Mono- and di-substituted pyrene-based donor-π-acceptor systems with phenyl and thienyl π-conjugating bridges

The synthesis of a series of four donor-π-acceptor (D-π-A) compounds involving pyrene derivatized with hexylcyanoacetate acceptor groups connected by phenyl or thienyl π-conjugating spacers is described. The electronic properties are characterized by UV–Vis absorption spectroscopy, cyclic voltammetry theoretical calculations and solvatochromism experiments. The results indicate that the thienyl connectors leads to D-π-A systems with smaller optical gaps and stronger internal charge transfers attributed to the combined effects of the lower resonance energy of thiophene, the smaller twist angles between the pyrene block and the π-connector and the deformability of the thiophene ring.