Table 2. Ligand Protonation Constants and Stability Constants of the Cu(II) Complexes Determined Using Potentiometric and Spectrophotometric Titrations (1 M NaCl, 25 °C).

	CHXDEDPA2–	CpDEDPA2–	CBuDEDPA2–	DEDPA2–c
I	1 M NaCl	1 M NaCl	1 M NaCl	1 M NaCl
log K1H	9.41(1)/9.23a/9.13b	9.05(1)	8.95(1)	9.00c/8.69b
log K2H	6.45(1)/6.47a/6.44b	6.51(2)	6.87(1)	6.30c/6.18b
log K3H	3.35(2)/2.99a/3.25b	3.28(3)	3.32(2)	3.06c/3.08b
log K4H	2.48(2)/2.40a/2.40b	2.51(4)	2.52(3)	2.59c/2.33b
Σ log KiH (i = 1–4)	21.69/21.09a/21.22b	22.18	20.19	20.95c
log KCuL	25.11(1)	22.18(1)	20.19(1)	19.16d
pCue	24.0	21.4	19.5	18.5

^aData in 0.15 M NaCl from ref (27).

^bData in 0.1 M (Me₄N)(NO₃) from ref (25).

^cData in 0.15 M NaCl from ref (26).

^dData in 0.15 M NaCl from ref (28).

^eDefined as–log [Cu(II)]_free, for [L]_tot = 10 μM and [Cu(II)]_tot = 1 μM.