Crystal engineering of organic clay mimics from 3,5-pyrazoledicarboxylic acid and amines

The syntheses and crystal structures of sixteen compounds containing the monoanion of 3,5-pyrazoledicarboxylic acid (H(2)PzDCA) and ammonium-based counterions are reported. The cations contain short-chain alkyl, long-chain alkyl, phenyl, and chloro-, methoxy-, and amine-substituted aryl groups. Self-complementary HPzDCA intermolecular hydrogen bonds create nearly planar sheets, to which the cations connect through hydrogen bonds. Twelve of the structures exhibit virtually identical hydrogen-bonded layers, but the distance between layers varies from 9.33 to 14.10 A (+/-20 %), depending on the cation. The comparison of the sixteen structures leads to the identification of a building block (HPzDCA) that creates remarkably reproducible, lamellar structures despite substantial changes in the counterion.