Porous Organic Cages as Building Blocks for Framework Materials.

Confined nanospaces play a fundamental role in nature, inspiring synthetic analogues that emulate biological precision and efficiency. Among these, porous crystalline materials such as covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and molecular cage compounds have emerged as powerful platforms for catalysis, separation, and energy storage. Recent developments highlight the potential of porous organic cages (POCs) as modular building blocks for the construction of advanced materials. In this Minireview, their integration into extended frameworks, such as Cage-COFs and Cage-MOFs, is described, as they allow precise control over porosity and enhance chemical robustness. These hybrids merge the structural regularity of COFs with the discrete functionality of cages, enabling the design of lightweight, hierarchically organised materials. In addition, cage-containing polymers and supramolecular frameworks are discussed. Collectively, these developments position POCs as versatile synthons for next-generation porous materials, unlocking pathways toward functional, adaptive, and recyclable architectures.