Anion-coordination- and π-π-stacking-interaction-driven assembly of a complex Frank-Kasper structure

Abstract

Constructing artificial sophisticated architectures from simple small-molecular subunits by cooperative interactions remains one of the most formidable challenges. Herein, we report a complex supramolecular structure, {{[CoL(SCN)]₂₀}{[CoL(SCN)]₂₄}₃(SO₄)₂₃(HSO₄)₄₆}·246(CH₃CN) (1), that arises from the assembly of [CoL(SCN)]⁺ with SO₄²⁻ and HSO₄⁻ (L = tris(2-benzimidazolylmethyl)amine) under solvothermal condition. The crystallization of compound 1 is driven by the cooperation of the π-π stacking interactions between [CoL(SCN)]⁺ cations and the hydrogen bonds between [CoL(SCN)]⁺ and SO₄²⁻ and HSO₄⁻. [CoL(SCN)]⁺ cations self-associate through intermolecular π-π stacking interactions to create two π-stacked polyhedral 5¹²-{[CoL(SCN)]₂₀} dodecahedra and 5¹²6²-{[CoL(SCN)]₂₄} tetrakaidekahedra. These two π-stacked polyhedral subunits coexist in the same lattice in a 1:3 ratio and coordinate with SO₄²⁻ and HSO₄⁻, resulting in a complex Frank-Kasper (FK) A15 structure. This research demonstrates that small-molecular scaffolds can assemble into sophisticated architectures and creates exciting perspectives for constructing sophisticated clathrate structures from simple small molecules.