A series of five symmetrical and four unsymmetrical diaryl substituted diketo-pyrrolo-pyrroles was synthesized; two unsymmetrical derivatives are reported for the first time. The relationship between the theoretical excitation energies of the S0→ S1 transition, computed by time dependent density functional theory and the experimental positions of 0–0 vibronic bands in the visible absorption (or fluorescence excitation) spectra was studied. ...
