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Abstract

Porous organic cages (POC) are an emerging class of functional materials containing cavities large enough to host guest molecules. In recent years, the use of dynamic covalent bond formation has resulted in a vast array of cage compounds with different geometries and sizes. One such commonly used reaction is the imine condensation, which forms cage compounds in excellent yields but has a major disadvantage due its chemically labile nature. This thesis deals with the transformation of imine cages to chemically robust amide cages via the Pinnick oxidation. Historically, amide cages have been synthesized by simply coupling acid chlorides and amines, however, this method is ineffective in accessing larger cage molecules with complex geometries. Using the Pinnick oxidation, a triptycene-based [4+6] salicylbisamide cage was synthesized, which could not be generated via an irreversible amide bond forming reaction. The novel amide cage exhibited excellent chemical and thermal stability, as well as a specific surface area of SA (BET) = 370 m2/g. The versatility of this method to obtain amide cages was established by carrying out a ‘scope and limitation’ study by varying parameters such as electronic effects, solubility, hydrolytic stability of the imine cage, and steric effects. Moreover, it was possible to successfully apply the Pinnick oxidation on imine cages derived from aromatic amines as well as aliphatic amines. Furthermore, the enhanced chemical stability of the amide cages offered a unique opportunity to post-functionalize the cage compounds by well-known reactions such as bromination, nitration, Suzuki coupling, C-H activated borylation, etc. Consequently, functional amide cages could be obtained which have great potential in the encapsulation of small molecules as well as construction of hierarchical structures (such as COFs or polymers).