From trigonal bipyramidal to platonic solids: Self-assembly and self-sorting study of terpyridine-based 3d architectures

Using a series of tritopic 2,2':6',2'-terpyridine (tpy) ligands constructed on adamantane, three discrete 3D metallo-supramolecular architectures were assembled, i.e., trigonal bipyramidal, tetrahedron, and cube. The self-assembly used tritopic ligands as corner directing units and metal ions as glue units at the edge. The angles of the linkers between adamantane and tpy head play a critical role in guiding the assembled structures, which have the general formula of M_3nL_2n, where M denotes metal ion and L denotes ligand. All complexes were fully characterized by ¹H, ¹³C NMR, diffusion-ordered NMR spectroscopy, ESI-MS, and traveling-wave ion mobility-mass spectrometry. The binary mixtures of LA and LC or LB and LC underwent a self-sorting process that led to the self-assembly of discrete 3D structures. The self-sorting behavior is solely based on the angles precoded within the arm of tritopic ligands. Moreover, kinetic study of preassembled cube and tetrahedron demonstrated a slow ligand exchange process toward a statistical mixture of hetero tetrahedrons with LA and LB.