Three-Motif Molecular Junction-Conjugated Microporous Polymers for Enhanced Photocatalytic Organic Transformations

Conjugated microporous polymers (CMPs) provide a versatile platform for incorporating various photoactive structures into porous frameworks through the strategic design of molecular building units. This molecular engineering approach allows for precise modulation of bandgap structures and electronic configurations at the atomic level. Current research predominantly focuses on two-motif molecular designs for CMP-based photocatalysts, whereas three-motif architectures remain significantly underexplored with respect to synthetic accessibility, structure–property relationships, and the mechanistic elucidation of photocatalytic processes. Herein, we report the synthesis of a thiazolo[5,4-d]thiazole (TZ)-incorporated three-motif molecular junction CMP (CMP-TZ-BTDT) through condensation polymerization of dithiooxamide with 4,4′,4″,4‴-((benzo[c][1,2,5]thiadiazole-4,7-diylbis(1,4-phenylene))bis(azanetriyl))tetrabenzaldehyde (BTDT). Strategic incorporation of benzothiadiazole as a photoactive component within the CMPs framework significantly enhances visible-light absorption capacity, resulting in improved photocatalytic performance through the efficient generation and separation of photogenerated charge carriers. Systematic characterization reveals that CMP-TZ-BTDT with a three-motif molecular junction architecture, as a heterogeneous photocatalyst, has a broad substrate scope and recyclability, enabling diverse visible-light-mediated organic transformation reactions. This molecular engineering approach provides significant insights into the rational design of advanced photocatalytic CMP systems with customized optoelectronic properties.