1-Benzyl-3,3,5′,6′-tetramethylspiro[indoline-2,2′-[2H]pyrano[3,2-b]-pyridinium] iodide, its hydrate, and a neutral precursor of the salts: synthesis, crystal structure, photochromic transformations in solutions and in crystals

Abstract

A new 1-benzyl-3,3,5′,6′-tetramethylspiro[indoline-2,2′-[2H]pyrano[3,2-b]pyridinium] iodide, photochromic in the crystal state, was obtained. X-ray diffraction analysis was used for determination of crystal structures of the salt, its hydrate, and a neutral precursor. It was found that a replacement of the substituent in the indoline fragment leads to a considerable change in the crystal structure of both the neutral spiropyran and the salts as compared to the analogs studied earlier. Effects of crystal structure on photochromic properties were studied.