Tailoring the structure and photocatalytic properties of [1]benzothieno[3,2-b][1]benzothiophene (BTBT)-based porous organic polymers

• BTBT-based porous organic polymers were synthesized via Friedel–Crafts, and Sonogashira–Hagihara reactions. • BTBT-CTF, featuring direct BTBT-triazine linkages, shows high activity in benzyl alcohols oxidation to aldehydes. • BTBT-CTF enables photooxidative synthesis of benzimidazoles from benzyl alcohols. • BTBT-CTF was applied for the synthesis of the pharmaceutically relevant 2-(4-fluorophenyl)-1H-benzo[d]imidazole. • BTBT-CTF demonstrated reusability over sixt consecutive catalytic cycles. The organic semiconductor [1]benzothieno[3,2-b][1]benzothiophene (BTBT) has been incorporated into porous organic polymers to create heterogeneous photocatalysts with tunable structural and electronic properties. In this study, four BTBT-based polymeric networks, BTBT-HCP, BTBT-CTF, BTBT-CMP, and BTBT-PAF were synthesized using different strategies, including Friedel–Crafts reactions and palladium-catalyzed cross-coupling methods. The resulting materials exhibited distinct thermal and optical properties, with the latter showing a strong correlation with their catalytic performance. All four photocatalysts were evaluated in the photooxidation of aromatic alcohols. Among them, BTBT-CTF, which has direct bonds between the BTBT and triazine units, demonstrated the highest efficiency and was further employed in a one-pot, two-step reaction for the photooxidative synthesis of benzimidazoles. This process combined the initial photooxidation of aromatic alcohols with a subsequent condensation with o-phenylenediamine without isolating the intermediate aldehyde. These results highlight the potential of BTBT-based materials for sustainable photooxidations and light-driven heterocyclic synthesis.