Electronic excitations in a ladder type fluoranthenopyracylene in its neutral and charged states: A theoretical and experimental study

This work reports on theoretical and spectroelectrochemical studies of a thermally and chemically stable fluoranthenopyracylene ladder type molecule 7,10,17,20 tetra-p-dodecylphenyl(bisfluorantheno[8,9-a,c]) pyracylene. Optimal geometries were evaluated for neutral and positively/negatively charged states performing density functional theory (DFT) calculations. Absorption spectral line frequencies as well as oscillator strengths were calculated using the time-dependent DFT and collective electronic oscillator (CEO) methods. The calculated optical spectra are in good agreement with the experimental measurements in solution. The difference of charged states produced by reduction and/or oxidation versus the electronic neutral forms on the vertical excitation energies and CEO electronic density matrix distribution has been characterized and compared to the geometrical changes of the molecular fragments. The localization of excitation in the optical transition of the charged states shows that the excitation is less separated and shows larger electronic coherence in comparison to the neutral form.