Huarong Huang

Methyl 4-bromo-3-hy-droxy-benzoate.

In the title compound, C8H7BrO3, the methoxycarbonyl group is twisted at a dihedral angle of 8.06u2005(4)° with respect to the benzene ring. In the crystal, molecules are connected by O—H⋯O hydrogen bonds into helical chains running along the b axis.

(3E,5E)-3,5-Bis(4-hy­droxy-3,5-di­methoxy­benzyl­idene)oxan-4-one monohydrate

In the title compound, C(23)H(24)O(8)·H(2)O, the six-membered ring of the oxan-4-one (tetra-hydro-pyran-4-one) ring displays an envelope conformation with the heterocyclic O atom at the flap position. The dihedral angles between the terminal benzene rings is 37.23u2005(10)°. Classical intermolecular O-H⋯O and weak C-H⋯O hydrogen bonds are present in the crystal structure.

(3E,5E)-3,5-Bis(4-hy-droxy-benzyl-idene)oxan-4-one.

In the title compound, C19H16O4, there are two 4-hydroxybenzyl substituents on the oxan-4-one (tetrahydropyran-4-one) ring, which exhibits an envelope conformation. The dihedral angles between pyranone ring and the two benzene rings are 26.69u2005(9) and 36.01u2005(9)° while the benzene rings make a dihedral angle of 20.88u2005(10)°. In the crystal, molecules are linked by intermolecular O—H⋯O hydrogen bonds into a supramolecular three-dimensional twofold interpenetrating hydrogen-bonded network.

1,3-Bis[4-(meth­oxy­carbon­yl)benz­yl]benzimidazolium bromide monohydrate

In the title compound, C25H23N2O4 +·Br−·H2O, the dihedral angles between the benzimidazole ring system and the two benzene rings are 87.77u2005(11) and 63.05u2005(11)°; the dihedral angle between the two benzene rings is 66.25u2005(13)°. The crystal structure exhibits C—H⋯O and O—H⋯Br interactions; it is also stabilized by π–π stacking interactions, with a face-to-face separation of 3.456u2005Å between parallel benzimidazole ring systems.

1,4-Bis[4-(meth­oxy­carbon­yl)benz­yl]-1H-1,2,4-triazol-4-ium bromide

In the title salt, C20H20N3O4 +·Br−, the dihedral angle between the benzene rings is 8.69u2005(16)°, and those between the benzene rings and the triazole ring are 69.98u2005(18) and 72.17u2005(18)°. In the crystal, C—H⋯Br hydrogen bonds link the cations and anions into chains along the c axis.

5-Hydr­oxy-1-methyl-3,4-dihydro-2H-pyrrolium hydrogensulfate

The title compound, C5H10NO+·HSO4 −, has been synthesized by reaction of 1-methylpyrrolidin-2-one with H2SO4 in a 1:1 molar ratio. The substituted pyrrolium ring adopts an envelope conformation. The hydrogensulfate anions form infinite helical chains parallel to the a axis via strong O—H⋯O hydrogen bonds. The pyrrolium cations are pendant from the chains. These cations are the hydrogen donors in the strong O—H⋯O hydrogen bonds to the hydrogensulfates. In addition, there are weak C—H⋯O hydrogen bonds in the structure.

3-[(R)-3,3-Dichloro-2-hydroxy­prop­yl]-8-hydr­oxy-6-meth­oxy-1H-isochromen-1-one

The title compound, C13H12Cl2O5, is an isocoumarin compound which has been isolated from the ethyl acetate extract of the fermentation broth of actinomycete Streptomyces sp. (V4) from the South China Sea. There are intra- and intermolecular hydrogen bonds and halogen bonds [Cl⋯Cl = 3.434u2005(2)u2005Å; C—Cl⋯Cl = 121.6°]. The intermolecular O—H⋯O hydrogen bonds link molecules into chains along the b axis.