Figure 2
UV–vis spectra recorded in toluene for (a) (1E), (b) (2E), (c) (3E) and (d) (4E) after 10 min irradiation. Green broken lines indicate UV–vis spectra recorded in toluene before irradiation; black dotted lines indicate the UV–vis spectra recordered for samples after irradiation in toluene for 10 min; orange solid lines indicate UV–vis spectra obtained for samples irradiated in the crystalline powder form for 10 min and then dissolving in toluene. |