Table 1.
Experimental stability constants 1 of Cu2+/3-hydroxy-4-pyridinone species obtained by different analytical techniques at I = 0.15 mol L−1 in NaCl(aq), T = 298.15 K and p = 0.1 MPa.
| logβpqr (logKpqr) | |||
|---|---|---|---|
| Species | Potentiometry | UV–Vis Spectrophotometry | Average Stability Constants 2 |
| CuH(L1)+ | 14.23 ± 0.04 3 (4.28) | - | - |
| Cu(L1)0(aq) | 9.76 ± 0.06 | - | - |
| CuH2(L2)2+ | 24.98 ± 0.02 3 (5.46) | 24.93 ± 0.05 3 (5.41) | 24.95 ± 0.07 4 (5.43) |
| CuH(L2)+ | 21.75 ± 0.03 (11.02) | 21.00 ± 0.04 (10.27) | 21.37 ± 0.30 (10.64) |
| Cu(L2)0(aq) | 15.10 ± 0.10 | 14.48 ± 0.105 | 14.79 ± 0.26 |
| CuH2(L3)2+ | 26.93 ± 0.02 3 (6.26) | - | - |
| Cu(L3)H+ | 22.84 ± 0.03 (11.85) | - | - |
| Cu(L3)0(aq) | 15.95 ± 0.03 | - | - |
| CuH2(L4)2+ | 25.65 ± 0.02 3 (5.21) | 25.66 ± 0.04 3 (5.22) | 25.65 ± 0.01 4 (5.21) |
| CuH(L4)+ | 21.63 ± 0.03 (10.53) | 21.78 ± 0.02 (10.68) | 21.70 ± 0.04 (10.60) |
| Cu(L4)0(aq) | 15.62 ± 0.07 | 15.62 ± 0.05 | 15.62 ± 0.06 |
| CuH(L5)2+ | 20.00 ± 0.03 3 (8.92) | 20.241 ± 0.006 3 (9.161) | 20.12 ± 0.09 4 (9.04) |
| Cu(L5)+ | 12.62 ± 0.06 | 12.67 ± 0.04 | 12.64 ± 0.04 |
1 logβpqr and logKpqr refer to Equations (2) and (1), respectively; 2 data obtained by an average of potentiometric and UV–Vis spectrophotometric data; 3 ±Std. Dev.; 4 errors on weighed data. Standard uncertainties: u(T) = 0.1 K; u(I) = 0.01 mol L−1.