Negative Photochromism of Solutions of Functionalized Spiropyrans in a Water—Acetonitrile Mixture

A spectral-kinetic study of photochromic functionalized nitro-substituted indoline spiropyrans in water-acetonitrile mixtures has allowed to observe for the first time the effect of negative photochromism due to the self-assembly of photochromic molecules in a mixed solvent with the formation of hydrogen bonds and proton complexes.