Hydrogen-bonded network in the salt 4-methyl-1H-imidazol-3-ium picrate.

In the title molecular salt, C4H7N2 (+)·C6H2N3O7 (-), the phenolic proton of the starting picric acid has been transferred to the imidazole N atom. The nitro groups are twisted away from the benzene ring plane, making dihedral angles of 12.8 (2), 9.2 (4) and 29.3 (2)°. In the crystal, the component ions are linked into chains along [010] via N-H⋯O and bifurcated N-H⋯(O,O) hydrogen bonds. These chains are further linked by weak C-H⋯O hydrogen bonds into a three-dimensional network. The complex three-dimensional network can be topologically simplified into a 4-connected uninodal net with the point symbol {4.8(5)}.

Hydrogen bonding in the crystal structure of the molecular salt of pyrazole-pyrazolium picrate.

The asymmetric unit of the title organic salt [systematic name: 1H-pyrazol-2-ium 2,4,6-tri-nitro-phenolate-1H-pyrazole (1/1)], H(C3H4N2)2 (+)·C6H2N3O7 (-), consists of one picrate anion and one hydrogen-bonded dimer of a pyrazolium monocation. The H atom involved in the dimer N-H⋯N hydrogen bond is disordered over both symmetry-unique pyrazole mol-ecules with occupancies of 0.52 (5) and 0.48 (5). In the crystal, the component ions are linked into chains along [100] by two different bifurcated N-H⋯(O,O) hydrogen bonds. In addition, weak C-H⋯O hydrogen bonds link inversion-related chains, forming columns along [100].

Two three-dimensional networks in two polymorphs of biphenyl-4,4'-diaminium bis(3-carboxy-4-hydroxybenzenesulfonate) dihydrate.

Two polymorphs of biphenyl-4,4'-diaminium bis(3-carboxy-4-hydroxybenzenesulfonate) dihydrate, C(12)H(14)N(2)(2+)·2C(7)H(5)O(6)S(-)·2H(2)O, have been obtained and crystallographically characterized. Polymorph (I) crystallizes in the space group P2(1)/c with Z' = 2 and polymorph (II) in the space group P-1 with Z' = 0.5. The benzidinium cation in (II) is located on a crystallographic inversion centre. In both (I) and (II), the sulfonic acid H atoms are transferred to the benzidine N atoms, forming dihydrated 1:2 molecular adducts (base-acid). In the crystal packings of (I) and (II), the component ions are linked into three-dimensional networks by combinations of X-H...O (X = O, N and C) hydrogen bonds. In addition, π-π interactions are observed in (I) between inversion-related benzene rings [centroid-centroid distances = 3.632 (2) and 3.627 (2) Å]. In order to simplify the complex three-dimensional networks in (I) and (II), we also give their rationalized topological analyses.

A new polymorph of 1,4-bis(imidazol-1-ylmethyl)benzene dihydrate and its hydrogen-bonded fivefold interpenetrated CdSO(4) network.

Single crystals of a new polymorph of 1,4-bis(imidazol-1-ylmethyl)benzene dihydrate (bix x 2H(2)O), C(14)H(14)N(4) x 2H(2)O, have been obtained by the hydrothermal method. The asymmetric unit is composed of two independent half-bix molecules, one on an inversion center and one on a twofold axial site, and two water molecules. The disordered water molecules link into discrete tetrameric water units via two O-H...O hydrogen bonds, forming planar R(4)(4)(8) rings. These tetrameric water units and bix molecules are further linked by two O-H...N hydrogen bonds into a three-dimensional network in which an R(20)(20)(106) hydrogen-bonded ring is observed. These large rings lead to the formation of a fivefold interpenetrated network. If both the tetrameric water units and the bix molecules can be regarded as connected nodes, one single three-dimensional net can then be rationalized as a CdSO(4) network. This study indicates that topological methodology can be applied in some cases in order to understand the inherent characteristics of some hydrogen-bonded supramolecular assemblies.

A two-dimensional layer in N,N'-bis[2-(hydroxymethyl)benzyl]ethylenediamine and a three-dimensional network in N,N'-bis[2-(hydroxymethyl)benzyl]ethylenediammonium bis(perchlorate).

In both title compounds, C(18)H(24)N(2)O(2), (Ia), and C(18)H(26)N(2)O(2)(2+) x 2 ClO(4)(-), (II), respectively, the two aryl rings are strictly parallel, with an inversion centre lying at the mid-point of each central CH(2)-CH(2) bond. Molecules in (Ia) are linked into two-dimensional layers by N-H...O hydrogen bonds. The component ions in (II) are joined together by a combination of N/O/C-H...O hydrogen bonds and C-H...pi and anion...pi interactions, forming a three-dimensional network. A structural understanding of (Ia) and (II) may provide some useful information about how and why their metal-organic complexes display various biological activities and function in catalytic processes.