Metal-ion-determined geometrical configurations of metallo-cages with different emission properties.

The formation of metallo-cages is affected by a variety of factors such as the ligands, metals, and anions, among which the impact of metals with different binding capacities is particularly important, but has rarely been studied in three-dimensional metallo-cages. Herein, we report the design of truxene-centered terpyridine ligands and the self-assembly of a series of tetrameric metallo-cages. The utilization of metal ions with strong (Zn2+, Fe2+) or weak (Cd2+) binding strength afforded 3D metallo-cages with low symmetry or highly symmetric metallo-tetrahedra, respectively, possessing totally different geometrical configurations. In addition, their photophysical properties and host-guest chemical properties were investigated.