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

Abstract

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.

An Insight into the Complexation of Trivalent Americium Vis‐à‐Vis Lanthanides with Bis(1,2,4‐triazinyl)bipyridine Derivatives

“…The log β values are higher for Am 3+ than for the Ln 3+ ions studied, indicating the selectivity of this class of ligands for Am 3+ over the Ln 3+ ions. In the cases of terdentate N‐donor ligands, namely BTP, PyTri derivatives, however, higher stoichiometric complexes were observed for Am 3+ than for the Ln 3+ ions.…”

“…Lewis et al explored a bis(1,2,4‐triazinyl)phenanthroline (R‐BTPhen; Figure ) derivative also for this purpose . Bis(triazolyl)pyridines (PyTri; Figure ) are another class of ligands, which were also explored for the selective extraction and complexation studies of the trivalent actinides over the lanthanides . Keifer et al[23a] have synthesized a p ‐tolyl derivative of PyTri for the selective complexation/extraction of An 3+ over Ln 3+ .…”

“…Bis(triazolyl)pyridines (PyTri; Figure ) are another class of ligands, which were also explored for the selective extraction and complexation studies of the trivalent actinides over the lanthanides . Keifer et al[23a] have synthesized a p ‐tolyl derivative of PyTri for the selective complexation/extraction of An 3+ over Ln 3+ . A time‐resolved laser‐induced fluorescence spectroscopic (TRLFS) study indicated that Cm 3+ formed 1:2 and 1:3 complexes with log β values of 9.7 and 14.0, respectively.…”

“…Eu 3+ , on the other hand, formed 1:1 and 1:3 complexes with log β values of 2.8 and 10.3, respectively, indicating a high selectivity of PyTri derivatives for An 3+ over Ln 3+ . Macerata et al[23b] have further explored the potential of PyTri ligands by using hydrophilic derivatives and demonstrated stripping of Am 3+ with a high selectivity over Eu 3+ from an organic medium containing diglycolamides as the extractant. They observed differential speciation for Am 3+ and Eu 3+ with metal/ligand ratios of 1:2 and 1:1, respectively.…”

Selective Extraction of Americium(III) over Europium(III) Ions with Pyridylpyrazole Ligands: Structure–Property Relationships

“…Recently, tridentate N ligands of the 2,6‐bis(triazolyl)pyridine type exhibited particular selectivity for Am III . Kiefer et al examined the complexation behaviors of 2,6‐bis[1‐( p ‐tolyl)‐1 H ‐1,2,3‐triazol‐4‐yl]pyridine (BTTP) with Eu III , Sm III , and Cm III ions through single‐crystal X‐ray diffraction and time‐resolved laser fluorescence spectroscopy (TRLFS) . Afterwards, Macerata et al found that hydrophilic clicked 2,6‐bis(triazolyl)pyridines could selectively strip the actinides from a diglycolamide‐containing kerosene solution into an acidic aqueous phase .…”