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Yerly, F ; Dunand, FA ; Toth, E ; Figueirinha, A ; Kovacs, Z ; Sherry, AD ; Geraldes, CFGC ; Merbach, AE

Spectroscopic study of the hydration equilibria and water exchange dynamics of lanthanide(III) complexes of 1,7-bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

European Journal of Inorganic Chemistry (5) 1001-1006

par Administrateur - publié le

Abstract :

The hydration state of a series of [Ln(DO2A)(H2O)(n)](+) complexes in aqueous solution at pH = 6.4-7.0 was studied by measuring the lanthanide-induced O-17 shifts (LIS) of water [Ln includes elements from Ce to Yb ; DO2A = 1,7-bis(carboxymethyl)-1,4,7, 10-tetraazacyclododecane]. Their contact contribution, obtained from Reilley plots, indicated a decrease in the inner-sphere water coordination number of the [Ln(DO2A)(H2O)(n)]+ complexes from n = 3 (Ce-Eu), to n = 2 (Tb-Yb). A temperature-dependent UV/Vis absorption study of the 578-582 nm F-7(0) —> D-5(0) transition band of [Eu(DO2A)(H2O)(n)](+) in aqueous solution showed that this complex is present in an equilibrium between eight- and nine-coordinate species with n = 2 and n = 3, respectively.