Persistent radical cation sp2 carbon-covalent organic framework for photocatalytic oxidative organic transformations.

Persistent radical covalent organic frameworks (COFs) have exhibited great application potential in the fields of photocatalysis, magnetism, and biology. However, there is still a lack of a simple, green, and effective way to produce persistent radical COFs. Here, we synthesized two sp2 carbon-covalent organic frameworks (sp2C-COFs) with persistent triphenylamine radical cation (TPA+•), which can be generated by simple light irradiation since the effective donor–acceptor heterojunction is formed in ordered skeleton. The number of persistent TPA+• will increase with the intensity of light irradiation and the photogenerated electrons generated simultaneously can be consumed by O 2 to form reactive oxygen species, which can be then used to carry out the oxidative organic transformations under visible light. In addition, femtosecond-transient absorption spectra prove that the difference in the structure of the two radical cation sp2C-COFs will significantly influence the charge recombination rate, so that the materials show different catalytic efficiency. [Display omitted] • Two sp2 C-COFs with persistent radical cation are designed and synthesized. • The radical cation and ROS(O2–•) can be generated by simple light irradiation. • Two sp2 C-COFs display superior photocatalytic performance in organic transformation. • The relationship between structure and performance is explored by fs-TA spectra. [ABSTRACT FROM AUTHOR]