Coordination equilibrium in an Ln(III) macrocyclic chelate modulated by a reversible interaction with a weakly donor substituent

Frank A. Dunand, Silvio Aime, Simonetta Geninatti Crich, Giovanni B. Giovenzana, André E. Merbach

Risultato della ricerca: Contributo su rivistaArticolo in rivistapeer review

Abstract

The introduction of a squaric acid moiety at the secondary nitrogen center of DO3A [DO3A = 1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane] yields the DO3ASQ ligand endowed with a potential octadenticity towards Ln(III) ions. On the basis of 17O NMR investigations on [Gd(DO3ASQ)(H 2O)], 13C NMR observations on [Lu(DO3ASQ)(H2O)] and UV spectra of [Eu(DO3ASQ)(H2O)], it is suggested that [Ln(DO3ASQ)(H2O)] complexes are present in solution as a mixture of two isomers differing in the coordination number of the Ln(III) ion, being 8 and 9, respectively. Only in the latter isomer is the squaric moiety coordinated to the Ln(III) ion. Interestingly, the two isomers display different exchange rates of the coordinated water molecule.

Lingua originaleInglese
pagine (da-a)87-92
Numero di pagine6
RivistaMagnetic Resonance in Chemistry
Volume40
Numero di pubblicazione1
DOI
Stato di pubblicazionePubblicato - 1 gen 2002

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