Synthesis and spectrokinetic studies of a new family of photochromic 2H-chromenes (=2H-1-benzopyrans): Dimethyl 6-aryl-2,2-dimethyl-2H-chromene-7,8-dicarboxylates

A series of dimethyl 6-aryl-2,2dimethyl-2N-chromene-7,8-dicarboxylates were synthesized, and the photochromic properties of this new family of dimethy l-2H-chromenes were studied under continuous irradiation. The presence of t he methoxycarbonyl groups was shown to stabilize the colored forms. This st abilization depended on the solvent, and in two cases the formation of long -lived opened forms was observed. Under irradiation with a mercury lamp, th is family of 2H-chromenes showed a strong resistance: to photodegradation.