10.1039/c0cc02986f
The study presents the synthesis and characterization of novel, highly colored benzopentalenonaphthalenones derived from the intramolecular capture of a merocyanine moiety from diarylmethanol-substituted 2H-naphtho[1,2-b]pyrans under acidic conditions. These compounds exhibit interesting photochromic properties, changing color upon irradiation with ultraviolet light and reverting to colorless upon cessation of irradiation. The researchers also observed that the coloration was influenced by the electronic and steric properties of the substituents. Further, they explored the cascade process that leads to the formation of these compounds, involving initial intramolecular trapping of a cation and subsequent cyclization, tautomerization, and oxidation steps. The study provides insights into the design of new functional dyes with potential applications in areas such as dye-sensitized solar cells, photodynamic therapy, and sensor systems.