Supramolecular building blocks from modular self-assembly of biimidazolium species. Crystal structure of 2-(2-1H-imidazolyl)-1H-imidazolium chloride monohydrate

Abstract

A supramolecular building block II is recognized from the crystal structure of compound [(H₃biim)⁺(Cl⁻)]·H₂O (H₂biim = 2,2′-biimidazol) (1), in which a Cl⁻ is linked to a (H₃biim)⁺ cation via symmetrical N–H⋯Cl⁻ hydrogen bonds, as the remaining N–H groups of the (H₃biim)⁺ connect with another [(H₃biim)⁺(Cl⁻)] fragment to form the final dimeric unit II. The self-assembly of II through C–H⋯Cl⁻ hydrogen bonds leads to an extended 2D-array with cavities. The stacking of these layers allows the formation of channels containing water molecules. The modular building blocks III and IV, observed in the previously reported crystal structures of [(H₃biim)⁺(I⁻)·(H₂biim)] (2a) and [(H₄biim)²⁺(Cl⁻)₂] (3b), show the same sort of hydrogen-bonded 2D-network as that found in 1, but with a dramatic change in the dimensions of the cavities.