Reversibly photoswitchable catalysts for the aldol reaction based on azobenzene-bearing organocatalysts

Development of smart artificial switchable catalysis has aroused much research interest in wide fields. Herein, a series of azobenzene-bearing organocatalysts with L/D-proline units (Ⅰ-Ⅴ) were developed and evaluated in the catalytic efficiency for aldol reaction. The photoisomerization behavior of the azobenzene-bearing organocatalysts and the effect of light as external stimulus on the catalytic performance were investigated in depth. Worth to mention that the reaction rate of the aldol reaction can be regulated by light irradiation, detailly, the azobenzene-bearing organocatalysts displayed a substantial difference in photoswitchable “ON-OFF” catalytic activity, which exhibited great potential for dynamic control in smart catalytic systems.