Solvent Effects on the Fluorescence Quantum Yields and Lifetimes of 1- and 2-Acetyl- or Benzoylanthracenes

Abstract The fluorescence quantum yields and lifetimes of 1- and 2-acetyl- or benzoylanthracenes were measured in various degassed solvents at room temperature. The natural fluorescence lifetime was evaluated to be 30–40 ns, depending a little on the compounds, but little on the solvent. This strongly supports the recent finding that the lowest excited singlet state of the acylanthracenes is of a ππ* character. On the basis of triplet-yield measurements, it was also confirmed that the low fluorescence yield in nonpolar solvents is due to an efficient intersystem crossing to an upper triplet state.