Conformational Control of a Metallo-Supramolecular Cage via the Dissymmetrical Modulation of Ligands.

In nature as well as life systems, the presence of asymmetrical and dissymmetrical structures with specific functions is extremely common. However, the construction of metallo-supramolecular assemblies based on dissymmetrical ligands still remains a considerable challenge for avoiding the generation of unexpected isomers with similar thermodynamic stabilities, especially for three-dimensional supramolecular structures. In this study, a strategy for the conformational control of metallo-supramolecular cages via the enhancement of ligand dissymmetry was proposed. Four dissymmetrical ditopic ligands were designed and synthesized. By increasing the dissymmetry of length or angle, conformations of assemblies were precisely controlled to form discrete cis-Pdn L2n molecular cages.