Different supramolecular assemblies in two 1:1 proton-transfer compounds of sulfobenzoic acids with aromatic amines

Two 1:1 proton-transfer complexes of sulfobenzoic acids with aromatic amines, namely 4-[2-(4-pyridyl)ethenyl]pyridinium 2-carboxybenzenesulfonate, C(12)H(11)N(2)(+).C(7)H(5)O(5)S(-), (I), and 1,10-phenanthrolin-1-ium 4-carboxybenzenesulfonate dihydrate, C(12)H(9)N(2)(+).C(7)H(5)O(5)S(-).2H(2)O, (II), have very different hydrogen-bonding patterns compared with reported organic sulfobenzoic acid complexes. In (I), two cations and two anions form a four-molecule loop, in which pi-pi interactions occur. In (II), the anions and water molecules form a three-dimensional hydrogen-bonding network, while the cations only act as pendant components. The water molecules play a central role in the formation of the abundant hydrogen-bonding architecture in (II). The relative poorness and richness of hydrogen bonds in (I) and (II), respectively, give rise to novel hydrogen-bonding patterns.