Table 3. Anion Association Constants for Receptors 1 and 2 (K_1:1^A, M^–1, Anion Binding Mode A) and 16 (K_1:1, M^–1) in the Presence of 1 equiv of K⁺.

	1			2			16
anion	K1:1A a	αb	Ac (%)	K1:1A a	αb	Ac (%)	K1:1A a	αb
Cl–	9500 ± 200	2.6	63	5300 ± 200	2.2	57	34200 ± 600	12.7
Br–	21200 ± 1300	4.1	83	6100 ± 200	2.1	73	54000 ± 4600	13.5
I–	34200 ± 2700	7.4	>95	17800 ± 600	5.2	>90	43100 ± 3700	13.5

^aSolvent: 3:1 CDCl₃:CD₃CN at 298 K. Values reported as the mean and the standard error of the mean from independently repeated experiments.

^bBinding enhancement factors in the presence of K⁺.

^cContributions of anion binding mode A to overall 1:1 binding.