Design of Supramolecular Layers via Self-Assembly of Imidazole and Carboxylic Acids

The supramolecular chemistry and crystal structures of salts of imidazole with one monocarboxylic acid ( 1 ), nine different dicarboxylic acids ( 2 − 10 ), and one tetracarboxylic acid ( 11 ) are reported. Salts 2 − 11 serve as building blocks that self-assemble via ionic O−H···O and N−H···O hydrogen bonds when crystallized. These strong hydrogen bonds generate two types of chains that intersect at the anions and form polar hydrogen-bonded layers with four different motifs. These layers serve as scaffolds with which to control molecular packing in two dimensions for engineering the structures of crystals. All imidazolium cations function as multidentate proton donors by forming two or three C−H···O hydrogen bonds in addition to two N−H···O hydrogen bonds. Strong O−H···O and N−H···O hydrogen bonds define structure and connectivity within layers, while weaker C−H···O hydrogen bonds dominate interactions between layers in these salts.