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.

Unveiling the potential of a covalent triazine framework based on [1]benzothieno[3,2-b][1]benzothiophene (DPhBTBT-CTF) as a metal-free heterogeneous photocatalyst

“…CTFs are a promising type of material which have a 1,3,5-triazine ring covalently bonded to organic units with remarkable photophysical properties 12,13 that make them useful to be applied in different photocatalytic reactions. 14 CTFs have been employed as photocatalysts in aerobic oxidation reactions (sulfides, [15][16][17] benzyl alcohols 18 ) and oxidative coupling of amines or dehalogenation reactions, 19 and also are effective for oxidative degradation (methylene blue, safranin T or rhodamine B). 20 However, in order to increase the versatility of these materials, it is necessary to introduce other photoactive groups into the framework.…”

Efficient Photocatalytic Selective Oxidation of Benzylamines over Cobalt Molecular Catalyst Covalently Bonded to Carboxyl Functionalized Carbon Nitride

“…Some semiconductor photocatalysts have great potential in the synthesis of imines, such as TiO 2 , [9] In 2 S 3 , [10] BiOX (X = Cl, I, Br), [11] g-C 3 N 4 , [12] triazine photocatalysts. [13,14] In order to ensure the selectivity of imine products through coupling oxidation synthesis, homogeneous molecular catalysts have attracted extensive attention due to their advantages such as high activity and selectivity, tunable structure, and fine control of the active site environment. However, the stability, recyclability, and scale-up of homogeneous molecular catalysts over time are limiting factors for their development.…”

“…Some semiconductor photocatalysts have great potential in the synthesis of imines, such as TiO 2 , [ 9 ] In 2 S 3 , [ 10 ] BiOX (X = Cl, I, Br), [ 11 ] g‐C 3 N 4 , [ 12 ] triazine photocatalysts. [ 13,14 ]…”