In the title compound, C₁₄H₁₄N₂O₂, the dihedral angle between the two benzene rings is 9.67 (10)°. Two intra­molecular O—HN and N—HN hydrogen bonds involving the hydr­oxy and amino groups generate S(6) and S(5) ring motifs, respectively. In the crystal structure, N—HO hydrogen bonds link neighboring mol­ecules. Mol­ecules are also stacked in a head-to-tail fashion along the c axis through π–π inter­actions [centroid–centroid separation of 3.7357 (12) Å] and are further linked by weak inter­molecular C—Hπ inter­actions, giving a zigzag arrangement along the b axis.

The title compound, C₂₂H₂₀N₂O₄·2CHCl₃, a new Schiff base compound, lies across a crystallographic inversion centre. An intra­molecular O—HN hydrogen bond generates a six-membered ring, producing an S(6) ring motif. Inter­molecular bifurcated C—HO hydrogen bonds involving the two O atoms of the Schiff base ligand and the H atom of the chloro­form solvent of crystallization, generate an R²₁(5) ring motif. The crystal structure is stabilized by inter­molecular C—Hπ and π–π inter­actions [centroid to centroid distance = 3.6158 (10) Å]. In the crystal structure, mol­ecules are stacked down the c axis.

In the title compound, C₂₂H₂₀N₂O₄, the central benzene ring forms dihedral angles of 33.58 (7) and 35.27 (7)° with the terminal benzene rings. The mol­ecular conformation is stabilized by two intra­molecular O—HN hydrogen bonds. In the crystal structure, the mol­ecules are linked by inter­molecular C—HO inter­actions to form sheets parallel to the bc plane. The sheets are then stacked along the a axis. In addition, the crystal structure is stabilized by weak C—Hπ inter­actions.

In the title compound, C₁₅H₁₄O₃, the dihedral angle between the two benzene rings is 23.33 (6)°. Mol­ecules are linked into a chain along the b axis by inter­molecular C—HO inter­actions.

The title compound, C₂₁H₂₀N₂O₂, a Schiff base ligand, contains two independent mol­ecules (A and B) in the asymmetric unit, with similar conformations. In mol­ecule A, the central benzene ring forms dihedral angles of 30.79 (13) and 23.56 (13)°, respectively, with the amino and benzyl benzene rings, while in mol­ecule B these angles are 32.30 (13) and 13.13 (12)°. The mol­ecular structure is stabilized by intra­molecular N—HN and C—HO hydrogen bonds. The crystal structure is stabilized by N—HN hydrogen bonds and N—Hπ and C—Hπ inter­actions.

In the title mol­ecule, C₂₁H₁₈N₂O₂, all bond lengths and angles are normal. Weak inter­molecular N—HN hydrogen bonds link the mol­ecules into chains along the c axis. The crystal packing is further stabilized by van der Waals forces.

In the main mol­ecule of the title compound, C₂₂H₂₀N₂O₄·1.13CH₄O, the dihedral angles between the benzimidazole plane and the two benzene rings are 80.53 (10) and 82.76 (10)°. The solvent mol­ecules are disordered between three positions, with refined occupancies of 0.506 (13), 0.373 (13) and 0.249 (5). The crystal structure is stabilized by inter­molecular O—HO, O—HN and C—HO hydrogen bonds. The crystal studied was a merohedral twin [BASF ratio of 0.917 (1)/0.083 (1)].

The asymmetric unit of the title compound, C₂₂H₂₀N₂O₄·H₂O, comprises a substituted benzimidazole molecule and a water mol­ecule of crystallization. The dihedral angles between the benzimidazole ring system and the two outer benzene rings are 16.54 (4) and 86.13 (4)°. The dihedral angle between the two hydr­oxy-substituted benzene rings is 82.20 (5)°. In the crystal structure, inter­molecular O—HO hydrogen bonds, involving the hydr­oxy groups and water mol­ecules, form R₄⁴(8) ring motifs, and link symmetry-related mol­ecules into extended chains along the c axis. The crystal structure is further stabilized by weak inter­molecular C—HO hydrogen bonds, weak C—Hπ and π–π stacking [centroid–centroid = 3.6495 (6)–3.7130 (6) Å] inter­actions. Intra­molecular O—HO and O—HN inter­actions are also present.

