Conjugated Dimeric and Trimeric Perylenediimide Oligomers

Dimeric and trimeric molecules comprising perylenediimide units conjugatively linked by phenylene, ethynylene, or a butadiynylene spacer via the bay positions were prepared. Electrochemical and photophysical characterizations showed that oligomers connected by C-C triple bond(s) exhibited effectively lowered LUMO compared to the monomer. Molecular modeling confirmed that the C-C triple bond realized efficient delocalization of frontier orbitals, while phenylene was less competent in extending the conjugation, partially due to steric interactions.