Bifunctional Photocatalysts: Exploiting Proximity for Enhanced Reaction Performance.

The bifunctional approach has often been employed in catalysis to obtain more effective and enantioselective transformations. In the sub-area of photocatalysis, bifunctional systems have been designed (i) to introduce chirality in the system and thus gain stereocontrol, and (ii) to more effectively exploit the short-lived catalytic intermediates (e.g., photoexcited species and radicals). In some cases, instead of two distinct catalytic units, a single photoactive group displaying also other types of activity can be employed ("bivalent photocatalysts"). This review aims to cover the most recent examples in this field, establishing-when possible-a comparison with the corresponding dual catalytic systems.