Table 1.

Protonation constants of the hexa-, hepta- and octadentate ligands (I = 0.15 M NaCl, 25 °C).

	log $K_1^{\text{H}}$	log $K_2^{\text{H}}$	log $K_3^{\text{H}}$	log $K_4^{\text{H}}$	log $K_5^{\text{H}}$	log $K_6^{\text{H}}$	Σ log$K_2^{\text{H}}$
DO3A	10.07 (5)	8.93 (6)	4.43 (9)	4.11 (7)	1.88 (7)	–	19.00
DO3AMH	9.40 (5)	6.28 (8)	–	–	–	–	15.68
DO3P	12.55 (2)	11.37 (1)	8.57 (2)	7.02(2)	5.36 (2)	1.84 (2)	23.92
ODO3A	8.74 (2)	7.58 (2)	3.99 (3)	2.39(3)	–	–	16.32
PCTA	9.97 (3)	6.73 (5)	3.22 (6)	1.40 (9)	–	–	16.70
PC3AMH	8.76 (3)	4.10 (4)	–	–	–	–	12.86
PC3AMGly	8.85 (1)	4.55 (1)	3.81 (1)	3.21 (1)	2.80 (1)	1.38 (1)	13.40
PC3AMPip	8.74 (1)	5.77 (2)	1.42 (9)	–	–	–	14.51
DOTA[c]	11.41	9.83	4.38	4.63	1.92	1.58	21.24
DOTMA[b]	11.72	9.06	4.74	5.59	1.92	–	20.78
DOTAM	7.31 (1)	6.07 (1)	–	–	–	–	13.38
DOTP	13.6 (2)[a]	12.23 (3)	8.63 (5)	7.45 (4)	5.84 (5)	5.02 (5)	25.83
trans-DO2A[d]	11.69	9.75	3.97	2.68	–	–	21.44
cis-DO2A[d]	11.44	9.51	4.14	1.55	–	–	20.95
cis-DO2AMMe2, [e]	10.14	8.38	–	–	–	–	18.52
cis-Bz2DO2AMMe2, [f]	11.11	8.22	–	–	–	–	19.33
cis-DO2AMBz2, [f]	9.62	6.90	–	–	–	–	16.52

^[a]1H- and ³¹P-NMR;

^[b]I = 0.1 M KCl (Aime et al., 2011);

^[c]0.1 M KCl (Takács et al., 2014);

^[d]Garda et al. (2016);

^[e]I = 0.1 M KCl (Forgács et al., 2016);

^[f]I = 0.1 M KCl (Forgács et al., 2017).