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

Abstract

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.

Packing incentives and a reliable N–H⋯N–pyridine synthon in co-crystallization of bipyridines with two agrochemical actives

“…In 35 practice, however, packing in crystals is influenced by an intricate combination of close packing incentives, hydrogen bonding and other interactions and therefore there is as yet no reliable way to design co-crystals. Previously, we have been investigating the polymorphism and 40 versatile solvate formation of two agrochemical actives, thiophanate-methyl (TM) 10 and thiophanate-ethyl (TE) 11 (Scheme 1), and decided now to examine co-crystallization with common co-crystal formers, namely 4,4'-bipyridine (44bp) [12][13][14][15][16][17] and 2,2'-bipyridine (22bp) 18 (Scheme 1) as pyridine solvates of TM and 45 TE are also known. Due to the success with the first bipyridines, crystallizations with the similar 1,2-bis(4-pyridyl)ethane (44bpe) (Scheme 1) were also attempted.…”

Vibrational spectra, crystal structure, DFT quantum chemical calculations and conformation of the hydrazo – bond in 6-methyl-3-nitro-2-(2-phenylhydrazinyl)pyridine

“…The energetic positions of the vibrational modes corresponding to these fragments have been well established by other authors [39,40]. Therefore, in the present paper we focus on vibrational characteristics of the hydrazo and nitro groups, which can participate in the HB formation.…”

“…On this basis and the results obtained here the following descrip- 363-350, 206 cm À1 . The characteristic vibration of the pyridine ring, the ring breathing (ring pulsation), was assigned to the two bands at 992 and 1031 cm À1 in the Raman spectrum [40]. The highest intensity of these bands was in the Raman spectrum.…”

Crystal engineering rescues a solution organic synthesis in a cocrystallization that confirms the configuration of a molecular ladder

“…Whereas crystallization of the ladderane alone afforded an amorphous solid, cocrystallization with 3,5-dinitrobenzoic acid (3,5-DNBA) (ratio: 1∶4) in 1∶3 (v∕v) methanol∶nitromethane readily afforded colorless single crystals upon slow evaporation over 1 d (30,31). A 1 H NMR spectrum demonstrated both the ladderane and 3,5-DNBA to be present in a 1∶4 ratio in the solid whereas an infrared spectrum ruled out possible salt formation, with the acid groups (C ¼ O solid: 1;703 cm −1 ) being present in the neutral form (C ¼ O neutral: 1;708 cm −1 ) (30, 31).…”