Hydrated and anhydrous molecular complexes of benzenepentacarboxylic acid and 4,4′-bipyridine

Supramolecular assemblies of benzenepentacarboxylic acid (BPC) and 4,4′-bipyridine (bpy) as hepta- and di-hydrates in a 2:1 and 1:1 ratios of the respective co-crystal formers, as well as an anhydrous complex of 1:2 ratio have been reported. The three supramolecular complexes [(BPC−)2(bpy2+)(H2O)7], 1a, [(BPC−)(bpy+)(bpy)], 1b and [(BPC2−)(bpy2+)(H2O)2], 1c, were obtained by carrying out co-crystallization experiments at varied conditions. 1a and 1b were obtained at ambient and hydrothermal conditions, respectively, while 1c also was obtained at hydrothermal conditions but only in the presence of Ni(NO3)2. All the molecular complexes were characterized by single-crystal X-ray diffraction method. Molecules in all the complexes are packed in the form of stacked layers with the realization of host–guest network in 1a and 1c along a crystallographic axis, wherein the host network is formed by BPC and water molecules through different types of hydrogen bonding patterns and bpy molecules remain as guests in the voids, while in 1b, a ladder type network is observed.