Interfacial binding constants K_Ox, K_Red (M⁻¹), BEF (K_Ox/K_Red) and BEF ratios with various anions and 2.XB/HB_SAM in ACN/H₂O 99 : 1 (+100 μM H⁺) as determined by electrochemical titrations. All isotherms were fit to eqn (2) to obtain absolute binding constants (Fig. 5). Mathematical errors from the fitting are generally <20% (see ESI for further details).

	2.XBSAM			2.HBSAM			Ratio XB/HB
	K Ox	K Red	BEF	K Ox	K Red	BEF
Cl−	2280	3	760	1960	4	489	1.55
Br−	1710	82	20.9	1380	53	26.0	0.80
HSO4−	1590	20	79.5	3920	51	76.9	1.03
H2PO4−	≈0.9 × 106	≈1000	≈900	≈1.5 × 106	≈1000	≈1500	≈0.6
NO3−	138	11	12.5	281	36	7.81	1.60