Strategies for binding multiple guests in metal–organic cages

The binding of multiple guests by a single entity can lead to new modes of host–guest interactions and thus new applications in, for example, catalysis and sensing. With the aim of developing modular systems that can promote and adapt to allosteric binding events, this Review explores current strategies used to bind multiple guests in the central and peripheral environments of coordination cages. The structural and functional consequences of multi-guest binding are examined, highlighting the methods by which guest configurations involving more than one copy of the same guest, as well as multiple different guests, may be designed. We thus aim to provide new methodological insights and tools into the design of new capsules for multiple guest-specific binding events, towards the development of guest–guest chemistry within synthetic systems. Selective binding of multiple guests within cages could lead to new applications in catalysis and sensing. This Review discusses the design of synthetic cages with the aim of developing and controlling guest–guest chemistry.