Photoinduced hydrogen atom transfer in trans-1-(1′-hydroxy-2′-naphthyl)-3-(1-naphthyl)-2-propen-1-one

trans-1-(1′-Hydroxy-2′-naphthyl)-3-(1-naphthyl)-2-propen-1-one (trans-NHC) exhibited a fluorescence spectrum (λmax = 650 nm) with a large Stokes shift (10,500 cm-1) in benzene at room temperature, indicating that intramolecular hydrogen atom transfer took place in the singlet excited state. On laser flash photolysis, the T-T absorption spectrum (λmax = 660 nm) assigned to the tautomer and the ground state transient spectrum (λmax = 480 nm) assigned to the ground state trans-keto form were observed. The former spectrum indicates that adiabatic intramolecular hydrogen atom transfer also took place in the excited triplet state.