Phenothiazine-linked covalent triazine frameworks for enhanced photocatalytic aerobic oxidation reactions

The novel phenothiazine-linked covalent triazine framework (CTF, named as TPDH-PTBA), as well as the benzene- or triazine-linked counterparts (named as TPDH-TFPB and TPDH-TAPT, respectively), have been synthesized via direct polycondensation of terephthalimidamide and trisformyl precursors in DMF. Characterization of these three CTFs indicated the formation of macrocycle rings that were formed via covalently linked phenothiazine (or benzene) and triazine units. Among the CTFs, TPDH-PTBA with phenothiazine units exhibited a relatively broad band gap of ∼2.08 eV and excellent photocatalytic activity towards aerobic oxidation reactions. Specifically, the conversion rates of photocatalytic benzylamine coupling and anisothioether oxidation reactions by TPDH-PTBA were almost 100%, significantly higher than those of TPDH-TFPB and TPDH-TAPT. We proposed a photocatalytic pathway of these CTFs based on the experimental and theoretical evidences. Our findings highlight the potential of structural design at the molecular level to improve the intrinsic properties and photocatalytic performance of CTFs. These resulting porous organic polymers offer promise for green and sustainable application in organic synthesis and pollutant degradation.