In the title mol­ecule, C₂₂H₁₉Cl₃O₅S, the meth­oxy group is slightly twisted from the plane of the attached benzene ring by a torsion angle of 18.96 (14)°. In the crystal structure, mol­ecules are linked by inter­molecular C—HO inter­actions and short ClO contacts of 3.0170 (8) Å.

In the crystal structure of the title compound, C₁₁H₁₆N₂O₃, mol­ecules are linked by one O—HN and two N—HO inter­molecular hydrogen bonds into a three-dimensional network, which incorporates R₂²(14) and R₂²(16) graph-set motifs.

The title compound, C₂₈H₃₃N₂S₂P, adopts the thione tautomeric form, as supported by the C—S distance [1.6744 (18) Å]. The Schiff base exhibits an E conformation about the C=N bond but a Z conformation about the C—N bond. The terminal chain is disordered over two sets of sites with an occupancy ratio of 0.732 (3):0.268 (3). In the crystal, pairs of N—N—H hydrogen bonds between the thione groups link neighbouring mol­ecules into centrosymmetric dimers.

The title compound, C₂₀H₂₄N₂O₆, was obtained as an unexpected product by the reaction of hydrazinium dithio­carbazate with 2,3,4-trimeth­oxy­benzaldehyde in refluxing ethanol. The mol­ecule lies on a center of inversion. The crystal packing is stabilized by weak inter­molecular C—HO inter­actions.

A method is described for the growth from aqueous solution of Li_{1 - x}H_xIO₃ single crystals. Unit-cell parameter, low-frequency resistivity and the temperature dependence of the α - β transition for several x values were determined. With an increase in x there is an increase in a₀ and a decrease in C₀ compared with the lattice constants of LiIO₃. The maximum increase in a₀ is 0.082 Å and the maximum decrease of C₀ is 0.219 Å.

The low-frequency dielectric behaviour, the piezoelectric constant g₃₃ and Raman and IR spectra of Li_{1 - x}H_xIO₃ have been measured. The amount of hydrogen, x, in the formula Li_{1 - x}H_xIO₃ varies from 0.0 to 0.35. The curves ε₃₃ = ε₃₃(f) and tan δ = tan δ(f) show anomalous behaviour with respect to frequency and composition. The piezoelectric constant (g₃₃) tends to a maximum at the composition x ≃ 0.04. A model of the low-frequency relaxation spectra and the high value of ε is discussed.

Three new potassium hydrogen polyiodate compounds [KH_n(IO₃)_{1 +n}] have been grown from aqueous solution. Their cell parameters, d values and space groups are reported.

There are two mol­ecules in the asymmetric unit of the title compound, C₁₈H₁₈N₂O₃. In each one, the benzimidazole ring system is essentially planar, with maximum deviations of 0.027 (1) and 0.032 (1)Å, and makes dihedral angles of 38.64 (6) and 41.48 (6)°, respectively, with the attached benzene rings. An intra­molecular C—HO hydrogen bond is observed in each mol­ecule. The two independent mol­ecules are connected into a dimer by two inter­molecular O—HN hydrogen bonds. In the crystal, mol­ecules form a two-dimensional layers parallel to (012) via weak inter­molecular C—HO hydrogen bonds. In addition, weak π-π stacking inter­actions are observed with centroid–centroid distances of 3.5244 (12) and 3.6189 (12) Å.

The asymmetric unit of title compound, C₁₁H₁₄N₂O₄, consists of two crystallographically independent mol­ecules (A and B). In each, intra­molecular N—HO hydrogen bonds generate S(6) ring motifs. The mean plane of the nitro group forms dihedral angles of 4.5 (3) and 0.5 (3)° with the benzene ring in mol­ecules A and B, respectively. In mol­ecule A, there is disorder of the butyl­amino group which corresponds to an approximate 180° rotation about the N—C(H) bond, forming two sites with refined occupancies of 0.722 (6) and 0.278 (6). Mol­ecule B is similarly disordered but in addition there is further rotational disorder about the C(H)—C(H₂) bond giving a ratio of occupancies for three components of 0.42:0.35:0.23. In the crystal structure, inter­molecular O—HO hydrogen bonds link mol­ecules into centrosymmetric dimers generating R₂²(8) ring motifs. The crystal structure is also stabilized by weak inter­molecular C—HO inter­actions.