Chapter 4: Stabilising Reactive Intermediates in Cages

Discrete, three-dimensional metal–organic cages with well defined internal void spaces have been shown to promote the formation and increase the lifetime of reactive intermediates. The size and shape match between a host molecule and its guest, in addition to complementary electrostatic interactions between the host and guest, have been identified as the key factors governing stability of the encapsulated high-energy species. Herein we review examples of cage molecules that effectively shield encapsulated guests, altering their behaviour from that observed in bulk solution, and also explore the role of host molecules in stabilising high-energy intermediates that can be used productively in chemical transformations.