Postsynthetic Modification of Calixarene-Based Porous Coordination Cages

Porous coordination cages have garnered considerable interest as a distinct class of permanently porous materials due to their unique molecular nature, setting them apart from more traditional metal-organic materials, including metal-organic frameworks. Postsynthetic modification (PSM) of cages offers a promising avenue for tailoring their properties, but challenges remain, including maintaining solubility, functional group compatibility and stability, and potential changes in porosity. Here, we explore novel approaches to address these challenges and enhance the versatility of coordination cages. We initially targeted alkylation and acylation reactions, where anhydrides were ultimately employed as relatively mild reagents. To expand the toolkit of PSM reactions, we explored Pd-catalyzed cross-coupling reactions, where high-throughput methodologies were used to optimize reaction conditions. In this regard, we identify Pd(OAc)(2) with a 1,1 '-bis(di-tert-butylphosphino)ferrocene ligand as an efficient reagent for the PSM of aryl-bromide functionalized cages with arylboronic acids. Overall, this work broadens the scope of the PSM of cages and highlights its potential as an avenue to tailor cages for specific applications in gas adsorption, separation, and catalysis.