Carbon-to-nitrogen atom transmutations in a covalent organic framework transform the visible light-triggered selective oxidation of sulfides

Abstract

The construction of covalent organic frameworks (COFs) for visible light-triggered chemical conversions has recently received substantial attention. In this work, four carbon-to-nitrogen atom transmutations in an established COF, TpBD-COF, lead to the design of a new COF, TpBmd-COF, transforming the photocatalytic activity for an arduous reaction. The integrations of 2,4,6-triformylphloroglucinol (Tp) with [1,1′-biphenyl]-4,4′-diamine (BD) and [5,5′-bipyrimidine]-2,2′-diamine (Bmd) afford TpBD-COF and TpBmd-COF, respectively. Both COFs have similar crystallinity, specific surface areas, and porous structures. However, TpBmd-COF exhibits much better separation and transport of photogenerated charge carriers than TpBD-COF. As such, TpBD-COF is inactive for blue light-triggered selective oxidation of organic sulfides with dioxygen, while TpBmd-COF delivers significant yields of organic sulfoxides. Overall, atom transmutations in a COF are a viable strategy for transforming photocatalytic activities.