Synthesis and studies of photochromic properties of spirobenzopyran carboxy derivatives and their model compounds as potential markers

A number of photochromic markers, viz., spirobenzopyrans containing one or two active carboxy groups attached directly or through a spacer, as well as their model derivatives, were synthesized. The obtained compounds were characterized by instrumental methods of analysis. Spectrokinetic methods were used to study the behavior of the spirobenzopyran markers and the model derivatives in solutions in EtOH and toluene.