Figure 3.

(a) Steady-state UV–Vis absorption spectra of complexes 1, 2, 3, and the free ligands L1, L2, and H₃bib in CH₂Cl₂ at 20 °C. (b) UV–Vis absorption changes of 1 on electrochemical (ligand-centered) reduction at −1.0 V vs Ag/AgCl in deaerated CH₂Cl₂ at 20 °C with 0.1 M TBAPF₆ as a supporting electrolyte. The arrows mark the spectral evolution as a function of the time during which the potential was applied. (c) UV–Vis transient absorption spectra of 0.5 mM 1 in aerated CH₃CN at 20 °C, recorded at different delay times as indicated in the insets following excitation at 380 nm. Upper part: Spectra recorded at short delay times, in which changes of excited-state absorption (ESA) are most apparent (arrow pointing downwards). Lower part: spectra recorded at longer delay times, in which changes in ground-state bleaching (GSB) are most apparent (arrow pointing upward). (d) UV–Vis transient absorption spectra of 0.5 mM 1 in aerated CH₂Cl₂ at 20 °C, recorded at different delay times as indicated in the insets following excitation at 380 nm.