Fig. 1. Redox properties of ligands.

a One-electron redox process on the studied R-pbpyCl ligands (R-pbpy⁺= 1-(4-R-phenyl)−4,4’-bipyridinium); b Cyclic voltammetry of CH₃-pbpy⁺ (1) showing the reversible reduction of the bipyridinium unit (see Supplementary Fig. 6 for R = Br (2), COOCH₃ (3) and NO₂ (4)). [C] = 10⁻⁴ M in 0.1 M TBAP/CH₃CN; reference: Ag+|Ag electrode ([Ag⁺]=10⁻² M in CH₃CN); scan rate: 100 mV·s⁻¹.