Responsive, di-metallic lanthanide complexes of a piperazine-bridged bis-macrocyclic ligand: Modulation of visible luminescence and proton relaxivity

M. Andrews, A.J. Amoroso, L.P. Harding, S.J.A. Pope

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The synthesis of a new functionalised bis-macrocyclic ligand (L1) is described together with the corresponding LnIII complexes, Ln2-L1 (Ln = GdIII, EuIII). Phosphorescence measurements on Gd2-L1 at 77 K allowed the ligand-centred triplet state (3π–π*) to be estimated at ca. 28500 cm−1. Steady state and time-resolved measurements confirmed emission from the f-centred excited state (5D0) for Eu2-L1. 1H NMRD profiles revealed the longitudinal proton relaxivity (r1) of Gd2-L1 to be 8.3 mM−1s−1(30 MHz, 25 °C). The interaction of CuII and HgII with the lanthanide complexes was probed using luminescence and relaxivity measurements. Addition of CuII (10 eq.) resulted in quenching of the EuIII emission, but no increase in r1 of the GdIII dimer. Addition of HgII (10 eq.) caused changes to the hypersensitive emission bands of EuIII together with an increase in r1 of Gd2-L1 to be 10.3 mM−1s−1(30 MHz, 25 °C) suggesting a net increase in hydration at the GdIII centres.
LanguageEnglish
Pages3407-3411
Number of pages5
JournalDalton Transactions
Volume39
Issue number14
DOIs
Publication statusPublished - Feb 2010

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Lanthanoid Series Elements
Protons
Luminescence
Modulation
Ligands
Phosphorescence
Time measurement
Excited states
Hydration
Dimers
Quenching
piperazine

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title = "Responsive, di-metallic lanthanide complexes of a piperazine-bridged bis-macrocyclic ligand: Modulation of visible luminescence and proton relaxivity",
abstract = "The synthesis of a new functionalised bis-macrocyclic ligand (L1) is described together with the corresponding LnIII complexes, Ln2-L1 (Ln = GdIII, EuIII). Phosphorescence measurements on Gd2-L1 at 77 K allowed the ligand-centred triplet state (3π–π*) to be estimated at ca. 28500 cm−1. Steady state and time-resolved measurements confirmed emission from the f-centred excited state (5D0) for Eu2-L1. 1H NMRD profiles revealed the longitudinal proton relaxivity (r1) of Gd2-L1 to be 8.3 mM−1s−1(30 MHz, 25 °C). The interaction of CuII and HgII with the lanthanide complexes was probed using luminescence and relaxivity measurements. Addition of CuII (10 eq.) resulted in quenching of the EuIII emission, but no increase in r1 of the GdIII dimer. Addition of HgII (10 eq.) caused changes to the hypersensitive emission bands of EuIII together with an increase in r1 of Gd2-L1 to be 10.3 mM−1s−1(30 MHz, 25 °C) suggesting a net increase in hydration at the GdIII centres.",
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Responsive, di-metallic lanthanide complexes of a piperazine-bridged bis-macrocyclic ligand: Modulation of visible luminescence and proton relaxivity. / Andrews, M.; Amoroso, A.J.; Harding, L.P.; Pope, S.J.A.

In: Dalton Transactions, Vol. 39, No. 14, 02.2010, p. 3407-3411.

Research output: Contribution to journalArticle

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AB - The synthesis of a new functionalised bis-macrocyclic ligand (L1) is described together with the corresponding LnIII complexes, Ln2-L1 (Ln = GdIII, EuIII). Phosphorescence measurements on Gd2-L1 at 77 K allowed the ligand-centred triplet state (3π–π*) to be estimated at ca. 28500 cm−1. Steady state and time-resolved measurements confirmed emission from the f-centred excited state (5D0) for Eu2-L1. 1H NMRD profiles revealed the longitudinal proton relaxivity (r1) of Gd2-L1 to be 8.3 mM−1s−1(30 MHz, 25 °C). The interaction of CuII and HgII with the lanthanide complexes was probed using luminescence and relaxivity measurements. Addition of CuII (10 eq.) resulted in quenching of the EuIII emission, but no increase in r1 of the GdIII dimer. Addition of HgII (10 eq.) caused changes to the hypersensitive emission bands of EuIII together with an increase in r1 of Gd2-L1 to be 10.3 mM−1s−1(30 MHz, 25 °C) suggesting a net increase in hydration at the GdIII centres.

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