TY - JOUR
T1 - Interaction of [Ln(DO2A)(H2O)2-3]+ and [Ln(DO2P)(H2O)2-3]- with phosphate, acetate and fluoride anions in aqueous solution
AU - Kimpe, K.
AU - D'Olieslager, W.
AU - Görller-Walrand, C.
AU - Figueirinha, A.
AU - Kovács, Z.
AU - Geraldes, C. F G C
N1 - Funding Information:
Support of this research by a grant from Fundação da Ciência e Tecnologia, Portugal (PRAXIS 2/2.1/SAU/1194/96) is gratefully acknowledged. This work was carried out in the framework of COST D18 Action of the E.U. K. Kimpe wishes to thank the K.U. Leuven for financial support.
PY - 2001/7/12
Y1 - 2001/7/12
N2 - Mixed complexation of the lanthanide(III) chelates of the 1,7-disubstituted tetraazacyclododecane macrocycles DO2A and DO2P with phosphate, acetate and fluoride anions was studied in aqueous solutions using high resolution 1H and 31P NMR spectroscopy. The [La(DO2A)(H2O)2-3]+ and [Ce(DO2A)(H2O)2-3]+ chelates readily decompose in aqueous solutions containing phosphate anions. [Nd(DO2A)(H2O)2-3]+ and [Eu(DO2A)(H2O)2-3]+ chelates remain stable in an acetate environment. Association constants for the 1:1 adduct were obtained via 1H NMR titrations. In a fluoride environment, [La(DO2A)(H2O)2-3]+ was found to be unstable, in contrast to [Eu(DO2A)(H2O)2-3]+, for which the association constant for the 1:1 adduct was calculated. Chelate formation, as well as mixed complexation with fluoride and phosphate was studied for [Eu(DO2P)(H2O)2-3]-. The 31P chemical shifts of [Eu(DO2P)(H2O)2-3]- indicate that the DO2P macrocycle forms an 'in-cage' complex with binding through all four nitrogens. The [Eu(DO2P)(H2O)2-3]- chelate gradually decomposes in a phosphate environment, but remains stable in an fluoride environment.
AB - Mixed complexation of the lanthanide(III) chelates of the 1,7-disubstituted tetraazacyclododecane macrocycles DO2A and DO2P with phosphate, acetate and fluoride anions was studied in aqueous solutions using high resolution 1H and 31P NMR spectroscopy. The [La(DO2A)(H2O)2-3]+ and [Ce(DO2A)(H2O)2-3]+ chelates readily decompose in aqueous solutions containing phosphate anions. [Nd(DO2A)(H2O)2-3]+ and [Eu(DO2A)(H2O)2-3]+ chelates remain stable in an acetate environment. Association constants for the 1:1 adduct were obtained via 1H NMR titrations. In a fluoride environment, [La(DO2A)(H2O)2-3]+ was found to be unstable, in contrast to [Eu(DO2A)(H2O)2-3]+, for which the association constant for the 1:1 adduct was calculated. Chelate formation, as well as mixed complexation with fluoride and phosphate was studied for [Eu(DO2P)(H2O)2-3]-. The 31P chemical shifts of [Eu(DO2P)(H2O)2-3]- indicate that the DO2P macrocycle forms an 'in-cage' complex with binding through all four nitrogens. The [Eu(DO2P)(H2O)2-3]- chelate gradually decomposes in a phosphate environment, but remains stable in an fluoride environment.
KW - Lanthanides
KW - MRI contrast agents
KW - Nuclear resonances
KW - Rare earths
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U2 - 10.1016/S0925-8388(01)01154-9
DO - 10.1016/S0925-8388(01)01154-9
M3 - Conference article
AN - SCOPUS:18744436633
SN - 0925-8388
VL - 323-324
SP - 828
EP - 832
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
T2 - 4th International Conference on f-Elements
Y2 - 17 September 2000 through 21 September 2000
ER -