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

Abstract

[EN] 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 photo-oxidative 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.