Facile Self-Assembly of Metallo-Supramolecular Ring-in-Ring and Spiderweb Structures Using Multivalent Terpyridine Ligands

A series of metallo-supramolecular ring-in-ring structures was generated by assembling Cd-II ions and the multivalent terpyridine ligands (L1-3) composed of one 60 degrees-bent and two 120 degrees-bent bis(terpyridine)s with varying alkyl linker lengths. The mechanistic study for the self-assembly process excluded an entropically templated pathway and showed that the intramolecularly complexed species is the key intermediate leading to ring-in-ring formation. The next-generation superstructure, a spiderweb, was produced in quantitative yield using the elongated decakis(terpyridine) ligand (L-5).