Synthesis of Photochromic Heterocyclic-Fused Naphthopyrans. Tuning the Color and Fading Speed

Abstract

Abstract New photochromic 3-thienyl-3H-naphtho[1,2-b]pyrans fused to lactone and indole rings were efficiently prepared using a one-pot acid-catalyzed reaction, at room temperature, as the key step. These colorless photoswitches acquire intense red/brown shades under UV light and return spontaneously to the colorless state in the dark. The combination of the 3 heterocyclic rings assures a broad and intense absorption in the visible region and it allows a full switch between the two states in less than 1 min, at room temperature.