Table 4. Logarithmic Binding Constants (log K^a) for Complexes between Receptors and Diverse Anions^b Obtained by ¹H NMR, in CD₃CN/DMSO-d₆ 9:1 (v/v) at 298 K^e.

system	log K	OAc–	αc	OBz–	αc	HSO4–	αc	NO3–
R1	log K11	3.45	0.54	2.75	1.15	1.66		1.48
	log K 12	2.58		2.21
	log β	6.03		4.97
R2	log K 11	3.37	1.00	2.87	1.26	2.90	0.15	1.61
	log K12	2.77		2.37		1.48
	log β	6.14		5.24		4.38
R3	log K11	3.48	0.45	–d		2.06		1.66
	log K12	2.53
	log β	6.01

^aError less than 10%.

^bAnions were added as their TBA salts.

^cParameter α is used to quantify the extent of cooperativity and is defined as α = 4K₂/K₁.^28,29

^dNot determined due to precipitation.

^eDeprotonation of receptors was observed with H₂PO₄^–, F^–, and PPi^3–.