Fig. 3.

Dependence of the relaxivity r₁ and of the hydration number q on the Ca²⁺-to-complex ratio for Ln₂L¹. Squares correspond to the relaxivity values obtained from the relaxometric titration of Gd₂L¹ (298 K, 11.75 T). Filled triangles represent the hydration number obtained from luminescence lifetime studies on Eu₂L¹ and open triangles correspond to the molar fraction of the monohydrated species determined for Eu₂L¹ by UV–vis spectroscopy (ratio of the integrals of the absorption bands corresponding to monohydrated and nonhydrated complex; see text)