Low and High Molecular Mass Dithienopyrrole–Naphthalene Bisimide Donor–Acceptor Compounds: Synthesis, Electrochemical and Spectroelectrochemical Behaviour

Two low molecular weight electroactive donor–acceptor–donor (DAD)‐type molecules are reported, namely naphthalene bisimide (NBI) symmetrically core‐functionalized with dithienopyrrole ( NBI‐(DTP) 2 ) and an asymmetric core‐functionalized naphthalene bisimide with dithienopyrrole (DTP) substituent on one side and 2‐ethylhexylamine on the other side ( NBI‐DTP‐NHEtHex ). Both compounds are characterized by low optical bandgaps (1.52 and 1.65 eV, respectively). NBI‐(DTP) 2 undergoes oxidative electropolymerization giving the electroactive polymer of ambipolar character. Its two‐step reversible reduction and oxidation is corroborated by complementary EPR and UV/Vis–NIR spectroelectrochemical investigations. The polymer turned out to be electrochemically active not only in aprotic solvents but also in aqueous electrolytes, showing a distinct photocathodic current attributed to proton reduction. Additionally, poly(NBI‐(DTP) 2 ) was successfully tested as a photodiode material.