Seven supramolecular adducts of 4-dimethylaminopyridine and carboxylic acids constructed by classical H-Bonds and some noncovalent interactions

Abstract

Abstract Cocrystallization of the commonly available pyridine derivative, 4-dimethylaminopyridine, with a series of carboxylic acids gave a total of seven anhydrous and hydrous multicomponent adducts (4-dimethylaminopyridine): (4-methoxybenzoic acid) [(HDMAP) · (mba) · (Hmba), mba = 4-methoxybenzoate] (1), (4-dimethylaminopyridine): (4-(aminosulphonyl)benzoic acid) [(HDMAP) · (aspba), aspba = 4-(aminosulphonyl)benzoate] (2), (4-dimethylaminopyridine): (3-methylsalicylic acid)2 [(HDMAP) · (msal) · (Hmsal), msal = 3-methylsalicylate] (3), (4-dimethylaminopyridine): (3,5,6-trichlorosalicylic acid) [(HDMAP+) · (tcsal−), tcsal− = 3,5,6-trichlorosalicylate] (4), (4-dimethylaminopyridine): (2-pyrazinecarboxylic acid): 4H2O [(HDMAP+) · (pyza−) · 4H2O, pyza− = 2-pyrazine carboxylate] (5), (4-dimethylaminopyridine): (2,2′-biphenyldicarboxylic acid) [(HDMAP+) · (Hbpda−), Hbpda = hydrogen 2,2′-biphenyldicarboxylate] (6) and (4-dimethylaminopyridine)2: (dibenzoyltartaric acid) [(HDMAP) · (Hdbta) · CH3OH · H2O, Hdbta = hydrogen dibenzoyltartarate] (7). The seven adducts have been characterized by XRD technique, IR and elemental analysis, and the melting points of all adducts were also reported. Their structural and supramolecular aspects are fully analyzed. The result reveals that all the investigated crystals are organic salts with only the aryl N in DMAP protonated and the crystal packing is interpreted in terms of the strong N–H⋯O, N–H⋯N, O–H⋯N and O–H⋯O H-bond from DMAP and the acidic groups. Further analysis of the crystal packing of the salts indicated that a different family of additional CH–N, CH–O/CH3–O, CH-π/CH3-π, CH3–CH, CH3–Cl, C-π, O-π, Cl–Cl and π-π associations contribute to the stabilization and expansion of the total high-dimensional (1D-3D) structures. For the delicate balance of the various weak nonbonding interactions these structures adopted homo or hetero supramolecular synthons or both.