Porous Crystalline Organic Cages Made by Design

Shape-persistent organic cages are an intriguing class of molecular porous materials. Through hierarchical molecular design, size and shape of the intrinsic molecular voids are controlled by dynamic covalent chemistry, while pore structure and topology are governed by noncovalent alignment in the solid state. However, the predictable and reliable crystallization of organic cages is still challenging since long-range superstructures are solely based on weak and rather unidirectional supramolecular interactions. In this tutorial review, we provide a general classification of porous solid-state materials and discuss specific design principles regarding the dynamic covalent reactions, the small-molecule building blocks and solid-state engineering. Furthermore, we introduce the most important analytical techniques for porous materials with a special focus on organic cages.