Table 1.

Halide anion association constants and calculated binding enhancement factors for phenyl and pefluorophenyl appended ChB, XB and HB acyclic anion receptor systems.

	Anion association constants K a [M−1][a]						Binding enhancement factors α=(K a PFP/K a Ph)
Anion[b]	1⋅ChBPFP [c]	1⋅ChBPh [a]	1⋅XBPFP [d]	1⋅XBPh [d]	1⋅HBPFP [c]	1⋅HBPh [c]	ChB	XB	HB
Cl−	18 500[e]	590	2920	416	386	394	32±4	7.0±0.2	0.86±0.06
Br−	4620	304	4600	1060	116	191	15±0.5	4.4±0.3	0.76±0.03
I−	1230	234	5230	1450	37	49	5.2±0.4	3.6±0.3	0.86±0.05

[a] Association constants determined by Bindfit analysis of internal pyridine proton signal, errors <5 % unless otherwise specified. [b] Anions added as their tetrabutylammonium salts. [c] Conducted in [D₆]acetone. [d] Conducted in 2.5 % D₂O‐[D₆]acetone (v/v). [e] Error <13 %.