Synthesis and fluorescence properties of carbazole and fluorene-based compounds

Three donor-acceptor (D-A) conjugated compounds consisted of carbazole and fluorene (Scheme 1) were synthesized via Wittig-Horner, Ullmann or Sonogashira reaction. Their photoluminescence properties were investigated in solution and solid state, respectively. Luminescence in various solvents revealed the intramolecular charge transfer (ICT) process exists in these D-A molecules. Correlation between the Stokes' shifts and solvent polarity parameters indicated that moderate large dipole moments exist in the excited states.