, and Cm complexes revealed increased covalent character in M-O and M-N bonds when M = An, with this increase being more pronounced in the BTP complexes. This therefore implies a small electronic contribution to An-N bond stability and the experimentally observed selectivity of the BTP ligand for Am and Cm over lanthanides.

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A TRLFS study on the complexation of novel BTP type ligands with Cm(iii)

Cited by 23 publications

References 39 publications

A Complexation Study of 2,6-Bis(1-(p-tolyl)-1H-1,2,3-triazol-4-yl)pyridine Using Single-Crystal X-ray Diffraction and TRLFS

A Complexation Study of 2,6-Bis(1-(p-tolyl)-1H-1,2,3-triazol-4-yl)pyridine Using Single-Crystal X-ray Diffraction and TRLFS

6-(Tetrazol-5-yl)-2,2′-bipyridine: A Highly Selective Ligand for the Separation of Lanthanides(III) and Actinides(III)

Topological Study of Bonding in Aquo and Bis(triazinyl)pyridine Complexes of Trivalent Lanthanides and Actinides: Does Covalency Imply Stability?

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