The asymmetric unit of the title compound, C9H11N3O2, contains two mol­ecules (A and B), which exist in Z conformations with respect to their C=N double bond. The dihedral angles between the benzene ring and the pendant hy­droxy­carbamimidoyl and acetamide groups are 28.58 (7) and 1.30 (5)°, respectively, in mol­ecule A and 25.04 (7) and 27.85 (9)°, respectively, in mol­ecule B. An intra­molecular N—H⋯N hydrogen bond generates an S(6) ring in both mol­ecules. Mol­ecule A also features an intra­molecular C—H⋯O inter­action, which closes an S(6) ring. In the crystal, the mol­ecules are linked by N—H⋯O, N—H⋯N, O—H⋯O, O—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds and C—H⋯π inter­actions, generating a three-dimensional network.

In the cation of the title compound, C9H12NO2 +·Cl−, the dihedral angle between the 2-oxoethanaminium N—C—C(=O)– plane [maximum deviation = 0.0148 (12) Å] and the benzene ring is 7.98 (8)°. The meth­oxy group is approximately in-plane with the benzene ring, with a C—O—C—C torsion angle of −2.91 (18)°. In the crystal, the cations and chloride anions are connected by N—H⋯Cl and C—H⋯Cl hydrogen bonds, forming a layer parallel to the bc plane. A C—H⋯π inter­action further links the layers.

The title mol­ecule, C15H14ClN, exists in a trans configuration with respect to the C=N bond [1.2813 (16) Å]. The dihedral angle between the benzene rings is 52.91 (6)°. The crystal structure is stabilized by weak inter­molecular C—H⋯π inter­actions.

The asymmetric unit of the title compound, C15H15NO, contains two independent mol­ecules, both of which exist in trans configurations with respect to the C=N bonds [1.278 (2) and 1.279 (2) Å]. In each mol­ecule, intra­molecular O—H⋯N hydrogen bonds generate S(6) ring motifs. In one mol­ecule, the benzene rings form a dihedral angle of 13.38 (9)°, while in the other mol­ecule the dihedral angle is 30.60 (10)°. In the crystal, the two independent mol­ecules are linked via weak inter­molecular C—H⋯O hydrogen bonds.

The title mol­ecule, C13H8Cl3NO, exists in a trans configuration with respect to the C=N bond [1.278 (2) Å]. The benzene rings form a dihedral angle of 24.64 (11)°. The mol­ecular structure is stabilized by an intra­molecular O—H⋯N hydrogen bond, which generates an S(6) ring motif. In the crystal, π–π stacking inter­actions [centroid–centroid distances = 3.6893 (14) Å] are observed.

In the title compound, C16H20N4, the 1H-imidazo[4,5-c]quinoline ring system is approximately planar, with a maximum deviation of 0.0719 (15) Å. An intra­molecular C—H⋯N hydrogen bond contributes to the stabilization of the mol­ecule, forming an S(6) ring motif. In the crystal, the mol­ecules are stacked along the b axis through weak aromatic π–π inter­actions between benzene and imidazole and benzene and pyridine rings [centroid–centroid distances = 3.6055 (10) and 3.5342 (10) Å, respectively].

In the title compound, C21H20ClN5·H2O, the 1H-imidazo[4,5-c]quinoline ring is approximately planar, with a maximum deviation of 0.0795 (7) Å, and it forms a dihedral angle of 7.65 (3)° with the chloro­phenyl ring. In the crystal, the components are linked into chains along the a axis via inter­molecular N—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds. One of the H atoms of the water mol­ecule is disordered over two positions with a site-occupancy ratio of 0.80 (4):0.20 (4).

In the title compound, C14H17N5, the 1H-imidazo[4,5-c]quinoline ring system is essentially planar, with a maximum deviation of 0.0325 (7) Å. In the crystal, a pair of inter­molecular N—H⋯N hydrogen bonds link neighbouring mol­ecules, forming an inversion dimer and generate an R 2 2(10) ring motif. These dimers are further connected into a chain along the b axis via inter­molecular C—H⋯N hydrogen bonds, resulting in an R 2 2(14) ring motif.