Table 2. Anion Binding Constants and Free Energy Values for Unscreened ( and ) and Screened ( and ) Models Determined from ¹H NMR Spectroscopy^a,b.

	unscreened model affinity		screened (Debye–Hückel) model affinity
anion	KX–U,0 (M–1)	KX–U,0 (kJ·mol–1)	KX–S,0 (M–1)c	(kJ·mol–1)
F–	104 ± 14d	–11.49 ± 0.32	61 ± 4	–10.18 ± 0.16
Cl–	290 ± 20e	–14.06 ± 0.17	452 ± 4	–15.15 ± 0.02
Br–	1860 ± 237d	–18.64 ± 0.33	2890 ± 65	–19.74 ± 0.06
I–	12 800 ± 1450d	–23.43 ± 0.29	19 900 ± 1700	–24.52 ± 0.20

^a[Host 1] = at 0.4 mM concentration in unbuffered D₂O

^bThe pD values of the solutions were uncorrected.

^cResults correspond to a host Born radius of 6.5 Å. Values correspond to Born radii of 5.5 and 7.5 Å were as follows: F^–, 58 and 64, Cl^–, 446 and 457, Br^–, 2880 and 2890, and I^–, 19 900 and 19 800 M^–1.

^d values for F^–, Br^–, and I^– obtained by competitive complexation model (eq 14a) using = 290 M^–1.

^e value obtained by fitting to the standard 1:1 model, accounting for 4 equiv of Cl^– and floating the initial point.