Fluorescence of dicyanovinyl julolidine in a room-temperature ionic liquid

Steady-state and time-resolved emission of 9-dicyanovinyl julolidine (DCVJ) in 1-butyl 3-methyl imidazolium tetrafluoroborate ([bmim][BF4]) were studied. The emission spectrum of DCVJ, obtained after properly subtracting the fluorescence of the solvent, peaks at similar wavelength as in acetonitrile, and its total intensity decreases with temperature, as it does in normal liquids. However, the activation energy of the radiationless process is much lower than that of [bmim][BF4] viscosity, which points to a free volume controlled deactivation for DCVJ excited state.