Structure of five molecular salts assembled from noncovalent associations between organic acids, imidazole, benzimidazole, and 1-(2-(1H-benzimidazol-1-yl)ethyl)-1H-benzimidazole

Cocrystallization of the imidazole derivatives, L1-L3, with a series of organic acids gave a total of five molecular salts with the compositions: (imidazole): (DL-10-camphorsulfonic acid) [(HL1(+))center dot(cpsa(-)), cpsa(-) = DL-10-camphorsulfonate] (1), (imidazole): (3,5-dihydroxybenzoic acid) [(HL1(+))center dot(3,5-dba(-)), 3,5-dba(-) = 3,5-dihydroxybenzoate] (2), (imidazole): (isophthalic acid): H2O [(HL1)(+)center dot(Hmpa)(-)center dot H2O, Hmpa(-) = hydrogenisophthalate] (3), (benzimidazole): (butane-1,2,3,4-tetracarboxylic acid) [(HL2(+))center dot(H(3)bta (-)), H(3)bta(-) = trihydrogen butane-1,2,3,4-tetracarboxylate] (4), and (benzimidazole)2: 1(2-(1H-benzimidazol-1-yl)ethyl)-1H-benzimidazole: (5-nitrosalicylic acid)(2) [(L-2)(2)center dot(H2L3)(2+)-(5-nsa(-))(2), 5-nsa(-) = 5-nitrosalicylatel, (5). The five salts have been characterized by XRD technique, IR, and EA, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the five investigated crystals the ring N in the imidazole moieties are protonated when the organic acids are ionized, and the crystal packing is interpreted in terms of the strong N-H center dot center dot center dot O H-bond from the imidazole and the ionized acids. In addition to the N-H center dot center dot center dot O H-bond, the O-H center dot center dot center dot O H-bonds were also established at the salts 2-5, compound 1 has the additional N-H center dot center dot center dot S H-bonds. Further analysis of the crystal packing of the salts displayed that a different family of additional CH-O/CH2-O/CH3-O, CH-S, CH-pi, NH-pi, and pi-pi associations contribute to the stabilization and expansion of the total 3D framework structures. For the coexistence of the various weak interactions these structures had homo or hetero supramolecular synthons or both. Some classical supramolecular synthons, such as R-1(2)(4), R-2(2)(7), and R-2(2)(8) usually observed in crystals of organic acids with imidazole, were again shown to be involved in constructing most of these hydrogen bonding networks. (C) 2017 Elsevier B.V. All rights reserved.