Anion-Coordination-Driven Assembly of Chiral Quadruple and Single Helices Controlled by Countercations

Enantiopure helical assemblies were constructed by chiral C 2 -symmetric bis-bis(urea) ligands ( L S/R ) with phosphate or hydrogen phosphate anion, which is dictated by the countercation. In the presence of smaller cations (TMA + or TEA + ), the chiral ligands coordinate to dihydrated phosphate to form homochiral quadruple helicates (TMA) 6 [(PO 4 ·2H 2 O) 2 L S/R 4 ]. However, when larger cations (TPA + or TBA + ) were used, the ligand tends to assemble with monohydrated hydrogen phosphate ions into infinite single helices (TPA) 2 n [(HPO 4 ·H 2 O) L S/R ] n or (TBA) 2 n [(HPO 4 ·H 2 O) L S/R ] n . The predisposed point chirality next to the anion binding center in the ligands has a profound impact on the resulting assemblies, and their chirality is manipulated in a predictable manner.