Because sunlight is the most abundant energy source on
earth, it
has huge potential for practical applications ranging from sustainable
energy supply to light driven chemistry. From a chemical perspective,
excited states generated by light make thermodynamically uphill reactions
possible, which forms the basis for energy storage into fuels. In
addition, with light, open-shell species can be generated which open
up new reaction pathways in organic synthesis. Crucial are photosensitizers,
which absorb light and transfer energy to substrates by various mechanisms,
processes that highly depend on the distance between the molecules
involved. Supramolecular coordination cages are well studied and synthetically
accessible reaction vessels with single cavities for guest binding,
ensuring close proximity of different components. Due to high modularity
of their size, shape, and the nature of metal centers and ligands,
cages are ideal platforms to exploit preorganization in photocatalysis.
Herein we focus on the application of supramolecular cages for photocatalysis
in artificial photosynthesis and in organic photo(redox) catalysis.
Finally, a brief overview of immobilization strategies for supramolecular
cages provides tools for implementing cages into devices. This review
provides inspiration for future design of photocatalytic supramolecular
host–guest systems and their application in producing solar
fuels and complex organic molecules.