Photophysical characteristics of diphenyl carbazide-laser flash photolysis and fluorescence studies

The photophysical characteristics of diphenyl carbazide (DPC) have been investigated in various protic and aprotic polar solvents. Shifts in fluorescence spectra showed good linear fits with the ET(30) polarity scale and the solvent polarity function Δf. The emitter state is identified as having charge transfer character and is estimated to have a dipole moment of ∼8.6 D. Excited state lifetimes determined from transient absorption and fluorescence lifetime studies match well. Triplet–triplet absorption and phosphorescence emission (at 77 K) have been characterized and the triplet state energy is estimated to be ∼80 kcal/mol. Our experimental results show that DPC behaves more like a keto compound than a hydrazide derivative.