Figure 2

Absorption spectra of 5 μM of complexes (a) 1, (c) 2 and (e) 3 in the presence of increasing concentrations of Cu²⁺ ion (1:1 ACN-Tris, pH 7.0). Absorbance of complexes (b) 1, (d) 2 and (f) 3 at 555 nm vs. [Cu²⁺]. Inset: linear plot of the change in absorbance of the system vs. [Cu²⁺].