We have elucidated the relationship between the fluorescence quantum yield (Φ) of 4- monosubstituted benzofurazan (2, 1, 3-benzoxadiazole) compounds and the substituent group at the 4-position using a group of eleven such compounds. The absorption and fluorescence spectra of these compounds were measured in fifteen different solvents. Semi- empirical PM3 calculations were carried out to obtain the optimized geometry, energies, ...
