Crystal structures of eight 3D molecular adducts derived from bis-imidazole, bis(benzimidazole), and organic acids

The result reveals that among the eight investigated crystals both the end ring N in the bis(imidazole) moieties are protonated when the organic acids are deprotonated except 2, and 5, and the crystal packing is interpreted in terms of the strong ionic NH⋯O H-bond between the imidazolium and the deprotonated acidic groups. Except the NH⋯O H-bond, the OH⋯O H-bonds were also found at the salts 3, 4, 5, and 7, salt 5 has the additional NH⋯N H-bond, the NH⋯S H-bond was established at 8. Further analysis of the crystal packing of the adducts indicated that a different set of additional CHO/CH2O, CHCl, CH-π/CH2-π, ClC, ClN, OO, O-π, OH-π, and π-π associations contribute to the stabilization and expansion of the total 3D frameworks. For the coexistence of the various weak interactions these structures had homo or hetero supramolecular synthons or both. Some supramolecular synthons, such as R12(4), R22(7), and R22(8) usually found in crystals of organic acids with imidazole unit, were again shown to be appeared in constructing most of these H-bond networks.