Ground-state absorption and fluorescence spectra were recorded on a Beckman DU640 spectrophotometer and a Jobin Yvon FluoroMax 2 fluorescence spectrophotometer, respectively. Fluorescence lifetimes were measured using a pulsed LED emitting at 457 nm together with a pulsed diode controller (PDL-800-B, Picoquant) operating at 10 MHz for excitation source. The detection was made using a fast photomulplier (H5783P-04, Hamamatsu) and a single photon counting setup (Fluotime 100 and Timeharp 200, Picoquant). The response function was lower than 0.7 ns and a classical procedure of iterative deconvolution was applied. All the fluorescence experiments were performed in acetonitrile under argon bubbling.