Selective photocatalytic formation of sulfoxides by aerobic oxidation of sulfides over conjugated microporous polymers with thiazolo[5,4‑d]thiazole linkage

Developing selective formation of sulfoxides by aerobic oxidation of sulfides over highly efficient visible-light photocatalysts is an essential but challenging task. Herein, a conjugated microporous polymer (CMP) photocatalyst with the desired linkage thiazolo[5,4‑d]thiazole (TzTz) is presented to undertake this task. Remarkably, a catalyst-free solvothermal process afforded TzTz-CMP-3 from tetra(4-formylphenyl)-benzene and dithiooxamide. The photocatalytic activity of TzTz-CMP-3 is demonstrated with the blue light-powered selective formation of sulfoxides by aerobic oxidation of sulfides. A wide range of sulfoxides can be effectively formed by oxidation of sulfides with excellent product selectivities (up to 99 %) over the TzTz-CMP-3 photocatalyst. The more symmetric π-conjugated aromatic ring of TzTz-CMP-3 endows it with more favorable activity than the less symmetric ones. This work underscores the symmetry of building blocks for CMPs for selective photocatalytic formation of valuable organic molecules.