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.