Spectral behavior and photophysical parameters of (2Z)-3-[4-(dimethylamino) phenyl]-2-(4-fluorophenyl) prop-2-ene-nitrile (DPF) in different media

A new fluorophore, (2Z)-3-[4-(dimethylamino) phenyl]-2-(4-fluorophenyl) prop-2-ene-nitrile (DPF), was synthesized by knoevenagel condensation of 4-(dimethylamino) benzaldehyde and 4-fluorobenzyl cyanide in ethanol using NaOH as base. The electronic absorption and emission characteristic of DPF were studied in different solvents. The X-ray crystallographic structure of DPF was also investigated. DPF exhibits a red-shift in its emission spectrum as solvent polarity increases, indicating a large change in the dipole moment of dye molecule upon excitation due to intramolecular charge transfer in excited DPF⁎. The fluorescence quantum yield depends strongly on the properties of the solvents, which was attributed to positive and negative solvatokinetic effects. A crystalline solid of DPF gives a strong yellow emission at about 532 nm; these phenomena are important for the application of DPF dye in organic photoemitting diode. The photochemical quantum yield of cis-trans isomerization of DPF was also determined in different solvents. The DPF dye displays solubilization in both cationic (CTAB) and anionic (SDS) micelle and may be used as a probe to determine the critical micelle concentration (CMC) of SDS and CTAB.