Photoswitchable Cu( ii )/Cu( i ) catalyses assisted by enzyme-like non-covalent interactions in Cu( ii )–melamine coordination polymers for installing CO 2 /CS 2 and CF 3 groups in heterocycles

Despite concerns over the environmental impact of isoelectronic CO 2 and CS 2 , they remain useful C1 building blocks with industrial utility, and trifluoromethylation could enhance the lipophilicity and metabolic stability of agrochemicals and pharmaceuticals. Merging the CO 2 /CS 2 moiety together with the CF 3 group in one heterocyclic scaffold is both environmentally and pharmaceutically valuable, but it is still challenging for the homogeneous Cu-catalytic protocols to circumvent the issue of residual heavy metals, and the aggregation and sulfur-poisoning effect of Cu-species. In this report, a highly durable Cu( ii )–melamine coordination polymer Cu–TDPAT, assembled from melamine-based ligand H 6 TDPAT and Cu( ii ) salt, was employed in the heterogeneous approach. The photoinduced electron transfer from the melamine-based ligand to the Cu( ii ) node of Cu–TDPAT and the ground-state back electron transfer enabled the controllable Cu( ii )/Cu( i ) switch. The enzyme-like non-covalent interactions not only enriched and activated CO 2 /CS 2 , the allylamine substrate, and Togni's reagent II, the CF 3 radical precursor, but also drew close distances between them to facilitate the reaction. These advantages benefit from synergising the ground-state Cu( ii )-triggered CO 2 installation and the photogenerated Cu( i )-catalysed trifluoromethylation steps within the construction of biointeresting heterocycles in a sustainable and recyclable manner. In particular, this heterogeneous approach was applicable to the construction of a central nervous system agent derivative when CS 2 was employed instead of CO 2 , showing the superior durability of Cu–TDPAT against sulfur-poisoning compared with its homogeneous counterpart.