Red-shifted luminescence from naphthalene-containing ligands due to pi-stacking in self-assembled coordination cages.

Incorporation of ligands containing substituted naphthalene cores into coordination cages results in extensive aromatic pi-stacking between ligands; this results in a red-shifted 'excimer-like' luminescence component from the naphthyl groups compared to the free ligands, which is diagnostic of, and can be used to monitor, cage assembly.