Topological transformations in metal-organic frameworks: a prospective design route?

Structural reconstructions in the solid-state can be treated as changes in the organization of the system of interatomic interactions that are naturally described by the transformations of the structure topology. We review different kinds of such transformations in coordination polymers and their important subclass, metal-organic frameworks. Several examples of both reconstructive and displacive transformations in coordination polymers under numerous external stimuli are considered and topologically interpreted. We use the underlying net concept and the 'supernet-subnet' formalism to distinguish these two kinds of transformations and to rigorously describe the reconstructive transformations. We introduce the concept of transformation pattern, which characterizes the part of the structure undergoing the transformation, and exemplifies the transformation patterns of different complexities. The role of the topological approach for the design of coordination polymers and metal-organic frameworks is also discussed.