Metallo-Supramolecular Hexagonal Wreath with Four Switchable States Based on a pH-Responsive Tridentate Ligand.

In biological systems, many biomacromolecules (, heme proteins) are capable of switching their states reversibly in response to external stimuli, endowing these natural architectures with a high level of diversity and functionality. Although tremendous efforts have been made to advance the complexity of artificial supramolecules, it remains a challenge to construct metallo-supramolecular systems that can carry out reversible interconversion among multiple states. Here, a pH-responsive tridentate ligand, 2,6-di(1-imidazole-2-yl)pyridine (HDAP), is incorporated into the multitopic building block for precise construction of giant metallo-supramolecular hexagonal wreaths with three metal ions, , Fe(II), Co(II), and Ni(II), through coordination-driven self-assembly.

A Stable 3-4 Heterometallic Cluster with Magneto-Optical Activity.

A stable 3-4 heterometallic cluster, namely, {DyNiL(NO)(CO)(CHOH)}·CHCN (DyNi, HL = 8-hydroxyquinoline), has been solvothermally synthesized and structurally characterized. The compound exhibits an interesting structure in which a tetrahedron based on 4 ions interpenetrates with a square pyramid based on 3 ions. Besides, a unique intermolecular interaction was found in DyNi, giving rise to its high stability not only when it is in the solid state but also when it dissolves in organic solvents.