Photochromic response of nanoparticles of spiropyran–MnPS3 intercalate: A search for optically bistable nanocomponents

Air-stable hybrid organic-inorganic nanoparticles comprising photochromic spiropyran (SP) species intercalated in layered MnPS3 were prepared by a microemulsion procedure in cyclohexane, using Brij-97 (polyoxyethylene-oleyl ether) surfactant. The nanoparticles (10–20 nm in size) were precipitated, purified and redispersed in water or organic solvents. Thin films of the nanoparticles were casted from organic solutions in the presence of polymer (PVP). Both the dispersed Mn1−xPS3(SP)2x nanoparticles and the film reversibly display fast colouration and bleaching processes upon UV and visible irradiation, respectively. The thermal relaxation of the merocyanine form (in the dark) appears to be considerably hindered by intercalation.