Table 1.
L | λmax(abs) [nm] L/ZnL2 | λmax(em) [nm] L/ZnL2 | ϕL [a] | ϕZnL2 [a] | Ka [m−2] |
---|---|---|---|---|---|
1 | (350, 495)/(361, 495) | 504/504 | 0.35 | 0.35 | 1 × 109 |
2 | 346/357 | 456/520 | 0.34 | 0.42 | 3 × 109 |
3 | (350, 495)/(365, 495) | 504/504 | 0.25 | 0.24 | 1 × 109 |
4 | (350, 495)/(359, 495) | 504/504 | 0.32 | 0.33 | 6 × 109 |
The ligand concentrations were kept at 1.0 µm. The excitation wavelengths are selected at the absorption maxima of the FRET donor bands of 1–4. Quinine bisulfate in 1 n H2SO4 solution was used as the standard. To ensure the saturation of zinc(II) in the measurements of ϕZnL2, the ratio of zinc(II)/L = 20:1.