Photochromic bi-naphthopyrans

Multiphotochromic molecular systems

“…Derivatives of 56 where the two NP are covalently linked have been obtained. 157 In these compounds, a thermally reversible photochromism is observed, by the appearance of a new band in the visible region between 450 and 550 nm, depending on the R substituents (see Fig. 14).…”

“…Concerning NP derivatives, an important synthetic effort has been directed towards obtaining NP dyads with various linkers and substitution patterns. [153][154][155][156][157][158][159][160][161] Compounds 54, 160 55, 161 56, 157 57, 154 and 58 159 are representative of this family, with different bridges, though additional homologous dimers can also be found. 155,156,158 The photochromic properties of the NP dyad 54, 160 where the two units are connected to a central phenyl ring at the meta position, were compared to those of the same compound with a para orientation.…”

Naphthopyran molecular switches and their emergent mechanochemical reactivity

“…235 Bis-naphthopyrans contain two naphthopyran subunits joined by a conjugated linker and are among the few classes of photochromic compounds capable of accessing distinctly colored states based on the duration or intensity of light exposure. 116,119,120,234,[236][237][238][239] Encouraged by the photochromic properties of the bisnaphthopyran photoswitches originally reported by Zhao and Carreira, 116,119,234 we designed a series of poly(methyl acrylate) polymers incorporating a bis-naphthopyran unit near the chain center for direct comparison of the photochemical and mechanochemical reactivity (Fig. 12a).…”