L-Histidinium p-toluene­sulfonate

In the title salt, C₆H₁₀N₃O₂⁺·C₇H₇O₃S⁻, the imidazole ring makes a dihedral angle of 70.93 (12)° with the plane of the toluene ring. In the crystal, the ions are linked via N—H...O and weak C—H...O hydrogen bonds forming two-dimensional networks lying parallel to (001). These networks are linked via C—H...π inter­actions, forming a three-dimensional structure.

Ethyl 2,5-di-tert-butyl-5-eth­oxy-4-oxo-4,5-di­hydro-1H-pyrrole-3-carboxyl­ate

The title compound, C₁₇H₂₉NO₄, contains a chiral center and crystallizes as a racemate. The asymmetric unit consists of two non-equivalent mol­ecules, in which the carbeth­oxy groups have markedly different orientations [C(=O)CC(OEt)=O torsion angles = 59.3 (2) and 156.0 (2)°]. In the crystal, mol­ecules form chains along [101] through N—H...O hydrogen bonds.

2-Amino-4-methyl­pyridinium 2-nitro­benzoate

In the title mol­ecular salt, C₆H₉N₂⁺·C₇H₄NO₄⁻, the original pyridine N atom of 2-amino-4-methyl­pyridine is protonated and the carb­oxylic acid group of nitro­benzoic acid is deprotonated. In the crystal, the ions are linked by N—H...O hydrogen bonds, forming chains propagating along [001]. The chains are linked via C—H...O hydrogen bonds, forming two-dimensional networks lying parallel to the bc plane.

4-Nitro­phenol–piperazine (2/1)

In the title adduct, C₆H₅NO₃·0.5C₄H₁₀N₂, the piperazine ring possesses inversion symmetry and has a chair conformation. Its mean plane makes a dihedral angle of 65.45 (7)° with the 4-nitro­phenol ring. In the crystal, the piperazine ring is linked to two 4-nitro­phenol mol­ecules via O—H...N hydrogen bonds. The mol­ecules are also linked via bifurcated N—H...(O,O) hydrogen bonds involving the NO₂ O atoms, forming a two-dimensional network lying parallel to (102). The networks are linked via C—H...O hydrogen bonds, forming a three-dimensional structure.