Supramolecular helical architecture from the self-assemblies of 2-chloro-5-nitro-benzoic acid and organic bases

Assembly of 2-chloro-5-nitro-benzoic acid (CNB) and organic bases containing nitrogen atom, 8-hydroxyquinaldine (purum), 1,2-bis(4-pyridyl)ethane (BPE), and 2-aminobenzimidazole, resulted in novel adducts with helical architecture. We present here an unprecedented single-stranded helix (left-handed and right-handed helices) in adduct 1. The helices are formed via three kinds of hydrogen bonding, O5–H5⋯O1, C11–H11B⋯O3, and C14–H14⋯O1. But the two helices are linked by C9–H9⋯O4 and C11–H11B⋯O3 H-bonds. The interactions result in the cavity with dimensions of 8 × 10.5 Å, respectively. Interestingly, the different single-stranded helical structure in adduct 2 is generated via Cl1⋯O1 interactions, where BPE linking the two helices by C9–H9⋯O1 and O3–H3⋯N2 H-bonds. The ring motifs and novel helical structures observed in the crystal packing suggest for further scopes in exploiting different substituent chloro-nitro-benzoic acid in a predictive manner or capturing useful nanoscale entities for self-assembly.