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Hybrid materials, fabricated by the combination of inorganic and organic components, have potential applications in chemistry and are endowed with the advantages of both building elements. There are several types of intermolecular interactions present in these hybrid compounds, including electrostatic forces, π-π stacking and hydrogen-bonding interactions, the latter playing an important role in the construction of three-dimensional architectures and stabilizing supramolecular crystal structures. Analysis of the intermolecular interactions and their influence on packing modes therefore requires focused scientific attention. Four new organic-inorganic salts, namely 2-amino-4-methyl-3-nitropyridinium hydrogen sulfate, C6H8N3O2+·HSO4−, bis(2-amino-4-methyl-3-nitropyridinium) sulfate, 2C6H8N3O2+·SO42−, 2-amino-3-methylpyridinium hydrogen sulfate, C6H9N2+·HSO4−, and bis(2-amino-3-methylpyridinium) sulfate monohydrate, 2C6H9N2+·SO42−·H2O, have been synthesized and characterized by X-ray diffraction. The crystal structures are stabilized by intra- and intermolecular hydrogen bonds, as well as by weak π-π stacking and lp-π (lp is lone pair) interactions. Hirshfeld surface analysis was employed in order to study intermolecular interactions. [ABSTRACT FROM AUTHOR]

Tetrahydro-1-benzazepines have been described as potential antiparasitic drugs for the treatment of chagas disease and leishmaniasis, two of the most important so-called `forgotten tropical diseases' affecting South and Central America, caused by Trypanosoma cruzi and Leishmania chagasi parasites, respectively. Continuing our extensive work describing the structural characteristics of some related compounds with interesting biological properties, the crystallographic features of three epoxy-1-benzazepines, namely (2 SR,4 RS)-6,8-dimethyl-2-(naphthalen-1-yl)-2,3,4,5-tetrahydro-1 H-1,4-epoxy-1-benzazepine, (1), (2 SR,4 RS)-6,9-dimethyl-2-(naphthalen-1-yl)-2,3,4,5-tetrahydro-1 H-1,4-epoxy-1-benzazepine, (2), and (2 SR,4 RS)-8,9-dimethyl-2-(naphthalen-1-yl)-2,3,4,5-tetrahydro-1 H-1,4-epoxy-1-benzazepine, (3), all C22H21NO, and two 1-benzazepin-4-ols, namely 7-fluoro- cis-2-[( E)-styryl]-2,3,4,5-tetrahydro-1 H-1-benzazepin-4-ol, C18H18FNO, (4), and 7-fluoro- cis-2-[( E)-pent-1-enyl]-2,3,4,5-tetrahydro-1 H-1-benzazepin-4-ol, C15H20FNO, (5), are described. Some peculiarities in the crystallization behaviour were found, involving significant variations in the crystalline structures as a result of modest changes in the peripheral substituents in (1)-(3) and the occurrence of discrete disorder due to the molecular overlay of enantiomers with more than one conformation in (5). In particular, an interesting phase change on cooling was observed for compound (5), accompanied by an approximate fourfold increase of the unit-cell volume and a change of the Z′ value from 1 to 4. This transition is a consequence of the partial ordering of the pentenyl chains in half of the molecules breaking half of the symmetry axes observed in the room-temperature structure of (5). The structural assembly in all the title compounds is characterized by not only (N,O)-H...(O,N) hydrogen bonds, but also by unconventional C-H...O contacts, resulting in a wide diversity of packing. [ABSTRACT FROM AUTHOR]

It is well known that pyrimidin-4-one derivatives are able to adopt either the 1 H- or the 3 H-tautomeric form in (co)crystals, depending on the coformer. As part of ongoing research to investigate the preferred hydrogen-bonding patterns of active pharmaceutical ingredients and their model systems, 2-amino-6-chloropyrimidin-4-one and 2-amino-5-bromo-6-methylpyrimidin-4-one have been cocrystallized with several coformers and with each other. Since Cl and Br atoms both have versatile possibilities to interact with the coformers, such as via hydrogen or halogen bonds, their behaviour within the crystal packing was also of interest. The experiments yielded five crystal structures, namely 2-aminopyridin-1-ium 2-amino-6-chloro-4-oxo-4 H-pyrimidin-3-ide-2-amino-6-chloropyrimidin-4(3 H)-one (1/3), C5H7N2+·C4H3ClN3O−·3C4H4ClN3O, (I a), 2-aminopyridin-1-ium 2-amino-6-chloro-4-oxo-4 H-pyrimidin-3-ide-2-amino-6-chloropyrimidin-4(3 H)-one-2-aminopyridine (2/10/1), 2C5H7N2+·2C4H3ClN3O−·10C4H4ClN3O·C5H6N2, (I b), the solvent-free cocrystal 2-amino-5-bromo-6-methylpyrimidin-4(3 H)-one-2-amino-5-bromo-6-methylpyrimidin-4(1 H)-one (1/1), C5H6BrN3O·C5H6BrN3O, (II), the solvate 2-amino-5-bromo-6-methylpyrimidin-4(3 H)-one-2-amino-5-bromo-6-methylpyrimidin-4(1 H)-one- N-methylpyrrolidin-2-one (1/1/1), C5H6BrN3O·C5H6BrN3O·C5H9NO, (III), and the partial cocrystal 2-amino-5-bromo-6-methylpyrimidin-4(3 H)-one-2-amino-5-bromo-6-methylpyrimidin-4(1 H)-one-2-amino-6-chloropyrimidin-4(3 H)-one (0.635/1/0.365), C5H6BrN3O·C5H6BrN3O·C4H4ClN3O, (IV). All five structures show R22(8) hydrogen-bond-based patterns, either by synthon 2 or by synthon 3, which are related to the Watson-Crick base pairs. [ABSTRACT FROM AUTHOR]

Comment on article by in this special issue on halogen bonding. [ABSTRACT FROM AUTHOR]