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.

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.

Bis(2-hy­droxy­eth­yl)ammonium picrate

The asymmetric unit of the title salt, C₄H₁₂NO₂⁺·C₆H₂N₃O₇⁻, contain two bis­(2-hy­droxy­eth­yl)ammonium cations and two picrate anions. An intra­molecular N—H...O hydrogen bond occurs in each cation. In the crystal, mol­ecules are linked via O—H...O and N—H...O hydrogen bonds, which generate two R₂¹(6), an R₂²(10) and an R₂²(13) graph-set ring motifs. There are also a number of C—H...O hydrogen bonds present. The sum of these inter­actions leads to the formation a three-dimensional structure.