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2005-01-01 - Article/Dans un journal avec peer-review - Anglais - 14 page(s)

Vander Elst Luce , Sessoye A., Laurent Sophie , Muller Robert , "Can the theoretical fitting of the proton-nuclear-magnetic-relaxation-dispersion (proton NMRD) curves of paramagnetic complexes be improved by independent measurement of their self-diffusion coefficients?" in Helvetica Chimica Acta, 88, 3, 574-587

  • Edition : Verlag Helvetica Chimica Acta, Basel (Switzerland)
  • Codes CREF : Physico-chimie générale (DI1320), Résonance magnétique nucléaire (biophysique) (DI131B)
  • Unités de recherche UMONS : Chimie générale, organique et biomédicale (M108)
Texte intégral :

Abstract(s) :

(Anglais) The self-diffusion (D,) coefficients of various lanthanum(III) diamagnetic analogues of open-chain and macrocyclic complexes of gadolinium used as MRI contrast agents were determined in dilute aqueous solutions (3-31 mm) by pulsed-field-gradient (PFG) high-resolution H-1-NMR spectroscopy. The self-diffusion coefficient of H2O (D-w) was obtained for the same samples to derive the relative diffusion constant, a parameter involved in the outersphere paramagnetic-relaxation mechanism. The results agree with an averaged relative diffusion constant of 2.5(+/- 0.1) x 10(-9) and of 3.3(+/- 0.1) x 10(-9) m(2) s(-1) at 25 and 37 degrees, respectively, for 'small' contrast agents (M-r 500- 750 g/mol), and with the value of bulk H2O (2.2 x 10(-9) and 2.9 x 10(-9) m(2) s(-1) at 25 degrees and at 37 degrees, respectively) for larger complexes. The use of the measured values of D-c for the theoretical fitting of proton NMRD curves of gadolinium complexes shows that the rotational correlation times (tau(R)) are very close to those already reported. However, differences in the electronic relaxation time (tau(SO)) at very low field and in the correlation time (tau(V)) related to electronic relaxation were found.

Identifiants :
  • ISSN : 0018-019X