Influence of Configurational Isomerism of Pyridine π Bridge in Donor-π Bridge-Acceptor Type Covalent Triazine Frameworks on The Photocatalytic Performance

Covalent triazine frameworks (CTFs) involving a donor-pi bridge-acceptor (D-pi-A) structure are considered one of the most promising photocatalytic materials, in which the pi bridge is known to play an important role in influencing the photocatalytic performance. So far, much effort has been directed at the designing of the different pi bridge structure to facilitate the photo-induced charge separation. However, the orientation of the pi bridge units (configurational isomerism) has not been considered. In this paper, a pair of pyridine-bridged D-pi-A type CTFs, named TFA-P1-CTF and TFA-P2-CTF, were designed to investigate how the orientation of the pi bridge would influence their performance in the photocatalytic oxidation of olefins into carbonyl compounds. Interestingly, due to the superior charge separation capability, TFA-P2-CTF was found to be able to catalyze the reaction more efficiently than TFA-P1-CTF. Our study eventually provided a guide for the design of D-pi-A type CTFs as high-performance photocatalytic materials via tuning the configurational isomerism of the pi bridge unit for use in chemical transformations. A pair of configurational isomeric D-pi-A type CTFs involving pyridine pi bridge (named TFA-P1-CTF & TFA-P2-CTF, depending on the orientation of the pyridine unit) was synthesized, which interestingly demonstrated different performance as metal-free photocatalysts in the oxidation of olefins to carbonyl compounds under blue light irradiation. image