Donor-Acceptor Pyridine-Based Conjugated Microporous Polymers for Visible-Light-Driven Reactive Oxygen Species...

Conjugated microporous polymers (CMPs) are attractive organic photocatalysts because their porosity, extended π conjugation, and tunable donor-acceptor (D-A) architectures can promote light harvesting, charge separation, and substrate transport. Herein we report two pyridine-based donor-acceptor CMPs, BTPP-TPA and BTPP-TPT, synthesized through Suzuki coupling of a tetrabrominated pyridine-containing building block (BTPP) with triphenylamine (TPA)- or triphenyltriazine (TPT)-based boronate monomers. Both CMPs exhibit high thermal stability, permanent porosity, broad visible-light absorption, and favorable electronic structures for photocatalytic applications. Notably, the more planar and nitrogen-rich BTPP-TPT framework shows enhanced interfacial charge transport, stronger dye-framework interactions, and superior photocatalytic activity relative to BTPP-TPA. BTPP-TPT delivered adsorption efficiencies of 98.29% for rhodamine B (RhB) and 98.24% for methylene blue (MB) within 90 min and achieved visible-light-driven photodegradation rate constants of 2.6 × 10^-2 min^-1 for RhB and 1.7 × 10^-2 min^-1 for MB. Spectroscopic and electrochemical studies, together with molecular orbital calculations, indicate that D-A polarization and linker planarity govern charge separation and reactive oxygen species generation in these frameworks. This work highlights how molecular-level engineering of pyridine-based CMPs can regulate porosity, electronic structure, and photocatalytic function, providing an effective strategy for metal-free polymer photocatalysts for wastewater remediation.