Metal-Organic Nanocapsules with Functionalized s-Heptazine Ligands

A metalloorganic capsule was synthesized where the ligand is a derivative of heptazine with three carboxylic groups that are coordinated to Cu^II cations, forming paddle-wheel motifs. Each nanocapsule is neutral, with 12 Cu^II centers and 8 ligands adopting a rhombicuboctahedron shape. It has almost 3 nm diameter, and the main intermolecular interactions in the solid are π··· π stacking between the C₆N₇ heptazine moieties. The nanocapsules can form monolayers deposited on graphite as observed by atomic force microscopy, which confirms their stability in solution.