Synthesis and Complex Formation of Rhodamine-Substituted Spirobenzopyranindolines

Abstract

Novel spirobenzopyranindolines containing a rhodamine fragment linked to a benzopyran fragment with an aminomethylene spacer were synthesized by the reaction of 7-hydroxy-6-formyl-substituted spiropyrans and rhodamine B hydrazide. The synthesized spiropyrans in toluene and acetone are present in the spiropyran‒spirolactam form. The 5-methyl-substituted was the only to exhibit photochromism. Adding Zn(II), Ni(II), Co(II), and Cd(II) perchlorates to the spiropyran solutions leads to intense coloration due to complex formation.