Synthesis of Novel Iono- and Photochromic Spiropyrans Derived from 6,7-Dihydroxy-8-Formyl-4-Methyl-2H-Chromene-2-One

Figure 1

Absorption spectra of (4a) in acetonitrile solution before irradiation (1); after 15 seconds (2); 45 seconds (3); 90 seconds (4); 150 seconds (5); 180 seconds (6); 8 minutes (7); 16 minutes (8); 26 minutes (9) of irradiation (𝜆_irr= 365 nm, C=2.5⋅10⁻⁵ M).