Figure 3.

Properties of substituted PIO derivatives. (A) Normalized UV/Vis spectra of substituted PIO derivatives. (B) Hammett plots for the thermal back‐isomerisation step kinetics, obtained using the σ_p values for the phenyl‐substituted PIO derivatives in MeCN and MeOH (measured at 20 °C) compared to the computed values obtained at the M06‐2X/def2‐SVP level of theory in vacuo. For the latter, a better correlation was obtained employing the σ_p ⁺ value for OMe. (C) Heatmap of the ns transient absorption spectra of iBu‐PIO. In the inset, fit of the decay of the absorption maximum (395 nm) of the transient signal (red line) as obtained from a global analysis of the transient spectra.