Table 3. Observed (K_obs^U,0) and Predicted (K_pred) Binding Constants for the Binding of Halide Guests to 1^a.

	KobsU,0 (M–1)b			KpredU,0 (M–1)c
guest	10 mM, pH = 7.3d	23.8 mM, pH = 3.0e	10 mM, pH = 3.0f	10 mM, pH = 7.3d	23.8 mM, pH = 3.0e	10 mM, pH = 3.0f
F–	—g	—g	—g	35 ± 7	40 ± 8	62 ± 12
Cl–	135 ± 3	143 ± 8	166 ± 6	120 ± 20	130 ± 20	180 ± 20
Br–	738 ± 27	862 ± 48	1020 ± 51	630 ± 130	740 ± 150	1110 ± 200
I–	5430 ± 324	6000 ± 489	7410 ± 314	4325 ± 810	5110 ± 810	7850 ± 1240

^a[Host 1] = 0.4 mM.

^bAverage values based on at least three determinations.

^cErrors were propagated from the relative errors of each of the anions (SI Section 4.A.f).

^d10 mM sodium phosphate buffer, pH 7.3 (I = 21.0 mM).

^e23.8 mM sodium phosphate buffer, pH 3.0 (I = 21.0 mM).

^f10 mM sodium phosphate buffer, pH = 3.0 (I = 8.8 mM).

^gThe measured binding was too weak to determine accurately.