Research Article
Synthesis of Novel Iono- and Photochromic Spiropyrans Derived from 6,7-Dihydroxy-8-Formyl-4-Methyl-2H-Chromene-2-One
Figure 3
(a) NMR spectra of (4a) in dark conditions in CCN-nitrobenzene- ( v/v) and (b) in presence of Mg(Cl after 10 minutes; (c) 1 hour ().