Spiropyrans and spirooxazines 13. Synthesis and photochromic properties of benzoxazolyl-substituted spirobenzopyrans

Abstract

New benzoxazolyl-substituted spiroindoline-benzopyrans with electron-withdrawing groups in the indoline fragment were obtained. These compounds exhibit positive P- and T-type photochromism. Structural correlations of the spectrokinetic properties depending on the variation of substituents in the indoline part of the spiropyran molecules were established. Electronwithdrawing groups were found to cause a bathochromic shift of the long-wavelength absorption maxima of the merocyanine isomers as compared to the unsubstituted spiropyran and decrease their lifetime. Conversely, an introduction of electron-donating groups results in a hypso chromic shift of the absorption maxima and an increase in the lifetime of the colored isomers of spiropyrans. Electron-withdrawing substituents at the position 5 of the indoline fragment cause the increase of the colorability of the spiropyrans.