Installation\nof Copper(I) and Silver(I) Sites into\nTREN-Based Porous Organic Cages via Postsynthetic Metalation

Porous organic cages (POCs) and metal–organic\npolyhedra\n(MOPs) function as zero-dimensional porous materials, able to mimic\nmany functions of insoluble framework materials while offering processability\nadvantages. A popular approach to access tailored metal-based motifs\nin extended network materials is postsynthetic metalation, which allows\nmetal installation to be decoupled from framework assembly. Surprisingly,\nthis approach has only sparingly been reported for molecular porous\nmaterials. In this report, we demonstrate postsynthetic metalation\nof tetrahedral [4 + 4] POCs assembled from tris(2-aminoethyl)amine\n(TREN) and 1,3,5-tris(4-formylphenyl)benzene. The trigonally symmetric\nTREN motif is a common chelator in coordination chemistry and, in\nthe POCs explored herein, readily binds copper(I) and silver(I) to\nform cationic cages bearing discrete mononuclear coordination fragments.\nMetalation retains cage porosity, allowing us to compare the sorption\nproperties of the parent organic and metalated cages. Interestingly,\nintroduction of copper(I) facilitates activated oxygen chemisorption,\ndemonstrating how targeted metalation can be exploited to tune the\nsorption characteristics of porous molecular materials.