Porphyrinoid-based molecular cages as photocatalytic nanoreactors for organic transformations.

Abstract

Molecular cages have emerged as powerful platforms for photocatalysis due to their ability to combine substrate confinement with efficient light harvesting. In particular, porphyrinoid-based cages provide confined microenvironments that mimic enzymatic active sites while enabling photoinduced energy- and electron-transfer processes. This review explores the design, synthesis, and photocatalytic applications of porphyrinoid-based metal-organic and covalent cages, highlighting their use in promoting organic transformations of encapsulated guest molecules. The discussed systems promote a variety of visible-light-driven transformations, including photooxidations, oxidative coupling reactions and fullerene functionalization. Confinement effects play a crucial role by enhancing substrate preorganization, increasing local concentrations, facilitating charge and energy transfer, and improving selectivity and catalytic efficiency. While most reported examples rely on the generation of singlet oxygen and other reactive oxygen species, recent studies demonstrate the potential of direct photoredox pathways involving single-electron transfer. These advances establish porphyrinoid cages as promising nanoreactors for sustainable and selective photocatalytic transformations.