Structure-Property Relationships in Donor-Acceptor Systems With Thiophene/Furan π-Bridges Built by Iterative Oxidation-Decarboxylative Coupling.

This study investigates six donor-π-acceptor (D-π-A) compounds incorporating various π-conjugated bridges based on bifuran, bithiophene, terfuran, terthiophene, and mixed furan-thiophene sequences. These bridges were synthesized via a key decarboxylative coupling approach utilizing thiophene- or furan-based carboxylic acid derivatives and their corresponding bromo- or carbaldehyde analogs. This synthetic route enabled efficient coupling and reoxidation, facilitating the introduction of up to three consecutive heterocyclic units without a significant loss in yield. A comparative analysis of their optoelectronic properties demonstrates that both the nature and the sequence of the heterocyclic units within the π-conjugated bridge play a decisive role in governing the electronic structure and overall performance of the resulting materials.