Lanthanide complexes based on a diazapyridinophane platform containing picolinate pendants. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Inorganic Chemistry Année : 2012

Lanthanide complexes based on a diazapyridinophane platform containing picolinate pendants.

Adrián Roca-Sabio
  • Fonction : Auteur
Célia S Bonnet
Marta Mato-Iglesias
  • Fonction : Auteur
David Esteban-Gómez
Éva Tóth
Teresa Rodríguez-Blas
  • Fonction : Auteur
Carlos Platas-Iglesias

Résumé

A new macrocyclic ligand, N,N'-bis[(6-carboxy-2-pyridyl)methyl]-2,11-diaza[3.3](2,6)pyridinophane (H(2)BPDPA), was prepared, and its coordination properties toward the Ln(III) ions were investigated. The hydration numbers (q) obtained from luminescence lifetime measurements in aqueous solution of the Eu(III) and Tb(III) complexes indicate that they contain one inner-sphere water molecule. The structure of the complexes in solution has been investigated by (1)H and (13)C NMR spectroscopy, as well as by theoretical calculations performed at the density functional theory (B3LYP) level. The minimum-energy conformation calculated for the Yb(III) complex is in excellent agreement with the experimental structure in solution, as demonstrated by analysis of the Yb(III)-induced paramagnetic (1)H shifts. Nuclear magnetic relaxation dispersion (NMRD) profiles and (17)O NMR measurements recorded on solutions of the Gd(III) complex were used to determine the parameters governing the relaxivity. The results show that this system is endowed with a relatively fast water-exchange rate k(ex)(298) = 63 × 10(6) s(-1). Thermodynamic stability constants were determined by pH-potentiometric titration at 25 °C in 0.1 M KCl. The stability constants, which fall within the range logK(LnL) = 12.5-14.2, point to a relatively low stability of the complexes primarily as a consequence of the low basicity of the ligand.
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Dates et versions

hal-00817354 , version 1 (24-04-2013)

Identifiants

Citer

Adrián Roca-Sabio, Célia S Bonnet, Marta Mato-Iglesias, David Esteban-Gómez, Éva Tóth, et al.. Lanthanide complexes based on a diazapyridinophane platform containing picolinate pendants.. Inorganic Chemistry, 2012, 51 (20), pp.10893-10903. ⟨10.1021/ic301369z⟩. ⟨hal-00817354⟩
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