Regioselective photodimerization as a tool for light-regulated catalyst assembly.

While photoisomerization has dominated the design of photoswitchable catalysts, this work introduces an alternative approach: leveraging light-induced photodimerization to assemble catalytically active species. The adopted strategy is based on a acrylamidylpyrene derivative equipped with a TACN·Zn(ii) catalytic unit. This system undergoes a visible-light-induced [2 + 2] cycloaddition, which is both regioselective and reversible, to form a catalytically active photodimer. While the -to- photoisomerization of the monomer has no significant effect on catalysis, the photodimerization leads to a six-fold enhancement in catalytic activity. The photodimer's catalytic efficiency is attributed to the clustering of catalytic units, facilitating a more efficient transphosphorylation reaction. Notably, this system demonstrates the ability to temporally control catalytic reactivity, as the active dimer can be reverted to the monomers upon irradiation with UV light. This work highlights the potential of photodimerization as a robust alternative strategy for regulating catalytic activity and opens new avenues for light-responsive catalysis with temporal control.