Excited-state dynamics of naphthoylnaphthvalene: valence isomerization of the lowest excited singlet state and intermolecular hydrogen-atom abstraction of the lowest excited triplet state

Abstract By measurements of phosphorescence and transient absorption spectra as well as steady-state photolysis of the title compound (NNV), it is concluded as follows: (1) In benzene and ethanol, intersystem crossing from the lowest excited singlet ( 1 NNV ∗ ) to triplet ( 3 NNV ∗ ) states competes withvalence isomerization of 1 NNV ∗ yielding ground-state naphthoylnaphthalene (NN). (2) In ethanol, the NNV ketyl radical (generated by hydrogen-atom abstraction of 3 NNV ∗ from the solvent molecule) also undergoes rapid valence isomerization and recombination of two NN ketyl radicals thus formed yields 1,1,2,2-tetranaphthyl-1,2-ethanediol (naphthopinacol).