NMR characterization of allenyl-naphthol in the photochromic process of 3,3-diphenyl-[3H]-naphtho[2-1,b]pyran

Allenyl-naphthol was produced after UV irradiation followed by visible light irradiation of 3,3-diphenyl-[3H]-naphtho[2-1,b]pyran (CH). Elucidation of its structure was obtained by 1D and 2D NMR spectroscopy. Kinetic study showed that its thermal bleaching followed a monoexponential decay, leading to an increase of concentration of TC merocyanine.