Electronic nature of new styryl dye bases: Linear photophysical, photochemical, and transient absorption spectroscopy studies

The features of the electronic structures of a series of new styryl dye bases were investigated and characterized by their steady-state and time-resolved spectral properties, including femtosecond transient absorption spepctroscopy and DFT quantum chemical calculations. The steady-state absorption and fluorescence spectra, fluorescence quantum yield, and lifetimes in solvents of different polarity at room temperature revealed specific redistribution of the electronic density and rearrangements in molecular geometry after electronic excitation influenced by the dimethylamino end substituents. Fast relaxation processes in the electronic structures of new styryl dye bases and the nature of their time-resolved excited state absorption spectra were investigated with femtosecond temporal resolution, and the role of twisted intramolecular charge transfer (TICT) effects was shown. Quantum chemical calculations of the electronic structure of the new styryl dye bases were performed using non-empirical Time Dependent Density Functional Theory level, and were in good agreement with experimental data.