Achiral Benzoic Acid Derivatives as Chiral Cocrystal Building Blocks in Supramolecular Chemistry:  Adducts with Organic Amines

Achiral benzoic acid derivatives were cocrystallized with a range of amines, affording binary or ternary cocrystals [(p-nitrobenzoic acid)·(2-aminopyridine)] (1), [(p-nitrobenzoic acid)·(4,4‘-bipyridine)] (2), [(p-nitrobenzoic acid)·(p-methoxyaniline)] (3), [(3,5-dinitrobenzoic acid)·(2,2‘-bipyridine)] (4), [(3,5-dinitrobenzoic acid)·(4, 4‘-bipyridine)] (5), and [(phthalic acid)·(2-aminobenzimidazole)] (6) under specified conditions. All the prepared cocrystals have a common structural feature of the 2₁ screw axis. It is noteworthy that the cocrystals 1*, 4*, and 6*, achiral benzoic acid derivatives and nitrogen bases, are noncentrosymmetric and chiral cocrystals. Strong N−H···O interactions are involved in the chiral cocrystals, undoubtedly following the best donor/acceptor guidelines. X-ray single-crystal diffraction studies reveal that the stronger N−H···O and O−H···N interactions, as well as weaker C−H···O ones, are all among the driving forces for the construction of the hydrogen-bonding networks in 1−6. Thus, a two-dimensional (2D) framework is constructed for 2, and a three-dimensional (3D) column framework is constructed for 3 by multiple hydrogen bonds. There are pairwise interwoven sheets in 4 and 6. For 5, a V-shaped arrangement of molecules exhibits a parallel orientation.