One-step synthesis of novel photochemically bifunctional compounds of the spiropyran class

The one-step reaction of 5-amino-1,3,3-trimethyl-2-methylideneindoline with two equivalents of different ortho-hydroxy-substituted aromatic aldehydes afforded novel photochemically bifunctional compounds. Molecules of these compounds include two functionally different fragments: the substituted azomethine (salicylideneimine or hydroxynaphthyl-methylideneimine) fragment in which intramolecular proton transfer can be induced by electronic excitation and the spiropyran fragment in which the O-C_spiro bond can dissociate upon UV-light absorption to form the merocyanine form. No conjugation between the azomethine and pyran fragments is observed in the initial state of the molecule. The compounds synthesized manifest the photochromic properties and luminescence.