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Surprising Complexity of the [Gd(AAZTA)(H(2)O)(2)](−) Chelate Revealed by NMR in the Frequency and Time Domains

[Image: see text] Typically, Ln(III) complexes are isostructural along the series, which enables studying one particular metal chelate to derive the structural features of the others. This is not the case for [Ln(AAZTA)(H(2)O)(x)](−) (x = 1, 2) systems, where structural variations along the series c...

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Autores principales: Lalli, Daniela, Carniato, Fabio, Tei, Lorenzo, Platas-Iglesias, Carlos, Botta, Mauro
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8753608/
https://www.ncbi.nlm.nih.gov/pubmed/34890182
http://dx.doi.org/10.1021/acs.inorgchem.1c03194
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author Lalli, Daniela
Carniato, Fabio
Tei, Lorenzo
Platas-Iglesias, Carlos
Botta, Mauro
author_facet Lalli, Daniela
Carniato, Fabio
Tei, Lorenzo
Platas-Iglesias, Carlos
Botta, Mauro
author_sort Lalli, Daniela
collection PubMed
description [Image: see text] Typically, Ln(III) complexes are isostructural along the series, which enables studying one particular metal chelate to derive the structural features of the others. This is not the case for [Ln(AAZTA)(H(2)O)(x)](−) (x = 1, 2) systems, where structural variations along the series cause changes in the hydration number of the different metal complexes, and in particular the loss of one of the two metal-coordinated water molecules between Ho and Er. Herein, we present a (1)H field-cycling relaxometry and (17)O NMR study that enables accessing the different exchange dynamics processes involving the two water molecules bound to the metal center in the [Gd(AAZTA)(H(2)O)(2)](−) complex. The resulting picture shows one Gd-bound water molecule with an exchange rate ∼6 times faster than that of the other, due to a longer metal–water distance, in accordance with density functional theory (DFT) calculations. The substitution of the more labile water molecule with a fluoride anion in a diamagnetic-isostructural analogue of the Gd-complex, [Y(AAZTA)(H(2)O)(2)](−), allows us to follow the chemical exchange process by high-resolution NMR and to describe its thermodynamic behavior. Taken together, the variety of tools offered by NMR (including high-resolution (1)H, (19)F NMR as a function of temperature, (1)H longitudinal relaxation rates vs B(0), and (17)O transverse relaxation rates vs T) provides a complete description of the structure and exchange dynamics of these Ln-complexes along the series.
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spelling pubmed-87536082022-01-12 Surprising Complexity of the [Gd(AAZTA)(H(2)O)(2)](−) Chelate Revealed by NMR in the Frequency and Time Domains Lalli, Daniela Carniato, Fabio Tei, Lorenzo Platas-Iglesias, Carlos Botta, Mauro Inorg Chem [Image: see text] Typically, Ln(III) complexes are isostructural along the series, which enables studying one particular metal chelate to derive the structural features of the others. This is not the case for [Ln(AAZTA)(H(2)O)(x)](−) (x = 1, 2) systems, where structural variations along the series cause changes in the hydration number of the different metal complexes, and in particular the loss of one of the two metal-coordinated water molecules between Ho and Er. Herein, we present a (1)H field-cycling relaxometry and (17)O NMR study that enables accessing the different exchange dynamics processes involving the two water molecules bound to the metal center in the [Gd(AAZTA)(H(2)O)(2)](−) complex. The resulting picture shows one Gd-bound water molecule with an exchange rate ∼6 times faster than that of the other, due to a longer metal–water distance, in accordance with density functional theory (DFT) calculations. The substitution of the more labile water molecule with a fluoride anion in a diamagnetic-isostructural analogue of the Gd-complex, [Y(AAZTA)(H(2)O)(2)](−), allows us to follow the chemical exchange process by high-resolution NMR and to describe its thermodynamic behavior. Taken together, the variety of tools offered by NMR (including high-resolution (1)H, (19)F NMR as a function of temperature, (1)H longitudinal relaxation rates vs B(0), and (17)O transverse relaxation rates vs T) provides a complete description of the structure and exchange dynamics of these Ln-complexes along the series. American Chemical Society 2021-12-10 2022-01-10 /pmc/articles/PMC8753608/ /pubmed/34890182 http://dx.doi.org/10.1021/acs.inorgchem.1c03194 Text en © 2021 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Lalli, Daniela
Carniato, Fabio
Tei, Lorenzo
Platas-Iglesias, Carlos
Botta, Mauro
Surprising Complexity of the [Gd(AAZTA)(H(2)O)(2)](−) Chelate Revealed by NMR in the Frequency and Time Domains
title Surprising Complexity of the [Gd(AAZTA)(H(2)O)(2)](−) Chelate Revealed by NMR in the Frequency and Time Domains
title_full Surprising Complexity of the [Gd(AAZTA)(H(2)O)(2)](−) Chelate Revealed by NMR in the Frequency and Time Domains
title_fullStr Surprising Complexity of the [Gd(AAZTA)(H(2)O)(2)](−) Chelate Revealed by NMR in the Frequency and Time Domains
title_full_unstemmed Surprising Complexity of the [Gd(AAZTA)(H(2)O)(2)](−) Chelate Revealed by NMR in the Frequency and Time Domains
title_short Surprising Complexity of the [Gd(AAZTA)(H(2)O)(2)](−) Chelate Revealed by NMR in the Frequency and Time Domains
title_sort surprising complexity of the [gd(aazta)(h(2)o)(2)](−) chelate revealed by nmr in the frequency and time domains
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8753608/
https://www.ncbi.nlm.nih.gov/pubmed/34890182
http://dx.doi.org/10.1021/acs.inorgchem.1c03194
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