Combining Brønsted base and photocatalysis into conjugated microporous polymers: Visible light-induced oxidation of thiols into disulfides with oxygen

Abstract

Numerous applications in visible light photocatalysis have been found over conjugated microporous polymers (CMPs) whose function could be rationally designed at the molecular level. In this context, the oxidation of thiols into disulfides entails proton and electron transfer and thus requires both Brønsted base and photocatalysis, which could be both combined into CMPs. With carbazole as a Brønsted base and an electron donor, CMPs were constructed to implement the synergistic deprotonation and oxidation of thiols into disulfides in ethanol (C2H5OH). Gratifyingly, the bifunctional CMPs could activate molecular oxygen (O2) to superoxide anion (O2•–) and promote the blue light-induced selective oxidation of thiols into symmetrical disulfides with high efficiency in C2H5OH. More remarkably, the highly selective formation of unsymmetrical disulfides could also be achieved without adding a Brønsted base. This work highlights the feasibility of combining cooperative photocatalysis into CMPs for versatile chemical transformations.