Click Chemistry: Mechanistic Insights into the Role of Amines Using Single-Molecule Spectroscopy

Single-molecule spectroscopy is used to gain insights into the click chemistry reaction photocatalyzed by copper. We show that CuxO@Nb2O5 catalysts can act as truly heterogeneous photocatalysts and that the amine plays an important role in the complexation between the alkyne and the copper active site on the catalyst surface. For complex reactions occurring in the subnanomolar range, preassociation can be essential and cocatalysts (such as amines here) may play an enabling role facilitating the reagents "reunion" and prolonging the time available for reaction. This provides a rational analysis of the amine role in heterogeneous photocatalytic click chemistry.