Construction and interconversion of anion-coordination-based (‘aniono’) grids and double helicates modulated by counter-cations

Abstract

Supramolecular assembly of well-defined discrete architectures has been of great interest due to the tunable properties of these structures in functional materials and bio-mimicking. While metal-coordination-driven assembly has been extensively studied, anion-coordination-driven assembly (ACDA) is just emerging for constructing complex supramolecular structures. Herein two A_2<i>n</i> <b>L</b> _2<i>n</i> (A = anion, <b>L</b> = ligand; <i>n</i> = 1 or 2) 'aniono'-supramolecular assemblies, <i>i.e.</i> double helicates and the first anion grid, have been constructed based on the coordination between phosphate (PO₄ ^3-) anion and a bis-tris(urea) ligand. Moreover, the aniono-grid and double helicate motifs can be readily interconverted under ambient conditions by simply changing the counter-cation. These results redefine the power and scope of ACDA, which may represent a new approach in the assembly of well-defined architectures in parallel with the metal coordination-driven assembly of metallo-supramolecules.