Table 5.

Proton-assisted dissociation rates for two [Ln{DOTA-(MeAm)₄}]³⁺ complexes.

Ln3+	k	DOTA	DOTA-(MeAm)4	DOTA-(gly)4a
Ce3+	k0 S−1	not observed	(1.1 ± 0.1) ×10− 5	not studied
	k1 M−1 S−1	8 ×10−4b	(2.6 ±0.1) ×10− 5	not studied
Eu3+	k0 S− 1	not observedc	(1.5 ± 0.2) ×10− 7	7.3 × 10− 7
	k1 M− 1 S−1	1.4 ×10−5d	(5.6 ± 0.2) ×10− 7	8.1 × 10− 6

^aRef.[11]

^bRef.[8], second-order dependence on H⁺ ion concentration with a third-order rate constant of 2.0 ×10^{− 3} M^{− 2} S^{− 1} was also observed.

^cFor [Gd(DOTA)] ⁻, k₀ = 5 ×10^{− 8} S^{− 1} and k₁ = 5 ×10^{− 6} M^{− 1} S^{− 1} from ref.[10]

^dRef.[9]