TY - JOUR

T1 - Mapping the distribution of electronic states within the 5D4 and 7F6 levels of Tb3+ complexes with optical spectroscopy

AU - Kofod, Nicolaj

AU - Henrichsen, Margrete Juel

AU - Sørensen, Thomas Just

PY - 2024

Y1 - 2024

N2 - The Tb(III) ion has the most intense luminescence of the trivalent lanthanide(III) ions. In contrast to Eu(III), where the two levels only include a single state, the high number of electronic states in the ground (7 F 6 ) and emitting ( 5 D4 ) levels makes detailed interpretations of the electronic structure—the crystal field— difficult. Here, luminescence emission and excitation spectra of Tb(III) complexes with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA, [Tb(DOTA)(H2O)]−), ethylenediaminetetraacetic acid (EDTA, [Tb(EDTA)(H2 O)3]−) and diethylenetriaminepentaacetic acid (DTPA, [Tb(DTPA)(H2O)]2−) as well as the Tb(III) aqua ion ([Tb(H2 O)9 ] 3+ ) were recorded at room temperature and in frozen solution. Using these data the electronic structure of the 5 D4 multiplets of Tb(III) was mapped by considering the transitions to the singly degenerate 7 F0 state. A detailed spectroscopic investigation was performed and it was found that the 5 D4 multiplet could accurately be described as a single band for [Tb(H2 O)9 ]3+ , [Tb(DOTA)(H 2O)]− and [Tb (EDTA)(H 2O)3 ]−. In contrast, for [Tb(DTPA)(H2 O)]2− two bands were needed. These results demonstrated the ability of describing the electronic structure of the emitting 5 D4 multiplet using emission spectra. This offers an avenue for investigating the relationship between molecular structure and luminescent properties in detailed photophysical studies of Tb(III) ion complexes.

AB - The Tb(III) ion has the most intense luminescence of the trivalent lanthanide(III) ions. In contrast to Eu(III), where the two levels only include a single state, the high number of electronic states in the ground (7 F 6 ) and emitting ( 5 D4 ) levels makes detailed interpretations of the electronic structure—the crystal field— difficult. Here, luminescence emission and excitation spectra of Tb(III) complexes with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA, [Tb(DOTA)(H2O)]−), ethylenediaminetetraacetic acid (EDTA, [Tb(EDTA)(H2 O)3]−) and diethylenetriaminepentaacetic acid (DTPA, [Tb(DTPA)(H2O)]2−) as well as the Tb(III) aqua ion ([Tb(H2 O)9 ] 3+ ) were recorded at room temperature and in frozen solution. Using these data the electronic structure of the 5 D4 multiplets of Tb(III) was mapped by considering the transitions to the singly degenerate 7 F0 state. A detailed spectroscopic investigation was performed and it was found that the 5 D4 multiplet could accurately be described as a single band for [Tb(H2 O)9 ]3+ , [Tb(DOTA)(H 2O)]− and [Tb (EDTA)(H 2O)3 ]−. In contrast, for [Tb(DTPA)(H2 O)]2− two bands were needed. These results demonstrated the ability of describing the electronic structure of the emitting 5 D4 multiplet using emission spectra. This offers an avenue for investigating the relationship between molecular structure and luminescent properties in detailed photophysical studies of Tb(III) ion complexes.

U2 - 10.1039/D3DT03657J

DO - 10.1039/D3DT03657J

M3 - Journal article

VL - 53

SP - 4461

EP - 4470

JO - Dalton Transactions (Online)

JF - Dalton Transactions (Online)

SN - 1477-9234

IS - 10

ER -