Cation–Anion Arrangement Patterns in Self-Assembled Pd2L4 and Pd4L8 Coordination Cages

TLDR: This work showcases selected examples of self-assembled cages whose guest uptake or even overall structural integrity is reversibly switched by light or small molecules with potential application in stimuli responsive materials (e.g., for sequestration of pollutants or stabilization of reactive compounds) up to functional nanosystems and molecular machines.

Abstract: ConspectusCompounds featuring one-dimensional regular arrangements of stacked metal complexes and alternating [cation–anion]∞ sequences have raised considerable interest owing to their peculiar electronic and optical properties as well as guest inclusion capabilities. While traditional ways to realize these structural motifs rely on crystalline compounds, exclusively existing in the solid state, recent progress in the area of metal-mediated supramolecular self-assembly allows for the rational synthesis of structurally well-defined short stretches of stacked metal complexes and cation–anion arrangements. Therefore, metal cations, counteranions, and suitably designed organic bridges are allowed to self-assemble in solution. While the bridges can be designed as cross-linkers to yield extended two- or three-dimensional networks such as layered materials, metal–organic frameworks (MOFs), or porous coordination polymers (PCPs), they can also be tailored to lead to discrete nanoscopic objects. Supramolecular hel...