Organic molecular cages

Organic molecular cages represent a unique class of porous materials characterized by their discrete molecular nature and well-defined internal cavities, formed through covalent bonds between precisely designed organic building blocks. These molecular structures contain organized frameworks surrounding a central cavity, where organic components are precisely arranged to create functional internal spaces. Unlike extended networks such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), these cage compounds exist as distinct molecular entities, offering advantages in solution processability and structural precision.

The field of organic molecular cages emerged in the early 2000s, pioneered by the work of Cram, Lehn, and Pedersen, whose foundational research on host-guest chemistry and molecular recognition earned them the 1987 Nobel Prize. The first discrete organic cages were reported by Tozawa and Cooper in 2009, introducing permanently porous organic cages with intrinsic cavities. Since then, the field has grown significantly, driven by advances in synthetic chemistry and characterization techniques. Early examples demonstrated basic molecular containment, but modern designs achieve sophisticated functions, including selective molecular recognition, catalysis, and stimuli-responsive behavior. The ability to control cavity size and chemical environment at the molecular level distinguishes these materials from traditional porous systems.