Table 1.

Protonation constants of TRAP⁶⁻, NOTA³⁻, and Bha⁻ ligands (25°C).

	I	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$K_6^{\text{H}}$	Σlog$K_{\text{i}}^{\text{Hf}}$
TRAP6−	0.15 M NaNO3	11.60(2)	5.39(2)	4.42(2)	4.19(3)	3.46(3)	1.60(2)	18.59 g
	0.15 M NaCla	11.74	5.46	4.80	4.16	3.49	1.50	18.70 g
	0.1 M Me4NCl b	11.48	5.44	4.84	4.23	3.45	1.66	18.58 g
NOTA3−	0.15 M NaNO3	11.94(2)	5.71(3)	3.14(3)	1.60(2)	–	–	22.39
	0.15 M NaCla	12.16	5.75	3.18	1.90	–	–	22.99
	0.1 M KClc	11.98	5.65	3.18	–	–	–	–
	0.1 M Me4NCld	13.17	5.74	3.22	1.96	–	–	24.09
Bha−	0.15 M NaNO3	8.53(3)	–	–	–	–	–	–
	0.2 M KCle	8.69	–	–	–	–	–	–

^aRef. (Baranyai et al., 2015);

^bRef. (Notni et al., 2010);

^cRef. (Clarke and Martell, 1991);

^dRef. (Drahos et al., 2011);

^eRef. (Farkas et al., 1998);

^fTotal ligand basicity (Σlog$k_i^H$) characterizes the sum of basicity of donor atoms;

^gThe protonation constants of the acetate pendants (log$k_3^H$, log$k_4^H$ and log$k_5^H$) of TRAP⁶⁻ were not considered in the calculation of Σlog$k_i^H$ values.