Steady-state and time-resolved fluorescence behavior of coumarin-153 in a hydrophobic ionic liquid and ionic liquid-toluene mixture

► Steady state and time-resolved fluorescence of coumarin 153 has been studied. ► Ionic liquid and its mixture with toluene have been used. ► Time-zero spectrum shows blue shift in presence of toluene. ► Rotation of C-153 becomes faster with addition of toluene.