Tuning the Photocatalytic Activity through Linkages of Porous Conjugated Polymers Based on Triazines for a Selective Oxidation Reaction

Abstract

Conjugated polymers like conjugated microporous polymers (CMPs) and covalent organic frameworks (COFs) are burgeoning metal‐free photocatalysts for selective oxidation reactions. They possess outstanding features and salient advantages that are inextricably linked to structures at the molecular level. More effort should be devoted to seeking appropriate linkages which can define their crystallinity as well as photocatalytic activity. Herein, with thiazolo[5,4‐d]thiazole (TzTz) and imine as linkages, TzTz‐TA and TTI‐COF are prepared with triazine as the core, respectively. Conclusively, TTI‐COF shows high crystallinity, whereas TzTz‐TA is amorphous, belonging to CMP. However, TzTz‐TA exhibits better photocatalytic activities than TTI‐COF for the blue light‐driven selective aerobic oxidation of amines. The superior photoelectric properties and a more suitable reduction potential are imposed by the TzTz linkages to override the shortcoming of lack of crystallinity for TzTz‐TA. High selectivities for imines by photocatalytic oxidation of benzyl amines are achieved over TzTz‐TA. In addition, TzTz‐TA emerges with remarkable recoverability and recyclable stability. This study implies that tuning the linkages is essential for boosting the photocatalytic activity of porous materials.

Keywords

• conjugated polymers
• linkages
• photocatalyses
• selective oxidation
• triazines