Selective photocatalytic oxidation of sulfides with dioxygen over carbazole–fluorene conjugated microporous polymers

One sustainable concept emerges to implement the selective oxidation of sulfides with dioxygen (O2) at ambient conditions and has received increasing attention. As such, three donor–acceptor (D–A) type conjugated microporous polymers (CMPs) were connected via robust C C bonds prepared from FeCl3-promoted polymerization of monomers of 3,6-di(9H-carbazol-9-yl)-9H-fluorene with the 9H position of the fluorene moiety occupied by 1,1′-biphenyl-, difluoro-, or keto- group, furnishing 9,9′-(9,9′-spirobi[fluorene]-2,7-diyl)-bis-9H-carbazole-CMP (SFC-CMP), 9,9′-(9,9-difluoro-9H-fluorene-2,7-diyl)bis(9H-carbazole)-CMP (FFC-CMP), and 2,7-di(carbazol-9-yl)-fluoren-9-one-CMP (OFC-CMP), respectively. These three carbazole–fluorene CMPs could implement blue light-driven highly selective oxidation of sulfides into sulfoxides with O2 in methanol (CH3OH). Intriguingly, the SFC-CMP imparted the best photocatalytic activity for selective oxidation of sulfides in a broad scope. Besides, the SFC-CMP photocatalyst could be fully recovered even outperforming the fresh one. This work highlights that the properties of CMPs could be regulated by the D–A units like carbazole–fluorene to execute selective chemical transformations ambiently.