Revisiting the assignment of innocent and non-innocent counterions in lanthanide(iii) solution chemistry
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Revisiting the assignment of innocent and non-innocent counterions in lanthanide(iii) solution chemistry. / Kofod, Nicolaj; Storm Thomsen, Maria; Nawrocki, Patrick; Sørensen, Thomas Just.
I: Dalton Transactions, Bind 51, Nr. 20, 2022, s. 7936-7949.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Revisiting the assignment of innocent and non-innocent counterions in lanthanide(iii) solution chemistry
AU - Kofod, Nicolaj
AU - Storm Thomsen, Maria
AU - Nawrocki, Patrick
AU - Sørensen, Thomas Just
PY - 2022
Y1 - 2022
N2 - Lanthanides are found in critical applications from display technology to renewable energy. Often, these rare earth elements are used as alloys or functional materials, yet access to them is through solution processes. In aqueous solutions, the rare earths are found predominantly as trivalent ions and charge balance dictates that counterions are present. The fast ligand exchange and lack of directional bonding in lanthanide complexes have led to questions regarding the speciation of Ln3+ solvates in the presence of various counterions and the distinction between innocent = non-coordinating and non-innocent = coordinating counterions. There is limited agreement as to which group counterions belong to, which led to this report. By using Eu3+ luminescence, it was possible to clearly distinguish between coordinating and non-coordinating ions. To interpret the results, it was required to bridge the descriptions of ion pairing and coordination. The data—in the form of Eu3+ luminescence spectra and luminescence lifetimes from solutions with varying concentrations of acetate, chloride, nitrate, sulfate, perchlorate and triflate—was contrasted to those obtained with ethylenediaminetetraacetic acid (EDTA4−), which allowed for the distinction between three Ln3+–anion interaction types. It was possible to conclude which counterions are truly innocent (e.g. ClO4− and OTf−) and which clearly coordinate (e.g. NO3− and AcO−). Finally, a considerable amount of data from systems studied under similar conditions allowed the minimum perturbation arising from the inner sphere or outer sphere coordination in Eu3+ complexes to be identified.
AB - Lanthanides are found in critical applications from display technology to renewable energy. Often, these rare earth elements are used as alloys or functional materials, yet access to them is through solution processes. In aqueous solutions, the rare earths are found predominantly as trivalent ions and charge balance dictates that counterions are present. The fast ligand exchange and lack of directional bonding in lanthanide complexes have led to questions regarding the speciation of Ln3+ solvates in the presence of various counterions and the distinction between innocent = non-coordinating and non-innocent = coordinating counterions. There is limited agreement as to which group counterions belong to, which led to this report. By using Eu3+ luminescence, it was possible to clearly distinguish between coordinating and non-coordinating ions. To interpret the results, it was required to bridge the descriptions of ion pairing and coordination. The data—in the form of Eu3+ luminescence spectra and luminescence lifetimes from solutions with varying concentrations of acetate, chloride, nitrate, sulfate, perchlorate and triflate—was contrasted to those obtained with ethylenediaminetetraacetic acid (EDTA4−), which allowed for the distinction between three Ln3+–anion interaction types. It was possible to conclude which counterions are truly innocent (e.g. ClO4− and OTf−) and which clearly coordinate (e.g. NO3− and AcO−). Finally, a considerable amount of data from systems studied under similar conditions allowed the minimum perturbation arising from the inner sphere or outer sphere coordination in Eu3+ complexes to be identified.
U2 - 10.1039/D2DT00565D
DO - 10.1039/D2DT00565D
M3 - Journal article
VL - 51
SP - 7936
EP - 7949
JO - Dalton Transactions (Online)
JF - Dalton Transactions (Online)
SN - 1477-9234
IS - 20
ER -
ID: 307368117