Molecular geometries were optimized at the B3LYP/6-31+G* level of theory. Characterization of the excited states was performed with linear response TDHF/STO-3G and CIS/STO-3G calculations using the GAUSSIAN quantum chemistry program (Development Version i14+). The STO-3G basis set is chosen for the sake of convenience during analysis of the composition of the excited states and electron dynamics. The main conclusions of this study are not expected to be affected by this choice.