Spiropyrans: molecules in motion

5′-Substituted Indoline Spiropyrans: Synthesis and Applications

“…However, the electronic structure of the MCs derivatives was found to be extremely sensitive to influence of substituents in both indoline and pyran rings in these photochromes. By varying the acceptor or donor properties, steric hidrances and positions of the substituents, it is possible to polarize the π-system of the MC form sufficiently to reach a zwitterionic-like structure and observe negative solvatochromism in the push-pull-type dyes, containing electron-donating groups in the indoline and electron-withdrawing ones in the pyran moieties [4,5,10,14,23,26,27,[54][55][56].…”

“…Spiropyrans of the indoline series are in focus as the most promising and the most studied representatives of multi-sensitive spirocyclic compounds, which can be switched by a number of external stimuli, including light, temperature, pH, presence of metal ions, mechanical stress, and other compounds. The spectral properties and parameters of their phototransformations strongly depend on the substituents present in the molecule; therefore, a directed change in their nature enables the search for new photochromes with desired properties and various stimulus-responsive structural elements [4,5,17,[21][22][23][24][25][26][27][28].…”

Photo- and halochromism of spiropyran-based main-chain polymers

“…Main-chain SP-based polymers possess – just as their well-explored side chain equivalents – photo and pH- responsiveness, yet offer additional exclusive qualities, such as mechanochromism 11 and potentially larger motion change 29,30 upon the ring-opening of SPs. Synthetically, however, just a limited number of methods, e.g.…”

“…Main-chain SP-based polymers possessjust as their wellexplored side chain equivalentsphoto and pH-responsiveness, yet offer additional exclusive qualities, such as mechanochromism 11 and potentially larger motion change 29,30 upon the ring-opening of SPs. Synthetically, however, just a limited number of methods, e.g., Ring-Opening (Metathesis) Polymerization (ROP 26 /ROMP 31 ) or Suzuki polycondensation, 32 were employed to install SP moieties into the polymer backbone.…”