Covalent Post‐Synthetic Modification of Metal‐Organic Cages: Concepts and Recent Progress

Abstract

Metal‐organic cages (MOCs) are supramolecular coordination complexes that have internal cavities for hosting guest molecules and exhibiting various properties. However, the functions of MOCs are limited by the choice of the building blocks. Post‐synthetic modification (PSM) is a technique that can introduce new functional groups and replace existing ones on the MOCs without changing their geometry. Among many PSM methods, covalent PSM is a promising approach to modify MOCs with tailored structures and functions. Covalent PSM can be applied to either the internal cavity or the external surface of the MOCs, depending on the functionality expected to be customized. However, there are still some challenges and limitations in the field of covalent PSM of MOCs, such as the balance between the stability of MOCs and the harshness of organic reactions involved in covalent PSMs. This concept article introduces the organic reaction types involved in covalent PSM of MOCs, their new applications after modification, and summarizes and provides an outlook of this research field.

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“…Functionality enhancement: Integrating organic cages into COFs increases functionality, effectively modifying intrinsic properties for applications such as adsorption, sensing, catalysis, and beyond …”

“…This strategy facilitates the incorporation of dynamic and responsive components, paving the way for stimuli-sensitive materials Functionality enhancement: Integrating organic cages into COFs increases functionality, effectively modifying intrinsic properties for applications such as adsorption, sensing, catalysis, and beyond Hierarchical cavities: Organic cages offer hierarchical organization within COFs, featuring stable voids with apertures designed for external access, enriching the structural complexity and functionality of the material …”

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“…Moving beyond extended frameworks, the application of reticular chemistry principles to the rational design and synthesis of discrete structures, such as metal–organic cages − and porous organic cages, − represents a burgeoning frontier. These discrete entities offer distinctive advantages, such as meticulous control over shape and size, extensive opportunities for functional modification, and inherent solution processability, positioning them as key components for a variety of applications from catalysis , and gas separation − to drug delivery , and sensing. − Despite the clear potential, a systematic exploration of discrete structures through the lens of reticular chemistry remains sparse .…”