Metalloporphyrin-based D-A type conjugated organic polymer nanotube for efficient photocatalytic degradation

A series of porphyrin-based D-A type conjugated organic polymer (COP) nanotubes MTAPP-BT (M= H2, Zn, Cu, Fe) were synthesized through acid-catalyzed Schiff base reaction between metalloporphyrins (MTAPP) and benzothiadiazole (BT) units. Among them, CuTAPP-BT shows superior photocatalytic activity and recyclability for bisphenol A (BPA) degradation. The transfer and separation of photo-induced carriers can be significantly improved through the metal-to-ligand charge transfer (MLCT) and electron push-pull effect between porphyrin units (electron donor, D) and benzothiadiazole moieties (acceptor, A). The nanotube structure exposed abundant active sites and improved the adsorption capacity for BPA through the pi-pi interaction and surface hydrogen bond. The possible mechanism of photocatalytic degradation for BPA over CuTAPP-BT was proposed based on molecular orbital (MO) theory. This investigation will provide a new insight about design and synthesis of novel D-A type COPs with enhanced photocatalytic activities.