A significant consequence of the formation of a complex between
molecular hosts and guests is the fact that the physicochemical
properties of the partners can change upon association.
A host–guest complex usually consists of a smaller molecule contained
inside a larger concave species (e.g., a macrocycle); hence,
complexation is expected to cause remarkable changes in the environment
and properties of the guest. A particularly interesting case
is when the reactivity of the guest is affected upon inclusion into a
host. As the vast literature in the field demonstrates, complexation
can modify both the thermodynamics and the kinetics of processes
undergone by a molecular guest