The multifaceted roles of M_nL_2n cages in catalysis

Metal–organic cages are versatile supramolecular architectures, fulfilling various distinct roles in the mediation of catalysed chemical reactions. MnL2n cages have become increasingly synthetically accessible in recent years, and their modular nature allows for precise tailoring for specific applications. Sophisticated MnL2n cages have now been deliberately designed to fulfil several roles, providing unique reactivity that begins to emulate the highly complex nature of enzyme active sites. Here we highlight the different functions played by MnL2n cages in the context of catalysed synthetic reactions: (1) protection of catalysts or substrates, (2) activation or preorganization of guests and (3) concentration enhancement of reactants or catalysts in confined space. We conclude by discussing future directions for the field, such as the potential to increase complexity further by developing stimuli-responsive, flexible or reduced-symmetry cages, ultimately progressing artificial cage catalysis towards the levels of catalytic control provided by biological host–guest architectures.