A series of rigidified dyes with either dodecyloxy or piperidyl donors in combination with either malononitrile or barbiturate acceptors were synthesized. To analyze the influence of varying donor (piperidyl vs dodecyloxy), chromophore (mono-, bis- or tricyclic system) and acceptor moiety (methyl barbiturate vs malononitrile) to the ground state polarity, a combination of several methods was employed: UV/Vis absorption and emission, quantum chemical computations, 1H as well as 13C NMR and cyclic voltammetry measurements. Depending on acceptor and donor moieties, the ground state was shifted from a neutral form to the cyanine limit and further to a zwitterionic structure. By using strong piperidyl donor and barbiturate acceptor substituents, the ground state was close to the cyanine limit, which resulted in strong cyanine-like absorption properties having a dominant 0-0 transition. When combining a weak dodecyloxy donor with a malononitrile or barbiturate acceptor, the neutral resonance form significantly contributed to the ground state leading to weaker but broader absorption spectra featuring transitions to higher vibronic states.
